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Phentermine is known to be an extremely effective weight loss medication. However, for those taking phentermine, the effects and results can vary throughout their prescription, and many of our forum users report that they feel their phentermine has stopped working, sometimes just a week or two after first starting to take it. Here we examine how phentermine works, what can cause a reduction in its effects, and how to overcome these issues in order to achieve great phentermine results.

How Phentermine Works

Phentermine acts on the central nervous system to stimulate the release of neurotransmitters in our brain, including dopamine, epinephrine (adrenalin) and norepinephrine (noradrenalin). This causes phentermine to increase alertness and energy levels, reduce hunger and minimize cravings. By helping to suppress appetite, phentermine encourages you to establish a healthier diet; with reduced cravings and less hunger, you will be able to concentrate on eating better and learning how to feel full while eating fewer calories by loading up on protein, fiber and lots of fruit and veg. Additionally, with the extra energy that phentermine gives due to its stimulant properties, you’ll feel more motivated and better able to begin exercising, establishing a daily routine of activity to continue in the long term.

Phentermine Weight Loss Stages

If your hunger has started to come back or your energy levels have started to dip, your first instinct may be to wonder, has phentermine stopped working for me? However, phentermine effects, and the subsequent phentermine weight loss, come in stages, so it is perfectly normal to experience a reduction in phentermine effects and smaller losses. This is because the sustained use of many drugs causes adaptation within the body that tend to lessen the drug’s original effects over time, known as drug tolerance. Many phentermine users experience a reduction in effectiveness of the medication over time, which indicates that tolerance is occurring within the body. This is often the case for those who have taken phentermine in the past when they return to taking it again.

When you first start taking phentermine, as well as the negative side effects, you’ll also feel the desired effects of appetite suppression and additional energy at their most powerful. Therefore, it’s possible that you could see some big losses during this period, partly due to losing water weight and partly because your motivation and energy levels will be at their highest. However, after the first few weeks, whether or not you experienced some big losses at the start, these drops are not sustainable in the long term. Your body can only physically shed around 1-2 pounds of fat per week, so it’s likely that your losses will begin to reach a steadier rate in this second stage. If you’re losing weight while toning up and building muscle, this is a positive step as steady weight loss ensures that you’re losing fat and gaining lean muscle as a means to achieving and maintaining your weight loss goals for life.

Has Your Phentermine Stopped Working?

You may think that phentermine has stopped working for you if you feel your hunger returning, however the appetite-suppressing effects of phentermine will change over time; perhaps at first you had to force yourself to eat, as many of our forum users have reported, but these extreme effects will only last for a few days if you experience them at all. While it may seem that struggling to eat anything is a good thing if you’re trying to lose weight, as with most things in life, balance is essential when it comes to appetite, and neither too much nor too little is a good thing. With no appetite, you will be unable to eat enough to keep your metabolism running at a fast enough rate, and without the fuel it needs, your body will slow down, meaning that any food you do eat will not be turned into energy as efficiently by your body, resulting in slower weight loss.

Even if you do manage to successfully lose weight on phentermine while eating very little, when your prescription comes to an end you will regain your appetite and, without having learned healthy eating habits, you are most likely to regain the weight you lost as well, as reported by this forum user. Therefore, a reduction in the extreme appetite suppression you felt at first is actually a positive thing and doesn’t indicate that your phentermine has stopped working. Remember that phentermine isn’t a miracle pill, it is just a kick-start to get you on the right track, and so you should treat your phentermine prescription as your opportunity to benefit from decreased hunger and increased energy to learn how to establish healthy habits for when your phentermine prescription comes to an end. A good way to put things into perspective is to think back to what you used to eat and what you’re eating now, and imagine how hungry you would be without phentermine on a low calorie diet, as this forum user explains. If you think that phentermine has stopped working, you may just have forgotten how strong your appetite used to be.

If you’re more concerned about your losses slowing down, then you should remember that the scale doesn’t always tell the whole truth; the scale doesn’t show the inches you’re losing and the new shape you’re working towards, nor that you’ve reduced your body fat ratio and built muscle this week. For this reason, old photos, old ‘fat’ clothes and a tape measure are your best weight loss weapons to remind yourself how great you’re doing. And, you should always keep in mind that the feeling of finally fitting into that pair of skinny jeans you’ve had in your wardrobe for years will be a million times better than seeing a number on a scale!

phentermine stopped working

How To Boost Phentermine Effects

Drinking plenty of water, regular exercise and eating the right foods will help to boost the effectiveness of your phentermine prescription, plus aiming for an alkaline pH also ensures that phentermine remains in your system for longer, therefore offering you stronger and longer-lasting effects, as explained here. This phentermine weight loss schedule also offers lots of great advice on how to make sure your phentermine prescription is continuously working for you throughout the day, and these tips will help you overcome a weight loss plateau if your weight loss stalls.

