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How To: Combat Phentermine Side Effects

General Phentermine Questions?
Check out the ultimate guide to phentermine weight loss pills!

Although phentermine will suppress your appetite and boost your energy levels, making it easier to eat healthy and exercise more, it can also produce negative side effects. While you’re on your weight loss journey, it can be difficult enough to focus on your goals without having the extra problems of symptoms, such as insomnia, a dry mouth and dizziness. However, many of these phentermine side effects often pass after a few days or weeks, and, in the meantime, we have some tips for you on how to relieve these side effects while still focusing on working towards your weight loss goals.

1. Dry Mouth

This is probably the number one phentermine side effect, and while it may not sound too uncomfortable, those who have experienced it will probably tell you a different story. Often it is an uncomfortable sensation with an almost insatiable thirst, and can even lead to mouth ulcers and sore gums. The best way to combat this is to drink a lot of water with Phen Drink added to improve taste and really get your mouth back to normal. Always keep a bottle with you and take regular sips from it to keep yourself hydrated, aiming for a daily total of 64 oz, which is around 8 glasses. You should also cut down on coffee and alcohol consumption, as both are diuretics and can leave your mouth feeling even drier.

As well as drinking plenty of water, you should eat more fruit and vegetables with a high water content, such as cucumber, celery, watermelon, and grapefruit. Snacking on these will help stimulate your saliva glands and add moisture to your mouth while also keeping hunger at bay. Our taste buds can also become inhibited by a dry mouth, so a great way to combat both is to sprinkle cayenne pepper on your food; this spice acts as nature’s wake-up call, helping to stimulate your salivary glands, tantalize your taste buds and boost your metabolism!

2. Insomnia

Phentermine is a stimulant, and for this reason it can cause those who take it to have insomnia. Getting a good night’s sleep is crucial for maintaining a healthy body and mind, and when you’re trying to lose weight, a lack of sleep can also have adverse effects on your best efforts to slim down. Lack of sleep makes you more susceptible to stress and depletes your energy levels, both of which cause us to crave unhealthy foods and make bad food choices.

If you’re having trouble sleeping, it’s a great idea to wind down before going to bed. A warm bath can really help to relax you, as can a soothing massage on the pressure points of your neck and back. Create a relaxing atmosphere with some calming music and drink a glass of warm milk or a cup of herbal tea, such as chamomile, to help you de-stress. Steer clear of caffeine as much as possible, especially later in the day. You should remove stressors from your bedroom and avoid working or watching TV in there, plus make sure that your bedroom and your bed are comfortable and at the right temperature for you – a lumpy mattress, cold feet or heavy, hot blankets can inhibit sleep and are easily fixed.

3. Constipation

If you feel constipated while taking phentermine, you should increase your water intake as it’s the best liquid for washing away waste and toxins in the body. Other drinks such as juice and soda can’t compare, as their high sugar levels can actually make constipation worse. You should avoid fats and refined sugar, and although caffeine can be considered a quick fix for constipation, it is also a diuretic, meaning that it takes moisture out of stools, making them harder to pass – for this reason you should stay away from coffee, cola and alcohol. If you’re also experiencing bloating as a result of constipation, you should avoid sodium and artificial sweeteners.

You should aim to increase your fiber intake by eating high-fiber foods such as whole grain bread and cereal, beans, fruit, and vegetables. Prunes are especially good, as they contain sorbitol, a stool-loosening sugar that naturally helps relieve constipation. Exercise is another way to promote healthy bowel movements, and while moderate to rigorous physical exercise is preferred, just going for a quick walk around the block will help.

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4. Dizziness

To combat the phentermine side effects of dizziness, make sure you’re drinking lots of water, as dizziness is often caused by dehydration. For this reason, you should also avoid caffeine and cut back on salt, as both can cause you to become more dehydrated.

Dizziness can be as a result of a lack of food, so make sure you’re eating enough – remember that 1,200 calories is the minimum anyone should go to while dieting, but if you’re heavier to start with, male or very tall, you should probably be eating more than this. An imbalance in your blood sugar levels can also cause you to feel light-headed, so try eating five small meals throughout the day to keep these levels steady, your appetite satisfied and your metabolism running smoothly. More specifically, your diet may be lacking in iron so try to include iron-rich food, such as red meat, eggs, dark leafy greens and fortified cereals. Iron is absorbed into the body better when combined with vitamin C, so try eating these iron-rich foods with foods high in vitamin C, such as red peppers, kiwis, and broccoli.

5. Nausea

If you are feeling nauseous as a result of taking phentermine, firstly you should stick to drinking clear liquid such as water, as it is easier for your stomach to take and it will prevent dehydration. Nausea can also occur as a result of hunger, so if you know you haven’t eaten enough that day, try to eat something dry, like toasted whole wheat bread. Ginger is a great remedy for relieving nausea; studies have shown that it’s better than any anti-sickness medications you can buy at the pharmacy, so have some ginger tea or gingersnaps if you’re feeling nauseous. Mint tea also helps – the best way to make it is by adding a tablespoon of dry mint leaves to a pint of boiling water, leave it for about 30 minutes, then strain the tea and drink it.

These tips should help you to relieve the main phentermine side effects, which some people can suffer from as a result of taking phentermine. However, if these symptoms persist, or if they become particularly difficult to deal with, you must consult your phentermine doctor as soon as possible. If you are unable to continue taking phentermine due to the negative side effects, but still feel you could benefit from taking a weight loss supplement, Phen Caps are an ideal alternative as they provide the same appetite suppression and energy boost as phentermine, but have no known side effects.

We would love to hear from you if you have any comments or feedback about these tips for relieving the side effects of phentermine, or if you have any tips of your own that have worked for you, so please comment below!


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196 Responses

  1. I seem to get headaches from Phentermine. I only take half of the dosage per day…any feed back ?

    • Hi Rocky! You probably aren’t on phentermine anymore, but for anyone else with this same question: check our more recent blog article to read all about phentermine headaches.
      Rachel, phentermine.com

  2. I have been taking 37.5 mg once every morning for8days now. I have very bad dry mouth..all day and all night. I smoke cigarettes and it increases my desire for a cigarette immensely. I went from smoking one pack every 4 days to one pack every day. I haven’t been eating consistently because im on the go constantly on this medication that sometimes I cant remember when the last time I ate was. Tomorrow I will buy a journal and record everything. I am assuming I havent lost any weight yet because I havent been eating right so probably when I finally do eat my body immediately stores it as fat. I have yet to weigh myself though. I started on 2/13 at 218 lbs. I like the feeling it gives me…like energy to be active and it stops me from constantly obssessing and craving food allllll dayyy. But every time I eat something now (and it is a small portion every time) I am fine until maybe an hour or so after I finish. Then my stomach begins to make loudddd noises and I can feel the food I just ate digesting and moving through my intestines! It is so uncomfortable, and really loud! This lasts for an hour or more! I have never had this problem ever in my life….and I used to overeat until I could feel the skin on my stomach ripping into deep red stretch marks! And even then I never felt such uncomfortable digesting. What is this and is there anyone else who is experiencing it???

  3. What Id do is start drinking more water! I dunno if it’ll help or not but is try it

  4. I have been getting extremely dizzy. Couldnt figure out if it was this new nyc lifestyle, fast paced, not eating regularly, not drinking enough water… so I got off of them and ate regularly and drank water and symptoms seemed to fade. I got back on the pills a couple of days ago and what do ya know, fell completely dizzy all day today. I was very worried I would fall..

  5. I started out almost a month ago on Phenterrmine weighing 214lbs. I have done fine til yesterday and my stomach felt nauseated, so I ate. Now this is the next day and that same feeling is there. I have had water and some crackers and an egg. The scales now say 202. So the weight or water one is coming off. But, I don\’t like stomach feeling like this. Any ideas?

    • Hi Karen, nausea is generally a side effect that starts with the phentermine but then goes away after a few days or weeks. The fact that it has started late might indicate it is more related to what you’re eating or that perhaps you’re not eating enough. Are you eating at least 1200 calories per day and making sure to get regular meals with healthy carbs, protein, fruit and veg?
      Sally, phentermine.com

      • I just started Phentermine today. How long should this nausea last? I just feel sick at the stomach.

        • Hi Tina,
          Nausea is a common side effect but it generally only lasts the first few days. Nausea is usually related to food or a lack of it, so it might be a good idea to eat sooner after taking phentermine, because, while your body is getting used to it, the wait of an hour or two before breakfast can really irritate the stomach and cause this nausea. Hope that helps!
          Sally, phentermine.com

      • When I started taking Phen. I have noticed that when I go pee..it take a few seconds to get started…but before I started taking the Phen..I had no problem.. has anybody else had this problem.

        • Are you drinking plenty of water? That could be a symptom of dehydration.

        • Yes, that among other things has happened to me also.

  6. I have been taking phetemine 37.5 and I have recently started to develop a ache pain in my chest? Is this normal

    • Hi Charlotte,
      This is not a common side effect but it could be serious, you should talk to your doctor as soon as possible.
      Sally, phentermine.com

      • Charlotte, I also had a dull pain in the center of my chest for a few days. I’m unable to determine why I had it, however, to my understanding, phentermine has made me be bloated and have gas so I burp. This burping could strain the chest muscles. It’s a theory for both of us, but still don’t know. My previous ekg came out normal. Monitor your blood pressure and Do Not drink coffee close to taking phentermine.