If you think that your phentermine has stopped working because you’re not feeling the energy boost you did at the start, this can also be due in part to the natural reduction in phentermine effects that occurs over time as your body becomes more used to the medication. However, if you’re lacking in energy or more fatigued than before, this could be as a result of the phentermine side effect of insomnia, or could be due to an energy dip following a period of over-stimulation. However, adverse effects of phentermine also include drowsiness, fatigue, and reduced energy levels, as discussed on the forum here and here, which can occur alongside or instead of symptoms such as insomnia. These reactions, whereby a stimulant such as phentermine causes fatigue and sleepiness without an energy boost are called paradoxical reactions, and are more common than many realize. This fatigue could be a passing side effect, or may be as a result of an undiagnosed medical condition such as diabetes, thyroid problems or PCOS. It could, however, be something as simple as a vitamin deficiency; for example, low levels of magnesium can cause tiredness, as can insufficient levels of vitamin C. To counteract these problems with fatigue while also ensuring that you are getting the right amount of crucial nutrients, and simultaneously giving yourself a great weight-loss boost, we recommend that you take Phen Vites, the only multivitamin especially designed to help those taking phentermine. This multivitamin complex contains a multitude of essential vitamins and minerals for good health and more effective weight loss, as well as nutrients specifically prescribed to phentermine users to boost their loses, such as 5-HTP and vitamin B12.

We also recommend adding the weight loss supplement Phen Caps to boost the effectiveness of your phentermine prescription by offering additional appetite suppression and an extra energy boost. This leading phentermine alternative uses a combination of different active ingredients to provide your body with a different source for these effects when your body becomes accustomed to phentermine. It is important to always follow the instructions of your doctor, so if you find that your phentermine prescription does not produce the same effects, you should not increase your dosage in an attempt to manage your increase in tolerance. Doing this will only lead to a greater dependency and therefore a greater chance of withdrawal symptoms, including weight gain, once your prescription ends.

Do you think that phentermine has stopped working for you? Or do you have any advice for how to overcome the reduction in phentermine effects? Let us know by commenting below.

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80 Responses

  1. I’m taking phentermine for almost three months
    Now and I’m not loosing any thing and I m
    Noticing that I having chest pain also I don’t know. What’s wrong now I’m scared . But my
    Friends r taking and it works very good for
    Them . Can u suggest me what to do plz

    • Hi Anisha,
      Chest pain is a serious side effect and one that you should tell your doctor about immediately. Everyone is different so this is why your friends might not have the same problems as you, but you definitely should tell your doctor about the chest pains as phentermine just may not be suitable for you.
      Sally, phentermine.com

  2. I have been taking phentermine knowing the side effects such as, chest pain, weird taste in mouth, heart beat increases sometimes, but i have lost more than 20 kilos in 2 months following the doctors instructions, so i think its more positive than negative to me.

  3. I started Phentermine 37.5 in late April 2014 … to date I have lost 74 lbs…. I turned 57 in Dec 2014. I was always thin, (5\’5 128-135 on a bad day) until Menopause at about 51 is when I started to gain steadily. At 56 I had gained a total of 95 lbs between 51-56. I was starving all the time, craving sugar, craving food I never really ate before and weird cravings that made zero sense to have. I thought for sure my Thyroid stopped working due to the Menopause so I finally went to an Endocrinologist. All my tests came back fine … I was definitely in Menopause was all that the tests confirmed. I was put on Adipex 37.5 which is Phentermine and immediately my appetite went back to what it used to be… no cravings for sugar, no huge appetite, preferred clean foods over heavy, carbed foods. I am now nearly 1 yr into this … unbelievable but true that the Phentermine doesnt work like it used to however … it still staves off the appetite to where I can control the \”impulse\” to eat something bad for me. I have been off ALL sugars, including fruits, ALL carbs with the exception of Lettuces and the occasional 1/2 low carb pita pocket once or twice a week. I eat mostly Proteins … lots of chicken breast meat, fish, steak, egg whites, salads. I eat healthy and clean and I everything in me and on me has improved 100%. I no longer have Acid Reflux disease, I no longer have IBS, I sleep better and no longer snore or wake up gasping for air, I can walk and stand like I used to without my lower back muscles twisting up, I can breathe better then ever. I didnt expect Phentermine to work like it has OR as long … but I still have 22 lbs to go to be back to my 128 … and then it is maintain…. that will be the hard part. I am having the cravings sneek thru BUT … I know I have to remain focused and always keep the healthy stuff at the ready … I can not be without a boiled egg or cherry tomatoes to get me thru to the next meal. I still get full quickly and that is a plus. I have a choice … I have to focus when I need to and make the right choices. Ive been to parties and I still make the right choices … there is always a veggie plate or a plain meat or salad … no worries … I love Proteins, not everyone does … this works and I am forever grateful to my wonderful Dr and Phentermine for keeping at bay the hunger monster… lol

    • You are definitely dead on the money! Your story sounds like mine….it helps with my monster cravings too;) LOL

      I’m a protein freak! Shakes, chicken, fish and definitely veggies and let’s not forget my boiled eggs!

  4. Ok so I\’m about 45 days in and I feel like my head is tingly. Just wondering if that could be from the pill? The first 30 days I wasn\’t hungry, but the last 15 days I think it\’s just not as affective! Im trying to stay positive.

  5. I have been taking phentermine for a month. Besides obesity, I have many other health problems. I have hashimotos hypothyroidism, polycystic kidney disease, and a few other moderate issues. I\’m taking 200 mcg of thyroid hormone so that is regulated. I\’m also anemic and vitamin D deficient. Since I have high blood pressure because of impaired kidneys, my doctor started me on 15mg of phentermine. That put me to sleep and drained what little energy I have. So it was doubled to 30mg with a promise I would monitor my bp. I did several bp checks a day. The phentermine did absolutely nothing to me. I actually am not a big eater, but I\’m a grazer. I also exercise a lot. Im the fattest person running a 5k. Im slow but I always finish. I\’m prediabetic because of impaired kidneys and poor diet so I\’m on a very low dose of metformin. So I will finish my last dose of phentermine tomorrow. I\’m just wondering if there is anyone with so many other issues that phentermine did nothing for? Is it worth trying another round of phentermine?

  6. Phentermine has worked wonderfully for me. I\’ve lost 40 lb. but still have 10 to go to reach my goal. It has definitely stop working, so I know my body has adapted to it. MY QUESTION: How long does one need to remain OFF phentermine, so resuming will result in appetite suppression and weight tloss once again? Thanks for any info!

    • Hi Carrie,
      Generally doctors will make patients take a one month break after three months of taking phentermine. However, phentermine is designed to help obese patients establish healthy lifestyles, meaning a lot of people will stop phentermine before reaching their final goal. Because of this, a doctor probably wouldn’t prescribe phentermine to someone needing to lose 10 lbs. The break is also intended to see how well the patient does without the help of phentermine, so perhaps this could be a good test for you to see if you can maintain or lose weight without the help of phentermine.
      Sally, phentermine.com

  7. So this has been my experience with phentermine. I started out taking just 15mg. No change in anything. I doubled it to 30mg on week 2. I did end up losing 10 pounds in the first month but have since stalled. Now I take 37.5mg every morning. My weight fluctuates between 10-12 pounds. I have never felt ANY heart palpitations, no jittery feelings, no having to make myself eat!! I absolutely feel no difference no matter what dose I take! I feel like it\’s not working for me like it has others. My friend says she is never hungry! I\’m always hungry! Wondering if I can take 2 37.5mg?

    • Hey Lori,

      It’s not unheard of for people to take more than 37.5mg per day but it’s not usually recommended either. We would advise you to speak to your doctor, as rather than a higher dosage, it might be better for you to switch to a different medication.
      Sally, phentermine.com

    • You know lori I feel the same I guess it’s not for me either i still be hungry myself also be feeling nausea

  8. Hi do we have to wait to eat 45 mnt after we take this pill. Or can I take the pill and eat at the same time?.

    • Hey,
      Your doctor should have explained when to take phentermine and when to eat, but usually you’re meant to take it and then wait about an hour before eating breakfast. If you’re not sure then it’s best to ask your doctor.
      Sally, phentermine.com

  9. hello, a cpl years ago I started taking phen and I lost 30 lbs from the prescription my doctor gave me, she gave it to me for 3 months then I had to take a 6 month break. before the 6 months were up my doctors office closed which forced me to find a new doctor, my current doctor will not prescribe any diet pills so I went to a diet clinic and got the medicine there. this is my 3rd day on it and I feel absolutely nothing, no energy and im still hungry. im not a big eater but I do eat the wrong things at the wrong times, ive recently changed my eating habits and I am drinking more water but I still havnt seen any results. I know 3 days is kind of early to decide if its working or not but im afraid its not going to work this time, my question is, even if I don\’t have any side effects does it still work? and also does phen burn fat? thank you.

    • Hey Renee,
      Phentermine doesn’t burn fat, it just helps you to be more active to burn more fat, so if it’s not helping you to eat better or giving you more energy then it’s not doing anything for you that you couldn’t do yourself. I would wait a few more days and see if you see any results or start to feel different and if not, then maybe speak to your clinic and see if they can help you with a different prescription or dosage.
      Sally, phentermine.com

  10. I took Qsymia for about 4 months and lost 35 lbs. It worked so well for me that it even took away my cravings for sweets. I maintained the weight loss for about 10 months, working out several times per week. I felt so good about myself. Then some traumatic issues happened in my life that put me into depression. I’ve gained 25 lbs back and lost interest in exercising. I’m trying to get back on track. I went back on Qsymia but it has absolutely no effect on me. Is there anything I can do to get it to work again? Thanks