  7. Thanks Sally, My sister in law has also been taking them
    And had the same effect on her after week and half , i have been taking them for only 8 days but over 2 weeks where I have had a few days break in between and haven’t had a appetite at all but falsed myself to eat where I have been feeling slightly weak and lack of energy when it hits the afternoon, I’ve probley had about 6000 cals in the space of two weeks which I know is bad but I just have no interest in food. So far I’ve Lost 12 pounds which I first started at 12.12 not weigh 12stone. I don’t think it helps I have been drinking energy drink which is one a day of a morning and maybe 1-2 zero coke a day as well.. Do u think the caffeine is maybe the problem, where it’s an over load of caffeine and the tablet combined x

    • Hi Charlotte,
      Energy drinks and diet sodas are very bad for your body and don’t help with your weight loss efforts either. Energy drinks have been known to cause heart problems too so this could definitely be a factor. But, I think the main issue here is that you should have more of an appetite by now. I would recommend that you halve your dosage by splitting your tablet in two and just take half for a few days to see how you feel. And, if you can’t face food at first then perhaps you could try making your own smoothies? My personal favorite is pineapple juice, frozen berries and a Greek yogurt, so you get fiber, protein and a much healthier energy boost too.
      Hope that helps!

  8. I have phentermine for 2 moths now I lost 20 pounds but my skin is dry and in my face I star ed to have like beads face and I already use creams but don\’t help…please if some body can help me to remove my beads face

    • Hey Jhon,
      I haven’t been able to find ‘beads face’ in an online search, is it a typing error, or could you describe what this condition is so we can see if we can offer you any help or advice. Thanks!

      Sally, phentermine.com

  9. Started phen 4 days ago. The first day I didn’t eat much so I felt horrible! I’m real sensitive to pills.. It got better after that but night before last, I almost dosed off but immediately had to sit up cuz it was just a rush of dizziness. Then this morning it was terrible! It’s ONLY when I roll over to my left side. Is it normal to get dizzy on just one side??

    • Hi Brea,
      Dizziness is a common phentermine side effect but I’ve never heard of people describing a dizziness only on one side. Is it possible that you have an inner ear imbalance or an ear infection or something?
      Sally, phentermine.com

  10. I just started taking 30mg Phentermine 5 days ago and it makes me feels horrible. I get an upset stomach, dizziness and hot flashes. I try to eat to see if that\’ll make me feel better, but I have absolutely no taste for food. What should I do?

    • Hi Latoya,
      Regardless of whether you have taste for food you have to eat as an empty stomach will only make the side effects harder to bear, and you also will find it hard to lose weight as your metabolism will slow down if you don’t eat enough. Drink lots of water and eat what you can eat, whether it’s a yogurt or some toast or a smoothie – like when you’re sick there should be something which you think you can manage and then take it from there. And, it could also be a good idea to split your dosage if you’re taking it in tablet form as this can make the first few days easier to bear until your body gets used to the side effects a little more.
      Sally, phentermine.com

  11. Been taking phentermine for over a month a month now and for the past week i have been getting light headed is this a normal side effect? Also have began exercising. And it just seems to come and go throuout the day

    • Hi Martin,
      Yes, feeling light-headed is a normal side effect. You should be sure to drink plenty of water, especially when exercising, and try to eat every couple of hours even if it’s just a small snack like a handful of nuts or a piece of fruit to keep your blood sugar levels steady. Feeling light-headed can also be due to low blood pressure, so if you have that already then you might be more likely to experience light-headedness with phentermine. A salty snack like some wholegrain crackers or some salted peanuts can help with this.
      Hope that helps!
      Sally, phentermine.com

  12. My only complaint is that towards the end of the day, i get such terrible migraines that i vomit. It only lasts for the first couple days when i begin taking them, but this makes me nervous about starting back up again, especially since im starting a new job in 5 days…

  13. I have been taking phentermine for a week now and I started feeling nauseous and dizzy three days ago, today it’s currently unbearable. Is this normal? I drink 3 cups of water had toast and lunch. I feel like I have to throw up. I usually have half of a pill but I figure I could start taking a whole one What should I do?

    • Hi April,
      If the side effects of phentermine are ‘unbearable’ as you say, this is a warning sign that there is something in them that is not agreeing with your body. You should speak to your doctor as soon as you can, but if you’re not able to get in touch with him or her then you should stop taking phentermine and wait to speak to him/her when you can. If half a pill is having this effect on you then you really shouldn’t increase your dosage.
      Sally, phentermine.com

  14. Hi, I’ve been taking 1/2 tab for a week. I’m still nauseous, especially when I work out. I’m eating and drinking plenty of water. Does this usually subside?

    • Hi Gina,
      Usually the nausea side effect does subside, but since you’re particularly affected when you exercise then it may be that you’re not eating the right foods and amount before you work out. This guide should help you get the right exercise fuel: https://www.phentermine.com/blog/workout-snacks-phentermine-weight-loss/ With respect to the nausea, if it doesn’t subside within another week then we would advise you to speak to your doctor.
      Sally, phentermine.com

  15. I’ve been taking Phentermine 37.5 for about 6 months with my family dr supervision (monthly appointments). Everything has been great. I’ve lost a lot of weight and feel great. The last few weeks I have been feeling nauseous. It starts in the morning as soon as I start moving around. It will go away and come back throughout the day. I think it is because I have lost interest in food. I don’t think I am eating enough. I can’t have carbs/gluten due to other issues. Any suggestions?

    • Hi Val,
      Yes it definitely sounds like this nausea is because you’re not eating enough – you need to eat at least 1200 calories a day of healthy nutritious food, hungry or not. Phentermine is an aggressive medication, so if you’re taking it and eating very little then your body will react in this way. If you can’t have gluten because you’re celiac then you can still have carbs but just without gluten – carbohydrates are an essential part of our diet and provide energy for our bodies and brains. If you’re not celiac or don’t have a diagnosed intolerance then there is no reason you shouldn’t eat gluten – there is nothing in gluten that is bad for the average person. This article explains more: https://www.phen.com/how-to-lose-weight-phen-blog/what-is-gluten-should-i-avoid-it
      Sally, phentermine.com

  16. I been taking phen for over a month and it makes me hungry and I get up and go in the morning but am overtired around four in the evening I drink tons of water everyday all day cause I don’t wanna eat so much any advice for me

    • Hi Miriam,
      It sounds like phentermine really isn’t working for you if it makes you hungry and tired. We would advise you to speak to your doctor to find out if there is anything else that might work better for you.
      Sally, phentermine.com

      • I started taking 30 mg 4 days ago. and I am experiencing the same feeling of hunger and if I don’t eat the weaker and the more tired I get and as soon as I eat I am fine for about an hour if that. Watch me gain weight on this lol

        • Hi Diana,
          If you think that phentermine is actually increasing your appetite then you should talk to your doctor – it could be that the dosage is too strong for you or just that phentermine isn’t suitable for you.
          Sally, phentermine.com

  17. I started taking phentermine Dec 24, 2014 i took it until February of 2015 lost 29lbs I had absolutely no side effects. My doctor prescribed it to me again Dec 31, 2015 and this past week I’ve been feeling nauseous, light headed, and headaches the symptoms occur off and on throughout the day. I really like the results that it gives me, but the side effects 🙁 What should I do???

    • Hi Deedee,
      It can happen this way that phentermine has no side effects and then another time it does, so this is quite common with many of our forum users etc. If you’re on high dosage such as 37.5mg and taking the tablets then you could try halving them to help your body get used to the phentermine more slowly, and then increase your dosage after a week or so. Otherwise, it could be that you’re not eating enough or not drinking enough water so be sure to have regular small meals and snacks and to drink plenty of water throughout the day.
      Sally, phentermine.com

  18. 250 lbs November 15, 2015. Presently January 2, 2016 225 lbs. I’m very pleased with my weight loss. Good is not my focus any longer. For the first time in my life, I plan what I’m going to eat. Since I’m not hungry, I have to plan meals so I will eat. In 2008 at my peak weight of 330 lbs size 26-28, I underwent gastric bypass and lost 136 lbs in six months. I was at 194 lbs wearing a size 12. I was very happy. Seven yrs later gaining 56 lbs I was upset with myself for letting that happen. Phentermine is helping me gain control over food. I only eat when I need to, breakfast, lunch then dinner. Light meals, because once again I’m not hungry. I’m only eating because I need to. My main side effect is dry mouth with mouth ulcers. I can deal with that. I’m drinking water like crazy. A good thing. Instead of buying new clothes, I’ve been taking them in with the swing machine. I’m wearing a 14 in jeans but taking them in weekly 😆. Co-workers are asking me how I’m losing and I’m happy to tell them, it’s Phentermine.

    • That’s great Rosanna, we’re really pleased for you, WELL DONE!!!
      Sally, phentermine.com

  19. I started taking phentermine 1/2 a pill but i feel very dizzy, is there something i can do to not feel this way?

    • Hi Maria,
      Yes, you can help to ease this symptom by being sure to drink lots of water, cut down on salt and caffeine, eat every 2-3 hours and get plenty of foods rich in iron and vitamin C.
      Sally, phentermine.com

  20. I have been taking phenteine for about 3 weeks. I starting to have numbness mainly on my right side in my arms, legs, and feet. Sometimes it is on the left side but it is mainly in the right. The numbness and tingling comes and goes but it had been on and off for the past week. I have also had numbness in my face. Is this a normal side effer t or should I be worried?

    • Hi Pam,
      Numbness isn’t listed as a side effect of phentermine but it does sound like it could be related and potentially serious. We would therefore recommend that you speak to your doctor as soon as possible as this is not something which can be ignored. Best of luck.
      Sally, phentermine.com

  21. I started taking Phentermine 37.5 a couple days ago and the only side effect I have other than a slightly zoned out feeling is irritability, I have found that I become very short tempered around 3 o’clock. Is there anything I can do to combat this?

    • Hi Jessica,
      Side effects like irritability are quite common with phentermine as it has the effect on the body of amplifying emotions, both good and bad. As you seem to experience this particular feeling more around 3pm, it could be a good idea to prepare yourself for it mentally around 10-20 minutes before, by taking some time out to employ one of these stress management techniques: https://www.phentermine.com/blog/de-stress-for-phentermine-weight-loss-success/ If you’re working it might be more difficult, but a quick 5 minutes to yourself away from the stresses of everyday life should at least reduce this side effect for you until your body adjusts to the changes caused by phentermine. Hope that helps!
      Sall,y phentermine.com

  22. Hi there,

    I have been on and off phentermine for a couple of years (under supervision of my endocrinologist). The last batch I received made me very sick to my stomach – dry heaving, the whole nine yards – it was so bad I thought I was pregnant and experiencing morning sickness! This is not something I’ve experienced before and the brand has not changed.

    Do you know if perhaps the formulation has changed and this could contribute to this issue? The brand my pharmacy uses is KVK Tech Inc, 37.5 mg.

    After the first Rx (four years ago), I lost 40 pounds almost immediately however I am not losing weight on it any longer, which is frustrating. It’s preventing me from gaining weight however, so my endo is happy with continuing the Rx. (I have been off for periods of time, usually six months)

    Have you experience someone who had not lost weight? Any clue what I might be doing wrong?


  23. I started take Phentermine 4 days ago. My Dr. has me doing 30 days of HMR 800 supplement shakes 5 times a day instead of food. I have better very dizzy, irritable & nauseous. I’m wondering if the supplement shakes aren’t providing the nourishment my body needs while on the phentermine.

    • Hi Trisha,
      We wouldn’t recommend supplement shakes while taking phentermine. As you say, they probably aren’t providing the nourishment your body needs, and when you’re taking an aggressive drug like phentermine, this is only going to make the side effects affect you more. In addition, this kind of plan deprives you of the opportunity to develop healthy eating habits, which is the key to long-term goal weight maintenance. Our advice would be to speak to your doctor and see if he or she has an alternative plan for you which involves healthy balanced meals instead of these shakes.
      Sally, phentermine.com

    • I\’m noticing the same also

  24. Sensation of cold feet it is driving me nuts – I stopped the phen four days ago to see if it stops. I went to the doc and my pulse and circulation is fine.
    Help! Anyone dealing with this?

    • I am looking for answers to this as well!!

  25. Hi Good morning people. I have taken phentermine in the past about 6 years ago. I did loose weight and now back on them to try and shed a few pounds. One bad thing….I’m hating the side effects!!! I am very moody and emotional and pick fights with my boyfriend and have a bad crash. Does anyone have these bipolar side effects with phentermine 37.5? If so what can I do to help stabilize myself while taking them??Help!

    • My husband was taking phentermine ang he has this symptoms too. He just argues for any little thing he’s always saying I’m not giving him space he’s in a bad mood all day to the point that it seems like he can’t stand me anymore, he’s forgetting things he does or say, he allusinates I’m watching everything he does,he says he’s never been completely happy. He is a totally different person. I really need help this is destroying our marriage. He stopped them last Thursday I’m just hoping they wear off soon, but now I’m confused if it was the effect of the pill or he just doesn’t love me anymore. Although he’s never said he doesn’t he keeps repeating to me I do Love you I just need my space. When we don’t even eat, sleep together anymore.

  26. Hi I have been taking this for 2 days. The first day I took a quarter of the pill. Although it made me feel high And ate less. By the evening I was hungry and I had insomnia. The next day I took a half a pill. Wow it felt great and I didn’t really eat much but by night I was feeling sick and. Although I was tired. I could not sleep. Is this normal. Can I just take a quarter and that be enough. I don’t want to feel sick and I sort of feel palpitations. Any suggestions? Oh yea. My dry mouth is annoying. I tried adding lemon to my water for the quench. Didn’t work.

    • Hi Samia,
      If a quarter works for you then this is fine, especially to start off with – many people find that a whole pill is too much at first, but within a few days they find that they can take a whole pill without problems. In your case it sounds like you’re a little more sensitive, but there is no reason why you should take a higher dosage than you feel comfortable with. As for the dry mouth, we recommend Phen Drink, which includes saliva-boosters to stop the symptoms of dry mouth better than plain water can. Here’s a link to find out more: https://www.phen.com/phendrink
      Good luck!
      Sally, phentermine.com

      • Hi Sally
        Can you address the palpitations, as this is the only adverse effect I experienced at night. I began my weight loss treatment on Tues 3-29-16, for the first time I felt the palpitations last night, 4 days after beginning Phen HCL 30mg daily. I have occasional elevated pulse during the day 124-135, which I can control by staying active and controlling my breathing. I am glad I found this blog to read others concerns and your recommendations.

        • Hi Priscilla,
          An elevated heart rate is normal with phentermine, but if you experience an irregular heart beat or fluttering heart beat then you must tell your doctor immediately, as these are signs of a potential risk to your health.
          Good luck with your weight loss journey and stay safe and healthy!
          Sally, phentermine.com

  27. Hi there, I started taking phentermine on 3-25-2016, but I am still eating, it did not suppress my appetite at all, am I supposed to wait a little longer for it to start working?


    • Hi Angie,
      You should still have an appetite and want to eat, but it should be less than before. If it’s not working for you at all maybe your dosage is too low. I would advise you to speak to your doctor to see what he or she recommends.
      Sally, phentermine.com

  28. I started phen. 37.5 exactly 3 weeks ago so far I have lost 15 pounds! I’m very happy with the results so far however I do have one concern. I can tolerate the dry mouth by drinking at least a gallon of water through the day and chewing gum helps but I’ve literally lost my sense of taste!!!! Is this normal?

  29. I’m concerned I keep reading people complaining about dizziness, which can be due to low blood pressure. The side effect of dry mouth is so we can drink water so we can hydrate properly but there is such a thing as over hydrating, make sure you are only drinking half your weight in ounces. Example: weight of 200 lbs drink 100 oz of water, so you don’t flush out your electrolytes in your urine. This is why Sally stresses the importance of balanced meals.

    • Thanks for your comment Priscilla, what you say is very true!
      Sally, phentermine.com

  30. If I threw up about 20 minutes after taking phentermine, will it still work?

    • Hi Eve,
      It’s difficult to say as it depends on how quickly your body metabolizes medications, but if it does have some effect it may be reduced since it’s likely that your body was not able to absorb all of the contents before you were sick. Your doctor should be able to give you a more definitive answer, but if this sickness is something that you’re experiencing a lot on phentermine then it might be wise to speak to your doctor anyway as this could be a sign that phentermine isn’t suitable for you.
      Sally, phentermine.com

  31. I’ve been taking phen for 3 days now. I took 1/2 pill the first two days and a whole pill today. I’ve been feeling like I’m loaded for 3 days now, like Vicodin does to you. Nervousness, moody, thirsty so I drink lots of water and have to pee every five min. Appetite is decreased. Couldn’t sleep last night. I’m hoping these side affects go away soon. Find it hard to think sometimes.

    • I get the same “loaded” feeling and I don’t know what to do about it. I love that it helps me not over-eat but I can’t stand the feeling I get. Are you still having this feeling? How long have you been taking phentermine?

  32. Day 8 and the past 3 days I feel like I’m having a hard time breathing, but my chest doesn’t hurt and my oxygen levels are great, dizzy and horrible dry mouth. Also it has NEVER given me energy since I started, it’s actually made me more tired. Anyone know why this might be??

    • Hi Chris,
      We’re actually publishing an article tomorrow explaining why some people feel more tired on phentermine. Hopefully you will find it useful!
      Sally, phentermine.com

  33. I have taken Phentermine before and it worked wonders. I had planned on keeping the weight off and I was UNTIL I got a boyfriend who eats almost every hour (he has a really high metabolism). I gained all the weight back plus some. I started Phentermine again and I’ve been on it for a little over a month and it’s nothing like it was the first time. I took it one day and got so busy with work I completely forgot to eat, got home and wasn’t able to eat until 9:30pm. Since then I feel like my stomach swelled up and has yet to go down. I feel nauseous every time I eat anything whether it’s an apple or some cheez-its. I’m wanting to know what is going on. Thank you!

    • Hi Kaitlyn,
      It sounds like the appetite-suppressing effects are a little too strong for you this time round, when it is normally the opposite. I would advise you to take just half a pill and see if your appetite is a more like it should be.
      Sally, phentermine.com

  34. Hi,
    I just started half pill this morning 7am. Felt great, Worked out hard, drank lots of water ate not as much as I should have but still some. Then about 4 pm, got really sick vomiting/dirreah and nausea, almost flu like.
    Am I actually sick or can this side effect show up 8-9 hours later?