    • Hi Donna,
      We published an article more recently which gives the top ten reasons why people might not be losing weight on phentermine. Here is a link: http://www.phentermine.com/blog/why-not-losing-weight-with-phentermine/ However, it sounds like the Qsymia is no longer working for you if it has no effect on you, so without the support of Qsymia it’s you doing all the work, which you could do without medication. I would speak to your doctor about trying something else in terms of weight loss medications, or perhaps adding a supplement like Phen Caps to see if the different ingredients and mechanisms can help to kick start the effects. In addition, it would be advisable to seek counselling or speak to someone about your depression, as without resolving this issue then emotional eating and lack of desire to exercise may continue to halt your progress with weight loss.
      Best of luck!
      Sally, phentermine.com

  11. Here’s another reason why phentermine is not working: BECAUSE THEY HAVE ADDED MORE FILLERS AND LESS ACTIVE INGREDIENTS! It’s clearly not the same as it was 15-20 years ago and I’m talking about after they removed the “fen” from it! Adderall, which is often prescribed to little children (!) is closer to the strength of the original phentermine. Obviously, they just want to make $$$ but they don’t want anyone to become thin and healthy otherwise they (Big Pharma) wil lose their Cash Cow, pun intended. Evidently, all these people who are “losing 75 lbs” and “full of energy” are PAID SHILLS for Big Pharma. I’ve gotten phentermine at every pharmacy in my area in the past year trying to lose weight since the bogus FDA took away ephedra, and it goes from weak to weaker to weakest at every successive attempt and every different manufacturer so far: Teva sucks. Qualitest barely works, KVK tech sucks, Mutual barely noticeable. They are obviously doing this on purpose then they try to tell you “your body has developed a tolerance to amphetimines”. Um, no it hasn’t! My friend has a prescription for Adderall and gave me one to try. IT IS STRONG ENOUGH FOR A FRIKKIN HORSE, yet this “phentermine” is barely more than a sugar pill with fillers that still cause insomnia, yet give NO ENERGY and almost NO APPETITE SUPPRESSION and what little they do give is worn off by the evening which is the hardest time for me not to eat and if I take them later I’m up all night. That’s about the only thing this garbage still does is give you insomnia. I took phentermine 20 years ago and it was like the Adderall is now but smoother and less harsh and it lasted ALL DAY LONG. Yep, they are doing this on purpose those sneaky bazturds. That’s the TRUTH from a real person. Ok, shills your turn.

    • Bingo! Totally agree with everything you said.

    • Yup!! Took it 10 years ago for 3 months and lost 40lbs… Full of energy and a great suppressant. Tried it again in July 2015 and NOTHING happened. The FDA definitely did something to the pill.

  12. I started phentermine September 12 and it’s now December 22 I have lost 47 pounds. The pills have slowed down a whole lot I’m barely losing a pound a day. However my doctor prescribe me a booster (Qudexy)to go alone with the phentermine but they are racing my heart.

    • Hi Abena,
      Well done on the 47 pounds lost, that’s great! I think you’re expecting to lose weight too quickly though; weight loss doesn’t work like that. Losing a pound of fat a day just isn’t possible, the most the human body can shed in unwanted fat is around 2 lbs a week. If you’re experiencing side effects with the booster your doctor has prescribed then I would stop using them and just stick with phentermine – if you’re still experiencing appetite suppression and an energy boost then phentermine is still working for you. The weight loss will naturally slow down as you lose more, or may be more up and down in the future but every pound lost is a step in the right direction.
      Sally, phentermine.com

  13. I started Phentermine 12/15 and was given 37.5mg. I dropped 18 lbs and was eating so much healthier because I did not starve all day. I had put on 40lbs in less than two years prior to that. At my follow up, the doctor reduced me to 15mg. I have been on that a week, gained 3 lbs and am constantly hungry. What can I do to help with the hunger? I have read about the Phen cap boosters but they are more expensive than the Phentermine itself. Any information about the 15mg vs the 37.5? It feels like I am taking a placebo pill and am eating worse because of the hunger.

    • Hi Cassandra,
      It’s strange that your doctor put you on the maximum dosage and then reduced it – typically it is the other way round, where patients are given a lower dosage to start with which is then increased as the patient builds up some resistance and is better able to handle the side effects. I would speak to your doctor if I were you, to see if he or she could put you back on the 37.5mg dosage, since that was really working for you.
      Sally, phentermine.com

    • Hi Cassandra you know my doctor done me the same

  14. It worked wonderfully for me about 10 years ago, but I stopped taking it when I reached my goal. Since then I tried it again several times after gaining back weight, but got absolutely no results at all. I can’t tell that I’m taking anything at all! This was after staying off it for a year or more. I think my body just got used to it and wish I could find something else that was as effective as Phentermine WAS!

  15. I have only taken 4 doses of my Phentermine. The first day I felt a HUGE difference, I was full of energy and had great appetite suppression. The next 3 days I have felt nothing, I’m hungry and tired.