    • Hi Amber,
      Although nausea is a side effect of phentermine, diarrhea and actually vomiting aren’t typically associated with phentermine. It could be an allergic reaction however, so I would advise you to speak to your doctor.
      Sally, phentermine.com

      • Why was this stuff ever made it\’s horrible and should be made Illegal . I took it for one day dizziness puking sweating irritability … not good

  35. I been taking phentermine for about 6 days now I lost 8 pounds but since yesterday while working out I felt really dizzy I thought maybe because I was on the treadmill but today in the morning I got really dizzy also not as bad as yesterday but will this go away? How long does the dizziness side effect last?

    • Hi Erika,
      The dizziness usually starts to subside after the first week or so, but you can help to avoid this by being sure to drink lots of water and eat every 3-4 hours – getting dizzy while exercising is usually due to a lack of water or food. If you’ve ever suffered with dizzy spells or low blood sugar then a salty snack such as a handful of salted nuts can help to even your blood sugar levels.
      Sally, phentermine.com

  36. Hi i been taking phen 37.5 for 4 days now and i notice my glands under my neck is swelling and i could use some advise as to how to get rid of the swelling. Its annoying.

    • Hi Crystal,
      Swollen glands isn’t a side effect of phentermine, so if you think it is related or some kind of reaction then we would advise you to speak to your doctor.
      Sally, phentermine.com

  37. I have been taking phentermine for 6 days now and while I do occasionally suffer from anxiety my doctor did state this can make it more noticeable or flare up. But i have been able to kinda cope with it but last night I started to feel like i had to vomit and this morning I had to take my time getting out of bad. Today I took a half of a pill and a few hours later I felt very sick and had to vomit and use the rest room. After lying on my desk for a few mins and eating crackers I felt a little better but I’m very hesitant to eat anything on my lunch as my stomach still feels upset.

    • Hi Ebonie,
      I’m sorry to hear that you’ve been suffering on phentermine. Although you might be wary about eating anything, it’s always best to try and line your stomach as phentermine can aggravate it, and taking phentermine without eating is likely to make any side effects worse, especially nausea and dizziness.
      Sally, phentermine.com

  38. Okay so i just started this meds like two almost three days ago and im fine til one or two in the afternoon then my mouth is so dry and i get a headache and feel like i need to lay down cuz it feels like im coming off the energy high and makes me feel wired will it stop or what should i do i drink like 6 to 8 glasses a day so and im getting ready to start a new job and i dont want this stuff to happen to me around other people and think im weird or cant handle the job please help

    • Hi Danielle,
      Drinking plenty of water will help with headaches and dizziness, so keep up the 8 glasses a day, but also be sure to eat every 3 hours or so as not eating enough can also add to side effects. Phen Drink can help with the dry mouth, here is the link for that: https://www.phen.com/phendrink, and lastly, if you feel that maybe the dosage you’re taking is too strong, then many people find it helpful to split the dosage for the first few days until they get used to the side effects more.
      Sally, phentermine.com

  39. Hi- I just started taking this and I’m really bloated now. Is there anything I can do or take?

    • Hi Sandy,
      If you mean that you have constipation then we would advise to drink plenty of water, cut down on coffee, and to slowly introduce fiber to your diet – if you’ve eaten a lot of fiber in one go and it’s not something you usually eat then this could also be a reason for feeling bloated.
      Sally, phentermine.com

  40. I started taking this med 6 days ago half a pill 37.5 had no side effects except dry mouth, but yesterday morning and this morning I took a whole pill and feel so tired and I did not eat from first day until today maybe all together 1500 to 2000 calories for 6 days
    I know it’s not good but just don’t have appetite but do drink at least 7 bottles of water a day

    • Hi Amber,
      Firstly, you have to eat more – no appetite or not, this is not the way to lose weight – your metabolism will shut down and when your hunger comes back, your body will convert food to fat. If a whole pill is too strong for you, take half a pill and then maybe the appetite suppression will be less aggressive and you’ll be able to eat – the bare minimum is 1200 a day, so you’ve eaten less than two days worth of calories in 6 days. Lastly, you said that you drink seven bottles of water a day but this may be too much, depending on the size of the bottles – you should drink around 2 liters or 8 glasses of water a day – a little more than this is ok but it’s important not to drink too much water as it can cause natural salt levels in the blood to drop which can be dangerous.
      Sally, phentermine.com

  41. Hi every 1 its been 2 weeks now taking phentermine 30g a day im experiencing swollen glands in my mouth and salty taste of my saliva its uncomfortable any 1 pls advice

  42. Hi. Im taking 30mg and the only side effects i get is late at night when i go to bed. I feel funny and light headed. I get cold body chills and i feel scared to fall asleep. Its a very scary feeling. I eat 5200 kj a day and drink about 1.5 litres of water daily. Any suggestions?

    • Hi Lucy,
      Your calorie intake sounds fine, although this is close to the minimum amount for an adult female so if you are tall, very active, or at a high current weight then you might need to eat more than this to sustain yourself. Your water intake could be a little higher – 2 liters per day would be better, especially as phentermine is very dehydrating. Feeling light-headed is usually due to a lack of food or water, a hot environment or some kind of over-exertion. To avoid this, try to maintain a steady intake of water throughout the day and keep to smaller mini-meals to keep your blood sugar levels steady. If you suffer with low blood sugar then a salty snack such as a handful of nuts or some peanut butter can help to make you feel better.
      Hope that helps!
      Sally, phentermine.com

  43. Hi I have been taking 30mg phentermine for 8 days but I don’t see any weight loss yet. Also my blood sugar has been all out of whack, yesterday I thought my blood sugar was going down because I was really shaky and irritable but it was 249 seriously what is going on?? Please you have any suggestion for me.

    • Hi Dorothy,
      Is phentermine helping you to exercise and eat better? This is what leads to weight loss, so if it’s not having those effects for you then that might explain the lack of weight loss. As for the feeling shaky and irritable, these are side effects of the phentermine so they are quite normal and should start to reduce in the next few days.
      Sally, phentermine.com

    • Hey Dorothy, I am a diabetic and my blood sugar has been sooooo crazy, mainly very high since started on phentermine 30gm, 3 days ago. Despite low carb, low sugar eating. It has suppressed my appetite so I am definitely eating less but suffering from extremely high blood sugars. Most feedback is that phentermine reduces blood sugar levels. I’m struggling.

  44. I started taking Phentermine 37.5mg back on 5/8/16 and am currently down about 15lbs. The only problem I’m having is that I constantly feel nauseated and extremely dizzy all the time to almost the point of passing out. Is there anything to do to stop those symptoms?

    • Hi Adrienne,
      Nausea and dizziness on phentermine are common side effects but they usually only last a week or two, so if your symptoms are still quite severe then it may be more related to what you’re eating and drinking. Phentermine is very hydrating so you should be sure to drink 2 liters of water a day – but, too much water can cause a reduction in salt in the body so it’s not a good idea to drink too much. If you haven’t been drinking enough water or if you’ve been overdoing the water then these could be reasons for the dizziness. You should eat every 3 or 4 hours to ensure you have a steady blood sugar level, and if you are exercising then you should wait enough time for your food to go down before you work out – the length of time you should wait depends on what you’ve eaten. Make sure that you’re eating enough calories and enough carbs too – low carb diets often cause dizziness due to a lack of glucose feeding the brain.
      Hope that helps!
      Sally, phentermine.com

  45. I started taking phen, 6 days ago 05/27/16. I was fine the first couple of days & had not experience any bad symptoms before while taking phen.. Today on day 6th I have experience dizziness , dry mouth , constipation & have a really high fever. Do you recommend me to stop taking them & why do I have a fever?

    • Hi Genesis,
      The dizziness, dry mouth and constipation are all common side effects of phentermine so if these are not too uncomfortable then we would just advise you to keep taking the phentermine, although if you’re taking phentermine in pill form then it could be a good idea to halve your dosage until you get more used to the side effects. The fever isn’t a typical phentermine side effect, although a flushed complexion and feeling hot are, so if this subsides then it is nothing to worry about, but if the fever continues then it could be that you are coming down with something like a cold or flu.
      Hope that helps!
      Sally, phentermine.com

  46. I’ve been on this medication 2 weeks going on 3 and I’ve only had 3 small bowel movements and that was because I took laxatives. I have no urge at all to go. Does anyone else have this problem? Also, how long can this go on before it becomes a major problem?