    • Hi Leah,
      Phentermine doesn’t usually wear off so quickly so my advice would be to give it time – you need to take steps to help phentermine work by eating the right foods, sleeping well, being active, and drinking plenty of water, so concentrate on those and you might find that the phentermine starts to kick in again. It could also be related to your monthly cycle, as hormones can effect phentermine and vice versa. Be patient and put the effort in and you should start to see results.
      Sally, phentermine.com

  16. I have took Phentermine back in 2011 to lose weight for my wedding and lost 30+ pounds. Worked great. I’ve had 2 more babies since then and gained all of the weight back so I decided to try it again the end of last month. I’ve lost 20 lbs, which is awesome but now I’m stuck. No weight loss at all. No weight gain either, thank God, but still, I’m working out, eating healthier, drinking nothing but water, and also get lipo shots, and I haven’t lost anymore weight at all. Why would I not be losing anymore weight?????

    • Hi Ebony,
      It’s quite common to experience a stall in your weight loss, even if you are doing everything right, but 20lbs so far is great, well done! The thing to remember is that phentermine helps you to lose weight by suppressing appetite and boosting your energy levels, so if you are still experiencing these effects then it is still working for you, and it seems by what you say about how you’re working out and eating right that it is still working, or if not, then you’ve made the transition into making these healthy habits part of your life and maybe don’t need phentermine any more. However, why aren’t you losing? Well, it could just be a stall which is effectively your body catching up with itself – it sounds like you’ve lost the 20lbs in quite a short amount of time if you only started at the end of December, so it’s quite normal for your body to slow down on the weight loss – just be patient and continue to eat right and exercise and you should see the scale start to drop again. To help things along, here are some pointers that could help you: http://www.phentermine.com/blog/why-not-losing-weight-with-phentermine/
      Sally, phentermine.com

  17. Hi, I started taking Phentermine in October. I finished 3 months at a clinic and then went to a different clinic to continue. I have noticed that I have just felt “off” lately. I have brain fog, cravings have returned and I am always tired. I realized that I started feeling this way once I was on the new set of pills. I looked and saw that they are different than the ones I was taking before. Do you think it is the pill or do you think I need to change to a new weight loss drug. I haven’t lost any weight in 10 days and that is really shocking. I loved the phentermine I was taking because I felt like I had the energy that I was always meant to have and haven’t. P.S. I also have PCOS.

    • Hi!
      Although almost all phentermine pills (including adipex and other brands) have the same active ingredient, the inactive ingredients can sometimes play a part in the effectiveness of one pill when compared to another. It’s likely that your new clinic are just using phentermine pills from a different manufacturer, however, the side effects that you’re experiencing now that you weren’t before would indicate that these new ones aren’t working as well for you. The lack of weight loss in 10 days isn’t that unusual as many people on phentermine experience stalls and plateaus, however the feeling ‘off’, lack of craving control and feeling tired show that switching back could be better for you. Is it possible for you to return to the other clinic? If not then we would recommend that you ask your new clinic if they are able to prescribe the other pills you were taking. Hope that helps!
      Sally, phentermine.com

  18. I started taking phentermine 12/16 to date ive lost 26 pounds. In the 1st couple weeks I didn’t eat much and walked 3 miles a day. Now since maybe a week ago im ok at work in the but once im home Im starving. I even bumped up to 2 37.5 a day and still feel the hunger at night. The phen caps are way to expensive are there any other supplements that I can use with phentermine? Any suggestions on any over the counter supplements I can take I still have 25 pounds to go and Im petrified I’ll gain back what I lost if I don’t do something soon.

    • Hi Chyna,
      It could be a good idea to look at what else you’re doing – for example, are you sleeping enough? Are you still exercising? Are you sure that you’re eating enough throughout the day, and that the food you’re eating is what you need to keep your hunger at bay? Making sure to drink lots of water and eat filling foods full of fiber and protein are great ways to stop feeling hungry. This article has some reasons why phentermine may not be working for you: http://www.phentermine.com/blog/why-not-losing-weight-with-phentermine/ and this article has tips on how to suppress your appetite on phentermine: http://www.phentermine.com/blog/10-tips-suppress-appetite-phentermine. Also, some people who are hungrier in the evening can find it more helpful to take their phentermine later in the day, as long as it doesn’t start interfering with their sleeping patterns. Or, you could try splitting your pill in half an take half in the morning and half around lunchtime to spread out the effects. As far as supplements go, Phen Caps are the closest we’ve found to phentermine, and they have a money back guarantee unlike many supplements you’ll find online or in stores, so if you do decide to take a supplement then we think these are the best. Hope all that helps!
      Sally, phentermine.com

  19. I’ve been on it for years. Haven’t lost sh*t: 🙁 and I’m on adderrall and for a long time was on metformin and levothyroxine too. Nothing. I want to cry.