    • Hi Karen,
      It sounds like you are experiencing extreme constipation, and while it is one of the most common phentermine side effects, it is a cause for concern that you have barely had any bowel movements in close to 3 weeks. We would advise you to slowly increase your fiber intake, drink at least 2 liters of water a day, avoid alcohol, and limit your intake of caffeine. If you are taking the phentermine tablets then it could be a good idea to halve your dosage for a few days so that your body can get used to the effects more.
      Sally, phentermine.com

  47. I started taking phentermine and the 2nd day I started having severe headaches. Day 6 tried 1/2 a pill and still severe headache. I get the headache within a hour of taking it and it stays all day. I drink a gallon of water a day and eat 3xs a day. Tried ibuprofen and tylenol neither helps. Will this go away because I’m unable to work out. Any suggestions

    • Hi Stacy,
      It sounds like you’re having a strong reaction to the phentermine, and if even half a pill is leading to a severe headache then it’s clear that it’s not just related to the strength of the dosage. It could be a sign of an allergy to the medication so I would suggest you speak to your doctor to see if he or she could recommend anything different to help you lose weight, whether that’s a different brand or manufacturer, or maybe a different diet pill altogether.
      Sally, phentermine.com

  48. I began phentermine the end of January, and lost 25lbs. I’ve experienced minor headaches and insomnia. I also get different levels of dry mouth. I find it makes me drink even more water, which can’t be bad. I also use Biotene mouth wash or spray, an OTC mouth lubricant which helps. For me, the minor side effects have been worth the results. I hope to lose 10lbs more.

  49. I start phen 5 days ago lost 10 pds
    No side effects except some days esp in afternoon get so tired feel like I’m going to pass out
    I sleep well, no headaches

  50. What causes me to feel so tired??

  51. Started taking Phentermine 37.5 mg and didn’t have any side effects. However, I am a diabetic and ended up in the ER with insulin shock. I stopped taking it after that as when I researched it, a few articles did say it can lower sugar levels. But ever since I stopped taking it, I now have indigestion and constipation and when I do go, the stool is almost black. It’s not blood as I tested it to make sure and again read that Phentermine can make your stools dark. Anyone with diabetes should be very wary of this medication and ensure you check your blood sugar often.

    • Thanks for the information Kathy, this is very important for phentermine users with diabetes to bear in mind.
      Sally, phentermine.com

  52. i started 6-8-16 . i was wondering if bloating is a side affect? i am also having hot and cold sweats and some headaches

    • Hi Angela,
      The headaches are a common side effect of phentermine and some people can experience an increase in body temperature with phentermine so this is also quite normal. The bloating is more likely to be related to your diet than the phentermine, so it might be a good idea to take a look at any foods which you have recently introduced to your diet or foods you are consuming more of than you used to, especially if they have a high fiber content.
      Sally, phentermine.com

  53. Hello, I started phentermine prescription 2 days ago. I have had dizziness and extremely high energy. I feel the appetite suppressant part working for sure. Today (day 2 of phentermine) from about 9:30am to about 8:30pm I ate only 910 calories, a little diet pepsi, and two huge bottles of water (24oz ea). Right about 9:30pm tonight I got CRAZY jitters and dizziness. I recently had vertigo a month ago too and this side effect makes me kind of nervous because I still get an imbalanced feeling in my head every now and then since my vertigo. So I ate a little more food and waited 20 minutes after to see if the jitters would calm down and they didn’t so I ate a little more and it finally went away around 10pm. I knew these side effects before I started taking them. in my first 2 days I’ve taken 2 whole pills. I decided that the side effects were a little bit too strong for me so I want to cut them in half and just take half a day for a while. My questions are:
    1. Will the phentermine still be as effective in suppressing the appetite through out the day as it is with a whole pill?
    2. Is this a pill that after some time the body adapts to the side effects and they won’t be a bother anymore?
    3. Is cardio safe to do while taking phentermine? Since it’s a stimulant I am super nervous about how it makes me feel just sitting, strong pounding heartbeat and warm and a bit sweaty, so I’m afraid just by that to get my heart rate up too high and have something bad happen.

    • Hi Macie,
      In answer to your questions:
      1) Taking half a phentermine is a good idea at first, especially if the side effects are too strong for you. It’s likely that the desired effects of energy and appetite suppression will also be lessened with just half the dosage, but both effects should be sufficient for you to be able to eat healthily and exercise to get started.
      2) Yes – your body gets more and more used to phentermine as time passes, which on the plus side means that the side effects should start to bother you less, but it unfortunately also means that the desired effects often reduce too. If the side effects don’t start to reduce after the first couple of weeks and are particularly worrying or painful then you should consult your doctor to see if phentermine is right for you at all.
      3) It’s fine to do cardio while taking phentermine – if overheating or a very rapid heartbeat are issues for you then try to ease into the cardio workout by warming up and gradually building up your pace. Making sure that the room is well ventilated helps, and be sure to drink water throughout too, so you don’t get overly dehydrated.
      Hope that helps!
      Sally, phentermine.com

  54. I’ve only started taking phentermine 2 days ago the first night I had heart burn and couldn’t sleep, today is the second day that I took it, I was fine in the morning but later in the evening I developed a bad headache was nauseous and dizzy. My chest started aching and I felt like my heartbeat was going at a fast pace when I lay down but I checked my pulse I was at 87 a min Then I have a burning in my throat to my stomach. Is this normal, should I wait to consult my doctor or is it something that will fade away. I’m only 19 and weigh 180

    • I started taking it 2 weeks ago. First week perfect. Second week, every evening about 1 hour after dinner I get horrible stomach pains. This could be heartburn? I’ve never gotten it before. I tried a 1/2 pill and still got it. I have lost 9 pounds, and don’t want to stop, but the pain is unbearable.

      • Hi Jen,
        Usually heartburn or indigestion is located more in the chest area rather than in the stomach. We would advise you to go to your doctor about this pain as it is not a usual side effect of phentermine.
        Sally, phentermine.com

  55. What is the ingredient in phen caps that gives you energy? Does it also boost metabolism?

    • Hi Kelly,
      The stimulants in Phen Caps are theobromine and caffeine, so these are the main ingredients which boost energy. They also contain ingredients which helps to boost metabolism by creating a thermogenic response to effectively heat up the body and improve the way the body converts food into energy instead of storing it as fat. You can read more about the specific ingredients and how they work here: https://www.phen.com/how-to-lose-weight-phen-blog/how-do-phen-caps-work
      Sally, phentermine.com

  56. Hi! I started with half a dose for one week two weeks ago, then last week went full dose and was fine, if a little extra jittery since I was still drinking coffee. I skipped Sunday and then took a full dose on Monday and felt dizzy and kind off for most of the day. Later in the day at dinner I was sitting down and I felt faint. It feels a bit like my heart is beating faster than normal, but I haven’t gotten it checked. I opted to skip Tuesday and Wednesday to see if I’d feel “normal”, but now I just feel extremely tired and really spacey, almost like I’m here but not here if that makes sense. Not sure if these effects warrant medical attention or if this is normal.

    • Hi Margartia,
      The symptoms you’re describing aren’t uncommon but it could be a good idea to speak to your doctor to discuss how skipping days might have affected you and how to proceed in the future. He or she might agree that it’s best to stick to half a dose while you feel that it is still working for you as it sounds like a whole pill is too strong.
      Sally, phentermine.com

  57. HI i started taking the 37.5. After 8 days I felt very dizzy. But what worries me the most is the chest pain and it is making me so uncomfortable. I feel like vomiting. I stopped the caps 2 days ago but the dizziness and the chest pain just won’t fade. I did not consult any doctor as I bought this online. Will the pain go away? What should I do?

    • Hi Tina,
      It’s unlikely that what you bought is actually phentermine but it sounds like you are having a very bad reaction to whatever it was you took. Chest pains are a sign of something serious and should not be ignored, especially if you are still suffering despite ending the medication. You should go to your doctor with your symptoms regardless and explain that some supplements you bought online are the likely cause. No matter what your doctor thinks of online supplements or your decision to take them, your health comes first so he has a duty of care to treat you.
      Sally, phentermine.com

  58. I have taken this for about a month and a half. It really does help if you stick with your diet. My only question is how does everyone else control the hot flashes? I get them quite frequently and I sweat so much it’s embarrassing!!

  59. I have read these side effects and I’m nervous to try it, although I was hoping to. I have friends who have used it with these same side effects, but great results. Does it help if I start with half a tablet, and if so, how long should I only take half before taking the whole tablet?

    • Hi Brooke,
      The best thing to do is see your doctor to see if phentermine is right for you. If it is then your doctor will prescribe you the dosage best suited to you, but if you do find that it is too strong, splitting your pill can help your body get used to the effects. You can ask your doctor for guidance but most people find within a week or two that they are able to move up to a whole pill without an increase in side effects. However, if you find that half a tablet works well for you in terms of energy and appetite suppression then there’s no reason why you can’t continue taking half a pill.
      Sally, phentermine.com

  60. Day three on Phentermine and all in all, I’m feeling okay. I don’t get dizzy..but a little lightheaded which I found goes away when I eat a little something. My struggle is sleeping and a headache. I took Advil for the headache which made me feel yuck but it didn’t touch the headache. Excedrin always helps me but I’m afraid to take it with the caffeine in it. I’ve tried the sleepy time tea and bath at night and I fall asleep, but I can’t stay asleep. What can I do about these two issues?