  20. I started 37.5 mg of phentermine 2/25/16. The first day it worked very well. It wore off around 5 pm which is fine with me, I was able to eat a small supper and I was able to sleep that night. But today I feel like it’s not working at all. I’m hungry but my stomach isn’t rumbling but it’s enough to make me want to eat and my lower back hurts a little. Is this normal? (Day 2 of taking the medication)

    • Hi Erika,
      Phentermine isn’t meant to completely take away your hunger – you should and will get hungry but it should be a manageable level of hunger so that you’re able to eat small healthy meals and consume a good range of foods throughout the day. Remember to eat 1200 calories per day at the VERY least and try to eat filling foods with plenty of fiber and protein, and drink lots of water too. With respect to the lower back pain, this isn’t a side effect of phentermine but if it is troubling you then you could mention it to your doctor to see if he or she is concerned about it.
      Sally, phentermine.com

    • I’ve noticed with myself that if i feel hungry without my stomach rumbling then it is a craving or I am thirsty. In my experience, I am not truly hungry unless my stomach rumbles. Take it for what it’s worth but I do know that we often mistake thirst for hunger.

  21. I have been taking phentermine for a week now have lost 15lbs but the energy level was great at first now I feel like I just don’t want to do anything but I push myself to walk 30 min to an hour a day I only had headaches for about 5 days no side effects now I been drinking about a gallon of water a day and eating healthy foods managing about 800-1000 calories a day. Should I be feeling tired now????

    • Is it maybe cause I’m not eating enough???

  22. I have been taking phentermine for 12 months straight. I lost 50 lbs and then maintained until 3 months ago and now I am gaining. I have taken phentermine on and off for years. What can I do to boost the effectiveness so that I can loose the 15 lbs that I have gained back in the past 3 months?

  23. I started on the 14th this month taking the 30mg first week I had energy and just didn’t wanna eat but would make myself eat a little. Second and third week on it I just had dry mouth real thirsty all the time but now it’s gone I’m hungry but watch my calories on an app my dr told me to use while on on phentermine and I feel it’s stopped working – I go back to see my dr on the 14 of april

  24. I quit taking it because of the side effects I was experiencing. How long does it take for the side affects to stop now that I’ve quit taking it?

    • Hi Shannon,
      The side effects should stop within a few days to a week of you stopping the medication. If the side effects persist, consult your doctor.
      Sally, phentermine.com

  25. I went to my doctor about six months ago. I Explained to her that I workout 5-6 days a week and follow a fairly healthy diet. I eat pretty clean 6 days and take one day off. I am 45 and the lbs have slowly crept on. I went for a bunch of tests and everything came back negative. She wrote me a prescription for phentermine and I have lost 30 lbs. I am only allowed to be on it for 3 months and then I take a month off. When the weight loss slowed down we discussed it and she told me to manipulate it. In other words I had built up a tolerance so I need to take 2 consecutive days off to change my tolerance. It has worked but I know I am coming to the end of my prescription and need to have a maintenance plan without it. I have had only a positive experience. you cannot take this drug without doing the work. You have to workout. If you are not sweating, you are not working out. You have to eat right. Fruits. Vegetables. Protein. Real carbs. Lots of water. You will eat less. But when I am off the med, I can only maintain and not lose. I have 15 lbs to go. Is there something OTC that is I can take? And, Is there a maintenance plan for stopping phentermine?
    Thanks
    Meg

    • Hi Meg,
      Thanks for your message, and well done on your weight loss – it sounds like you have a great attitude! We recently published an article on how to avoid weight gain after phentermine, here is the link: http://www.phentermine.com/blog/not-gain-weight-phentermine/. Hopefully some of the tips should be useful to you!
      Sally, phentermine.com

  26. I started taking 30mg phentermine on 3-6-16. Immediately it suppressed my appetite and had more energy. As of today, I have lost 15 lbs. I drink tons of water that I didn’t before, and eat better and less. However, I guess my expectations were for greater weight loss. I am 57 years old and also take levothyroxine. My activity level is a little better than it was before starting phentermine, but not huge. Am I expecting way too much for a person my age? The side effects I’m experiencing are insomnia and slight dizziness once in a while. Any thoughts?

    • Hi!
      Losing 15lbs in about 6 weeks is really great – this is over the average 2lbs a week, so you’ve achieved a really good steady rate of weight loss. To help with your insomnia and dizziness we have some articles on here with tips and advice, and upping your activity level a little more should help to keep your losses steady and will also help with the insomnia too. Good luck!
      Sally, phentermine.com

  27. I have PCOS and was prescribed 37.5 mg of phentermine and had tons of energy the first day but everyday after that I can’t get through the day without a nap, why is that with someone with PCOS?

  28. Hello! I started taking Phentermine on April 5th. As soon as I took it I felt great! I was energetic, it suppressed my appetite, no cravings. I felt great! I lost 5lbs the first week & about 3 the next following week. So roughly I’ve lost about 9lbs. But, since then I haven’t lost anything. In the past week in the half my weight has fluctuated between 1 to 2lbs and that’s it. Also, I don’t feel anything anymore. I feel the way I did before taking the pills. I feel as my body has gotten use to the pills. Now, since day one of taking the pills I workout 5-6 days a week, I eat 6 times a day & consume 1200 calories a day and drink tons of water. So, what am I doing wrong? Do I need a higher dosage? Or maybe stop taking the pills for a few days then get back on them? I’ve always been a pretty healthy eater. But, I love sweets! & that’s one of the reasons why I got on it to reduce cravings…. I so desperately want to lose weight.

  29. Can I buy Phentarime online safely?

    • Hi Sarah,
      Phentermine is a prescription-only medication so you would need to speak to your doctor to see if he or she will prescribe it to you. This article explains more about the process of getting a prescription, and what to do if you can’t get one: http://www.phentermine.com/blog/how-can-i-get-phentermine/
      Sally, phentermine.com

  30. I started my weight-loss program in September of 2015, after I gained 40 almost in 6 months due to a personal tragedy. I also have thyroid issue, so my doctor suggested that I try Phentermine with diet and exercise. I have started taking half a pill a day because it made me dizzy, my heart was beating too fast, and I was irritable plus constipated. i lost 20 lbs.
    I stopped taking it for 2 month since January, but at least maintained or was losing 4-5 lbs and gained back when it was time for my period.

    To make a long story short, I did lose about 20 lbs by taking half a pill a day, with 30 min of exercise, and portion control. I still struggle with picking healthier food, so I hit a plateau for the past month a half.
    My doctor gave me a new prescription fro six month for Phentermine 37.5, so this time I started taking 2/3 of the pill to a full pill a day. my irritability increased, and I still exercise but my appetite is normal. It’s actually strange because I didn’t have sweet-tooth before, but now I do. Also, now I menstruate every 2-3 weeks so my appetite is uncontrollable during this time. I feel like taking phentermine just causes my period more irregular, irritably increased, and my appetite is uncontrollable craving for sweet and salty snacks during periods. My weight stays about the same or I am 3-5 lbs heavier even with exercise and diet.
    I would like to lose another 20 to go back to mt steady weight, but I feel like this pill does not work anymore other than causing me to have period all the time, and worsen other side effects.

    Should I get off of this pill for some time, finish what’s left before I go back to my doctor or should I keep taking it???

    Could someone give me some advise please?

    • Hi Natalie,
      Is phentermine helping you at all, with appetite suppression, cravings or giving you more energy? If you feel that it is helping you in any of these ways then it’s worth continuing with, but if you don’t feel any positive effects then it would make sense to speak to your doctor. There are other methods and diet pills that may be better suited to you, so it seems better to give those a chance than to continue with something that’s not working.
      Sally, phentermine.com

  31. Hi Sally,
    Thanks for the informative reply. Yes, Phertemine helps me postive effects: my appetite has decreased especially in the morning and I don’t have any cravings for food until I get off work.
    Now I have noticed I see a little more at night. So in the beginning it was easier for me do to portion control becuase it was working great the first time around. I still get more energy like I drank 3 cups of coffee already (and of course I have to 2-3 cups of coffee int he morning) due to my thyroid issue. It makes me feel like I took a caffeine pill so I am very energetic in the morning.

    I think the thing that I CANNOT STAND is that I have period every 2-3 weeks maybe due to overactive blood-flow in my system?? and when I am on period I crave for a lot of sweets….which is very unlike of me, and I get so very Mean that my friends/family thinks there is something wrong with me. I can control my mood swings on most day except when I have my periods….this is driving me crazy…
    I think maybe I will finish off what I have plus one more prescription and then go back to see my doc to find out if there is an alternative.

    Thanks again – this is very helpful to me !

  32. Hi Sally,
    I started taking Phentermine on 05/19/16 and I was doing great at for the first 4 days I had lost 8 pounds, then I came on my period for a week and I gained 4 pounds. When I came off the four pounds came back off within 2 days, but since then I haven’t gained or lost. Do you think I should stop taking them for a couple days and start back? I go to a boot camp class 4 days a week for 45 minutes I definitely do eat as much. I just feel like I’m taking pills for no reason. I can’t understand how I was loosing 2-3 pounds a day to not loosing anything within 3 weeks.