    • Hi Lori,
      Personally I always favor ibuprofen for any aches – it’s much more effective as it reduces swelling as well as blocking pain receptors. Take up to 600mg every 8 hours but don’t exceed this dosage, and remember to take ibuprofen after eating to avoid stomach upset. You should also be sure to drink lots of water as the main reason that phentermine causes headaches is because it is very dehydrating. The insomnia you’re suffering from is very common on phentermine. You can try reducing your dosage for the next few days to see if that helps with the adjustment period, although this is only possible if you are taking phentermine in pill form as they can be broken in half. These side effects should start to wear off over the next few days even if you are unable to reduce your dosage though, so unfortunately it may just be a case of waiting for these symptoms to subside.
      Sally, phentermine.com

  61. I started taking phentermine almost 30 days ago I weighed 247 lbs and I\’m down to 225 it makes me really gasey loose bowel movements but the best thing about it is I’m not eating as much no other side effects

    • Did these symptoms ever go away? This is my second time taking this med with many years between. First time it constipated me, this time I have horrible, gas and lose bowels. Please tell me this subsides after a few weeks, most info I find online is people experiencing constipation, not diarrhea.

  62. Hello,

    It is my first day taking phentermine. I started at 7 am after breakfast, now at 12 pm i started feeling dizzy, lightheaded, heavy on back of my neck and my vision quite blurred. I find it bearable, because earlier my only concern was heart palpitation. I don’t have all that as yet. I feel quite relaxed. I observe my water intake and food too. So for the headache, can i take paracetamol? Will it help to reduce the dizziness by taking other med? Any other suggestion to reduce the effect?

    Thanks, Nia

  63. I just started it yesterday and it has killed my appetite which is good but I have to pee all the time and being a truck driver that’s no good. I’m afraid that I won’t be able to continue to take it.

    • Why don’t you buy a urinal….I was a nursing assistance once…an if I was a guy that’s what I would do!

  64. I have been on it almost 33 days and my mouth is so dry & my left cheek in the bottom of my mouth the gum is swollen & very sore the lower part of my mouth. When I was taking this & the thyoriod together my throat would be so hard to swallow, so I quit the only thyroid & and it is better but my bottom gums are very sore & sensitive on the left side of my cheek. I feel better when drinking something but it seems to inflame every day after a while after I have taken my pill. Wonder if I am allergic to it or if this is just a side effect

    • Hi Cindy,
      It sounds like you have the dry mouth side effect very bad. Dry mouth means a lack of saliva in the mouth which can then lead to sore gums, infections and sensitivity. You should speak to your doctor to see if he or she can recommend some kind of remedy for dry mouth.
      Sally, phentermine.com

  65. I started taking Phen 3 days ago and my headaches are outrageous… I remember when I took this 17 yrs ago the only side effect I got was dry mouth.. I seem to have both now.. But anywho, I carry headache powder with me everywhere and in a matter of 5 min it wipes it out completely! Good luck, here’s to prayin I lose this weight again!

  66. I have been taking phentermine for about 6 weeks now and I have decided to stop. I feel extremely tired and I have a strange feeling in my stomach..it isn’t nausea or pain..just strange discomfort. My main concern is what this med can do to my heart..I feel very strange. I have lost 10 pounds which for me is a miracle because I have tried so many things and nothing worked but I feel something is wrong with this medication but I can’t tell what it is. I also have tooth pain which I’ve never had before. Would love to hear from you, your thoughts on this. I really don’t want to stop taking the med because it helps but I am afraid of its long term consequences to my health.

  67. I’ve taken phentermine for a month and 1/2 with no major issues but one that I think may be linked to the pill. On 3 occasions my lips were swollen a bit. Nothing too noticeable but swollen nontheless. At first I thought it was a reaction to a new lipstick then I thought maybe my chapstick but the last time it seemed to be in relation to the pill as I had not used any products on my lips. I find it odd that an allergic reaction would only surface rarely in the time I’ve taken it. I do believe on those occasions I was drinking much caffeine. Do you think the caffeine had an impact on the lip swelling or was it just the meds? I’d like to take the meds but want to be safe. Is it possible to take a benedryl with the pill to counteract any swelling or would they just cancel each other out? I talked with my dr and she said stop immediately but didn’t give much thought about it or discussion. I’d like to know if anyone else has experienced this and your thoughts about continuing the medication safely. Thanks!

    • Hi Leela,
      I haven’t heard of this exact reaction before but it sounds like you are allergic to phentermine. Allergies to phentermine usually occur in a rash but lip swelling is also indicative of an allergy. Your doctor should have explained further but it sounds like it could be inadvisable for you to take phentermine as it could result in more serious allergic reactions, such as difficulty breathing or throat swelling. It could also be an allergy to caffeine though as allergies can develop at any time in your life so one way to check could be to stop taking phentermine and see if it continues when you drink caffeine.
      Hope that helps!
      Sally, phentermine.com

  68. I have been on 37.5 since Sept 1 2016…I did do half for two weeks. I have lost 20lbs so far….about 15 to go. I only had the dry moth til now. I now have dizziness. I have a feeling of being out of breath in the am. This is after sitting drinking my coffees …which is at least a hour….Why would it start now? I have been following a low carb diet…because I’m not hungry it has worked.

  69. This has also managed my IBS because it has slowed down my digestion so much. Or maybe because it’s better because I’m eating less. Anyone else with IBS having this result??

  70. I’ve been on 37.5mg for five days and the only side effect I feel is a mild headache but also more like pressure in my head. Is that common?

    • Hi Darin,
      Yes headaches are very common phentermine side effect. The main cause is the way phentermine dehydrates the body so be sure to drink plenty of water throughout the day.
      Sally, phentermine.com

  71. I can’t get past the taste of the pill as it melts on my tongue. I have tried drinking water during and/or after, but that hasn’t seemed to help. Would taking a calcium/ heartburn pill negate the effects if I take them at the same time? Or is there something else that will help with the initial taste?

    • Hi M,
      Unless you’re taking Suprenza, which is a dissolving tablet, you’re supposed to swallow the pill whole, not let it melt on your tongue.
      Sally, phentermine.com

  72. I’ve been taking half a pill for 3-4 weeks. I’m also on a 21 day cleanse. I just now started having dizzy spells. Things go black..then I come out of it before I pass out…maybe 4 times it’s happened. I feel fine though. Think I need more water…the dry mouth tho, yeah that’s baaaaaad

  73. I have taken Phentermine before and the side effects are different now than they were then. Back then I went from 180 pounds to 142 pounds. I’m taking Phentermine again because I noticed that when I went off of it, it didn’t take much to gain it all back. This time around very first day I took it I took my 30 milligrams and I felt burst of energy all of a sudden within the hour of taking it. A couple days into taking 30 milligrams of Phentermine I noticed I started to feel dizzy shaky and nauseous. I didn’t feel this the very first time I took Phentermine but I was also a little younger. I’m 29 now I was 21 then. Although on Phentermine then I did not eat like I was supposed to. I didn’t have an appetite. I also did not drink water as much because honestly I don’t like water. I also did not exercise, just my daily routine. Now with this time around I ate something a tortilla shell with cheese on it warmed up in the microwave and I drank a full bottle of water all within an hour and my nausea, and dizziness is going away. I also forgot to mention that I felt a little weak. I do have dry mouth but drinking water and continuing water I do believe will take care of that, I will note that later on. I found that when I go to bed at night I sleep for hours and get up with the baby and then I’m wanting to stay awake. With feeling the way that I have been feeling I have not had much energy. But I’m sure that now that I’m drinking water and going to be following the eating guidelines I’m sure I’ll have more energy. I’m 5 foot 5 and 173 pounds. I just started taking this a week ago.

  74. I am on the 15.5 dose and I have lost ten pounds in two weeks with strict weight watchers commitment. I am finding I have terrible terrible gas. I have tried gas pills and they do not even touch the problem. I am having a smoothie within the day so I am going to the bathroom regularly but I need a suggestion or I can’t continue this path that seems to be working for me. I see many other posts with no viable suggestions.

    • Hi Mia,
      We’ve had a lot of people telling us about problems with constipation on phentermine but gas hasn’t been something anyone has asked about until now. Gas isn’t a listed side effect of phentermine so if it is causing this effect for you then it might be related to your diet or eating habits. This article explains how to reduce gas and bloating: https://www.phentermine.com/blog/bloating-lose-weight-phentermine/, including which foods to limit or avoid, as well as tips such as eating slower and chewing thoroughly.
      Sally, phentermine.com

  75. I start taking it in the morning. Any suggestions? Take with or without food? So afraid after reading all of this.

    • Hi Stephanie,
      You should follow the instructions given to you by your doctor about when to take your phentermine. If you weren’t given any instructions then ask your doctor as soon as possible. In the mean time, most people are advised to take their phentermine first thing in the morning on an empty stomach around an hour before eating.
      Sally, phentermine.com

  76. Started this morning with half a pill. A little bit light headed and feeling sick to my stomach. No shakes though. Just the sweats. Any suggestions would be greatly appreciated.

  77. I take this medication an hour before I eat anything and haven’t really been hungry. But this morning I woke up with the shakes. Also usually by 11am I am drained and ready for a nap. I am drinking 180 ounces of water a day. My doctor said 1000 calories a day which is way hard to do. I am afraid to take another half of this medication at 11am in fear that I will be up all night.

  78. Not feeling so well today. Does anyone know if there is a lower milligram than 37.5

    • Hi Stephanie,
      Yes – phentermine is available in a variety of dosages: 8mg (Lomaira: https://www.phentermine.com/blog/lomaira-new-phentermine-drug/), 15mg, 30mg and 37.5mg. This article explains about the different dosages and what determines which you’re prescribed and how different dosages are better for different people: https://www.phentermine.com/blog/phentermine-dosage-guide/. If you’re taking the phentermine tablets then you could try splitting the pill in half, but if you’re taking capsules then you will need to speak to your doctor about prescribing you a lower dosage.
      Sally, phentermine.com

  79. My doctor has me on 1000 calorie diet with this pill which is so hard to do. Any suggestions on how to do that or what foods?

  80. Was reading some other articles on this medication. Does it actually cause heart problems and heart disease?

  81. Female 28yrs 235lbs 5’4″ (2 kids, 40 hr job ( medical office) with soda and sweets cravings
    Phentermine Phentermine… Phentermine.
    Firstly, great blog, I really enjoyed reading this info it was very motivating and informative. I’ve been on this medication for about 3-4 days, now 37.5 mg was advised to be taken 30 mins prior to meal once daily. I am a certified medical assistant in an allergy office, and naturally self assertive when it comes to medications I ingest. I literally read about this medication for a month prior to filling my rx which was not covered by my insurance. (Try blink.com by the way… I paid $6.95 for a $35 monthly rx)
    Futhermore I opted to start on 1 of my pills that night 5 pm and could not sleep that night. With the overwhelming excitment of filling the rx, and the med effects… I was on cloud 9. Heart pounding and happy!!!! I cleaned the whole damn house that night… Top to bottom and mopped (I’m sure have undignosed OCD as well lol) I knew to increase my water intake… Which I hate. I’ve never been a water drinker. Sadly I’d drink about a 2 liter of my favorite mountain dew a day. (I know don’t judge me) I’m not sure if it’s the medication or my drive… But Just the thought of something I should not have causes a tense feeling in my abdomen… I now know it’s the neurotransmitters. I took 1/2 the next day at about 11:00 am… I’ve never been a breakfast eater so I wasn’t hungry, because I was full of water from feeling dry mouthed all night. This day I also downloaded the app “lose it” to monitor my calorie intake as I noticed that day and the night previous my appetite was immediately curbed and almost stalled. This day effects I had were an overwhelming amount of energy and even increased sexual desire with my partner.( I just wanted to release some energy with him Lol that’s exercise right) Mind you… I’m 28 and have never been big on sex however that may sound… But I just always felt blah towards it, I’d rather cuddle til we fall alseep. (I have an amazing boyfriend by the way… He puts up with all my crap) that was a definitive plus… ✔.
    The next dosage I took a whole tablet 37.5mg the following day with the same effects: excitement, increased heartrate (to be expected), fullness, increased sexual desire, and overwhelming energy therefore, we… My family: bf and two kids went to the park and walked a trail. Out of breath I was determined to make “lose it” (the app) proud and log my exercise for the day…. After the trail I was tired… But could not sit and watch my girls play while I feen for a gulp of mountain dew, like I’d normally do… I wanted to keep walking… So jogged up and down a few stairs on the play field bleachers to keep me busy. I’ve never been this determined I thought!!!
    I say all that to say. This medication I think helps you to get on the right track of a mind change for weight loss. While I know tolerance to the medication can occur I will continue to alternate between a full and half dosage. And I will just do my best while on the medication in order to reap its full potential as I learn that good old fashioned exercise and dieting is alternatively the key.
    I’m unsure of any weight loss yet… As I ONLY like to weigh in weekly, I’ll be sure to provide an update.
    I’m eager to see how drinking water, avoiding and feeling repulsed with fullness at the thought of waffle house’s all star (a know fav of mine) for a grilled chicken salad and or noodle company soup (my kids and bf are not dieting lol), increased sex drive and no urge for soda… But WATER!! Has done for me
    Happy shedding to you all.
    Perhaps starting with half of the medication, planned light meals, and exercise may help those with insomnia and/or overwhelming energy and medication side effects. Counter attack them essentially by giving in to the effects of the medication in order to reduce the side effects.

  82. I have been taking Phentermine for 2 1/2 days… no symptoms, at all, until after lunch on my 3rd day. I was in the
    Mall walking at a normal pace to my car & I began to feel
    VERY hot & sweaty, which is not a normal occurrence for
    me, as I don\’t sweat a lot, even when I work out. I went
    back to my office & the sweating stopped, but my face
    felt red & flush the rest of the day, through the night & now I
    am awake, since 4:30 am…& it still feels flush. I had a dull headache as well, last night but that subsided with 2 Tylenol.
    Is hot, flush face a normal side-effect? I am not having
    chest pains or any other issues. I can\’t cut the pill in 1/2
    because the Dr gave me capsules. Nervous to take the next dose without knowing if this side-effect I am experiencing is \’normal\’.

  83. I have been taking phen for 1 week and have insomnia real bad. I take it at 5am and still by the end of the night I\’m still wide awake I eat regular low cal food oatmeal for breakfast, salad for lunch, steamed kale with brown rice and avocado for dinner so my eating is not the problem. Do any one of you have this problem if so please help me!

  84. Hello I have been on phentermine since February and on may 7th I had 3 grand mal seizure\’ s on that one day and was told that it was caused buy the phentermine. I have stopped taking it, have a lot of other women had this happen, and how often have they experienced another seizure. I was told I can\’t drive for six months and wasn\’t put on any anti seizure meds

  85. I have been on for a little over a week 37.5mg take once per day. I recently (yesterday) started experiencing swelling in my feet and ankles. I also just recently returned from a week long trip to Disney with LOTS of walking. Is the swelling due to vacation or the meds?? What can you do to avoid if it is due to the pills?

    • Hi Heather! It could be either, but regardless check with your doctor about this issue ASAP. It could be the travel or it could be the sign of a more serious side effect, or anything in-between. For more information about phentermine side effects, please visit https://www.phentermine.com/phentermine-side-effects.htm.
      Best regards,
      Rachel, phentermine.com

  86. I\’m on my third day of taking 37.5 mg\’s. Maybe I missed any suggestions regarding the bad taste you get from Phentermine, but I\’m wondering if this abates, or at least gets better the longer you take the pill? I\’ve also had some horrifying diarrhea that has made me nervous to take this for fear of an accident at work…will this too get better over time?

  87. I started taking the Phen..I have noticed that when I have to go pee….it takes a few seconds to get started…I did not have this problem before….has anybody else had this problem…

    • Yea, me too. Also feel like I can\’t empty my bladder.

  88. I started phen 7 days ago. It gives me bad anxiety and heart palpitations. Makes me feel like I\’m constantly driving fast over hills (ya know that feeling!) Should I consult my dr or just stop taking them? An EKG was not done before I started taking them.

    • Hi Davis. We would recommend speaking with a doctor about these side effects immediately. Give your PCP (and/or prescribing doctor) a call and tell them what’s happening. Even if you can’t get in for an appointment today, he/she would be best able to advise you on how to proceed. In the meantime, you may also be interested in this page about the side effects of phentermine: https://www.phentermine.com/phentermine-side-effects.htm.
      Rachel, phentermine.com

  89. I have been taking phentermine 37.5 for a couple of weeks now. I have been experiencing dizziness and I know that is common and to drink lots of water. But there is another side effect that has been happening that is very bothering. I have been having facial tingling in the cheeks. They are very sensitive. If I work out or get hot and flustered it will flair up worse and get really hot and more tingly. I don\’t know if it is the pill or something else. Is this normal?

    • I think it\’s the pill… I have been on Phentermine for a couple of weeks and along with the usual side affects I have noticed that I am extremely sensitive to the sunlight. I\’m talking walking to the car sensitivity! My skin tingled at first, but now it stings. I am very pale naturally and burn easily, however this burning is very different. It started on the top of my shoulders and slight down because I had my back turned on the sun for too long. Now on my neck and chest and my face and arms. Pretty much wear clothing is not protecting my skin.. It took a while for me to figure out it was from the sun, so I was out unprotected. It doesn\’t look like a sunburn either it just stings. Now heat and sweat both affect those areas. I\’ve also noticed that my skin has a different texture there too, almost scaley if you will, and turns slightly red or pink if over heated. I have had to stop wear moisturizers in those places because if I do sweat or get hot it agitates it more. The only relief I can find is aloe vera. In the mornings and evenings if I\’m not already showering, I wash with cool water pat dry and apply the aloe and a very light moisturizer on my face. The relief is instant since aloe has that cooling affect, and the scaley texture is lessening. I\’m just using off brand \”sunburn\” aloe at the moment because that\’s what I have on hand, but plan on purchasing as pure as possible aloe, or aloe and propolis, as the benefits are awsome.. I am going to try sunblock, I usually cant wear it because it makes my skin oily and break out, but maybe it won\’t now.
      The phentermine has made my skin so dry, I don\’t know if thats what is causing the sensitivity or maybe it is just the Phen. What I do know is that there are others that are having the same issues with sensitive skin from the Phen, but there is very little info. I have been searching for over a week finding only the question and zero feedback… Its trial and error atm since some products relieve and others agitate, well for me anyway.. I have cut back on the phen taking just half of a 37.5 to see if that will help get it under control.. I hope this helps.

  90. I have been taking 37.5 for two days now but today I threw up more than 7 times and I\’m still very sick right now. Should I stop taking these pills? I take them at 5 or 6 in the morning….

    • Hi Candise! We would recommend speaking with your doctor about this ASAP. A little nausea and/or upset stomach is common side effect when starting phentermine, but persistent or severe nausea and vomiting is always something you should go to the doctor about. Hope you feel better soon!
      Rachel, phentermine.com

  91. I\’ve been on phentermine for a month now but now I can\’t urinate fully or pass bowel movements should I be concerned. My pill is at 37.5 one pill a day

    • Hi John, thanks for your comment! We would recommend contacting your prescribing doctor about these side effects. It’s normal to experience constipation on phentermine, and men on phentermine frequently report trouble passing urine. However, given that you’ve been taking the medication for a about month now and are still experiencing these unwelcome side effects, we would suggest speaking with your doctor. He or she is the best person to help you work through these problems safely and efficiently.
      Rachel, phentermine.com

  92. I started taking 30mg yesterday, after it was in my system for about 6 hours my hands starting burning. Again today the same thing. Is this considered a serious side effect? Will it go away after a few days or do I need to stop taking it?

    • Hi Sue! We don’t often hear about phentermine users experiencing burning hands, so we would recommend speaking with a doctor about your reaction ASAP. He or she will be best able to assess the cause of this side effect and determine the best course of action.
      Rachel, phentermine.com

  93. Hello, started taking half a 37.5 pill on Oct 5th. It seems to be working well but my lips/ mouth is numb from time to time. It\’s very odd and annoying. Questioning if this will go away after awhile.

    • Hi Bird! If you’re still struggling with this numbness in your lips/mouth, we would suggest speaking to your prescribing doctor ASAP. Dry mouth and lips are a very common side effect, but we don’t hear usually hear this described as numbness. So, we’d recommend speaking with your doctor since he or she would be best able to determine what’s causing this reaction and hopefully help you resolve it!
      Rachel, phentermine.com

  94. Hello, I have started taking 37.5 pill in the morning daily. Everything is fine until later in the day then I get nauseated, shaky, diarreah, just sick feeling all around. Why do you think this only happens later on in the day? If it was side effects I would think it would start after taking it not toward the late afternoon. I didn\’t know if maybe it was some sort of withdrawl from it wearing off but I don\’t know. Any help is greatly appriciated!

  95. Hi, I took one half tablet of 37.5mg yesterday around 2pm it\’s been exactly 24 hours aND the gitters are just wearing off. I\’m nervous to take another because I don\’t want to feel gitters fir 24 hours. Any advice? I drank plenty of water but only was able to eat one full meal.

    • Hi Latrice! If the jitters and extreme appetite suppression continue, you could consider speaking with your doctor about a lower dose of phentermine. The effects of phentermine are often strongest when you first start the medication, but it’s important that you can still sleep and eat at least about 1200 calories per day. So, if the reaction remains strong, it may be a good idea to speak to your doctor about adjusting your dose. Never adjust your dose without speaking to your doctor first.
      Rachel, phentermine.com

  96. I have been taking phentermine every other day with food instead of on an empty stomach and still experiencing great results. I eat healthy and drink lots of water. Does anyone else use this drug this way?

  97. I have been taking Phen for 7 weeks and worked through the majority of side effects (i.e.,sweating, dry mouth. bloating and nausea), Developed urinary difficulties, going frequently day and night, urgency, feeling could not empty bladder, slow urinary flow. This seemed to subside after a few weeks, but recently have returned, along with constipation that I had. Good news is I have lost around 20 lbs. Any advice, or are others having similar issues?

    • Hi Greg!

      What you describe are pretty common side effects of the phentermine treatment. Have you browsed our official Facebook support group?

      For constipation, we have some suggestions and tips on how to combat it in this blog entry.



  98. I am in Australia and Phentermine here comes as a capsule rather than tablet. I took my first 30mg capsule this morning and I feel very spaced out and I am having waves of anxiety and it is a very scary feeling. I can\’t wait for it to wear off.

    Is there a safe way to halve a capsule with all the little beads inside so I am only taking 15mg? It\’s costs $115 for a months supply so I really don\’t want waste the money because the 30mg are too strong.

    Does the weird anxious feeling subside as the days go by or should I reduce the dose?

    • Hi Hannie!

      We definitely DO NOT recommend splitting a capsule. There is no way to create equally measured halves with capsules, so our recommendation is consulting with your prescribing doctor immediately, because there’s other options he/she could suggest.



  99. This is my 3rd day on phentermine. The first day was fine. Second day I felt dizzy, sick like I needed to vomit, and had no appetite what so ever. Today I decided to take half. I ate 45 mins after, but before I ate though I vomited. I’m feeling very nauseous right now. Makes my stomach feel weird. I have went from 213lbs to 206lbs in just 3 days. What can I do to help myself get through this everyday. I feel so sickly.

    • Dear Chelsea,

      If you are feeling sick or uncomfortable with the phentermine side effects, we urge you to contact your prescribing doctor as soon as possible. The dosage might be too much, or he could provide you with additional and important insight.



  100. I’m on my 3rd day of taking 35.7 mg of phentermine. I’m 227lbs. I started going to the gym at least 4 days a week for 1hr each time before starting phentermine. When I started taking the pill I noticed a high increase in energy, very slight dizziness but my heart races fast through out the day even when laying down but no pain really.Will this symptom wear off? Or why does it do this? My doctor checked my blood pressure the day she prescribed it and said it was really good. My first day of taking the pill I slept 2hrs but on the 2nd day I slept 6hrs. I’m also having a sour taste in my mouth aside from dryness what is this due to?

    • Hi Elena,

      The symptoms you describe are common with phentermine. This drug can affect your heart rate and blood pressure. These side effects tend to diminish with use, as your body creates resistance to phentermine.
      The sour taste in your mouth is a typical example of xerostomia (dry mouth) symptoms; the lack of saliva makes it easier for topical bacteria to thrive, and therefore, you might feel a sour taste in your mouth, or bad breath.



  101. Hello
    I am on my third month of 40mg. It is possible the effect is wearing off as my body builds a tolerance. Yesterday I woke sooooooo dizzy and sick. Today approximately 40% of those symptoms. I am pushing fluids and also I noticed the last 3 days I can\’t stop burping.
    Could this be a side effect of some kind of virus? I have not been sleeping well the last 8 days due to starting a new job and my mind is in overdrive…
    Also the Dr said he will only give 3 months as usually it is not as effective. Can I use the medication again after how long as a short term weightloss plan?
    Also when stopping 40mg should I slowly decrease dose? Because I. Tried to skip it 2 days when we had a busy food weekend and coincidentally I had a tension headache those days.

    • Hi Nivedita! Yes, it is common to develop a tolerance to phentermine – especially towards the end of your prescription. This is one of the many reasons that it’s only recommended to take this medication for 3 months at a time. It’s possible to take multiple rounds of phentermine (with about 1-2 months break in-between), but your doctor is the only one that can determine if this is right for you. You may be interested in our article about why you need to take a break from phentermine.

      Regarding your question about weening yourself off phentermine, yes – some people do better if they come off phentermine a little slower. Still, you should never adjust your dosage without first speaking to your doctor. If you discuss your concerns about withdrawal symptoms with him or her, you two can set-up a plan together. In the meantime, you may like our article about how to avoid withdrawals with phentermine.

      Finally, your symptoms could be either a virus or the phentermine. If you continue feeling bad, or your symptoms get worse, we would suggest contacting to your doctor. You don’t want anything getting in the way of your new job 🙂

      Hope you feel better soon!
      Rachel, phentermine.com

  102. My first with it I had a lot of energy also the next day I had it, then 5 days pass and I started to got a very slight dizziness but yesterday I got 3 times dizzy yasterday I started to fell my heart races fast when laying down but no pain, when doing small things.

    • Hi Ana! We would recommend speaking to your doctor about these symptoms. Dizziness and racing heart are both common side effects of phentermine, but if these symptoms are interfering with your everyday life, not going away or getting worse, you should bring them up to your doctor. Hope you feel better soon!
      Rachel, phentermine.com

  103. I started taking phentermine last year and loved the steady energy it gave me and the weight loss, but after after a month of taking it I noticed that randomly one day it felt like my throat was swelling and felt a little hard to breathe, the anxiety about it probably didn’t help either. This continued for a couple more days and I would start to feel it within a couple hours of taking my pill in the morning. I stopped taking them and haven’t had this experience since, but I’m not sure if I can 100% blame the phentermine for those symptoms or if it was just a coincidence. I’d really love to start taking them again but I want to be safe.

    • Hi srolfe, thanks for your comment! We would suggest discussing these reactions and concerns with your prescribing doctor. Throat swelling and trouble breathing are both serious reactions, so if it is the phentermine that’s causing them you wouldn’t want to re-introduce the medication into your system. For this reason, we suggest sharing your past experience with your doctor when you talk about phentermine again to see what he or she would advise.
      Rachel, phentermine.com

  104. This is my 2nd time taking Phentermine, never have i had an issue with it, but i been experiencing itching at night and only on my arms and mainly more on my right arm. I dont know if getting diagnosed with gallstones has to do anything wit the itch but it’s becoming unbearable! I also sometimes don’t drink as much water as i should,i Never had this symptom before.. any help or suggestions?

    • Hi Kika! We’d suggest chatting with your doctor about this new reaction, especially if it’s not going away or it’s getting worse. Hope you feel better soon!
      Rachel, phentermine.com

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