    • Hi Resheena,
      Firstly, it’s not a good idea to weigh yourself so often as then you get the wrong idea about how weight loss works. It’s not possible to really lose more than about 2lbs per week of actual fat, so anything you saw at the start was likely to be some fat but then also water weight. If you look at the average you’ve lost it’s 8lbs in less than 3 weeks, which is actually a really good rate of weight loss. The fact that you’re exercising means that you’re probably building muscle, especially with a boot camp class, so fat loss you may have achieved could be hidden by you gaining lean muscle, which will lead to a slimmer more toned body – much more important than how much you weigh. However, if you feel that phentermine isn’t suppressing your appetite or boosting your energy though then you could try to see how you go without it.
      Sally, phentermine.com

  33. Thanks Sally,

    I know I need to stop weighing myself everyday, but I’m kind of waiting to see myself at least lose 1 more pound first. My trainer tells me that everyday lol. I just don’t understand why so many people are losing so much more weight in their first 3 weeks and I’m not. I also had 2 Lipo shots since I started, its like that’s not helping much either. I know 2 pounds a week is safe and healthy, but how will I ever lose 50 pounds in three months like all these other people are? What do you think I’m doing wrong here? Is there something stronger then phentermine? Oh, also my friend went to a different weight loss clinic, and they gave her a water pill called hydrochlorothiazide 25MG and she loss 10 pounds in 2 days, my weight loss clinic is telling me they don’t provide water pills because its not healthy taking them with Phentermine. Is this true? Can I buy these over the counter? I believe if the water pills weren’t healthy the other clinic wouldn’t be giving them to their patients either. What do you think?

    • Hi Raesheena,
      Prescribing water pills alongside phentermine is something we sometimes see on the forum. It’s a way to lose water weight, but they can lead to dehydration and a loss of precious electrolytes, which can be dangerous. For someone taking phentermine, which is already a dehydrating drug, this really isn’t a good idea. Your friend’s weight loss is an indication that she lost a lot of water weight in that time, this was not fat. It might appear that she is doing better than you but it’s false advertising – when your body gets used to the water pills, your kidneys start to overcompensate and retain more sodium, meaning water retention, swelling and weight gain. I know it’s disheartening but in the end, slow and steady really does win the race. Comparing yourself to others won’t help – losing 50lbs in 3 months isn’t the average, plus these people often have a lot more to lose overall. To boost your weight loss, try to look more at what you’re eating and drinking and how you can improve your lifestyle – things like stress and sleep often get overlooked but they can hold the key to weight loss and good health too.
      Good luck!
      Sally, phentermine.com

      • Thank you sally your right! I will do better with my diet, and exercise. I’m happy I didn’t go to that place then, I don’t want any kidney problems in the future. You have help me so much. Thanks:)

      • Oh and sally how often should I get on the scale? 🙁

        • Hey,
          Once a week is usually enough – try and make it around the same time of day and before eating or drinking anything, such as first thing on a Monday morning. If you do weigh yourself more often, try to remember that there are many factors which influence weight any given day, including the amount of salt you had the day before, how much water you drank, where you are on your menstrual cycle etc. If a disappointing weigh in is likely to have a de-motivating effect then it’s best to keep it to once a week. If you want to check progress, taking photos, measuring yourself and trying on old clothes to see if they fit you better can all give you a better idea than just weight. And, be sure to make a mental note of how your physical condition is improving, so if you feel yourself making progress in your boot camp classes, such as running faster, feeling less out of breath, be able to do more push ups etc, then these are all signs of improved health, and should be celebrated – no matter what the scale says!
          Hope that helps!
          Sally, phentermine.com

          • Thank you so much, that’s a big help.

  34. HI today is my 8th day with the medication, I lost 5 lbs but I got stuck and can’t lose any more. I’m worried because I have chest pain, and shaky hands. My job doesn’t allow me to do a lot of exercise but I walk 10,000 to 13,000 steps average per day, I drink a lot of water, but the weight just didn’t want to decrease. I started with 159 lbs now I’m on 155.8 – my clothes fit now but the weight number is still there and my headaches are very bad lately

    • Hi Alex,
      The chest pain sounds like it could be serious, we would advise you to tell your doctor immediately.
      Sally, phentermine.com

  35. omg i took it 7 years ago and lost 80 freakin pounds! i started back over a year ago and havent lost a freakin pound AND im able to fall asleep and take a nap a couple hours after taking it, when i first took it i would be in full on cleaning mode all day!!! i would actually run out of things to clean so i would start reorganizing things just to make use of all the energy i had.

  36. Is depression a common thing with Phentermine? I have had to lower my dose to 1/2 a pill a day bc if I take a whole pill I start to feel depressed. It’s the strangest thing! I want to lose weight so bad but 1/2 a pill doesn’t suppress my appetite enough for an entire day. Is there anything I can do please?

    • Hi Samara,
      Yes, depression and mood swings are both common phentermine side effects. We would advise you to speak to your doctor to see if there is something he or she can suggest for you to achieve a happy medium between these side effects and the appetite suppression. Switching to time-release capsules could help, or some people find pills by different manufacturers can give them different side effects.
      Sally, phentermine.com

  37. Hi I started taking the medication April 15, 2016. As of today I have lost 32 pounds, eat very healthy and have changed my overall lifestyle. I was wondering if taking other products like multi vitamins, omega plex and other enhancements can affect the rate that you lose weight? I work in a doctors office so the scale is always there for me to weigh myself. I only take the 30mg and go back to the dr July 19. I am totally exhausted by the end of the day and at this point my weight has not changed in 3 weeks, go up a pound then down 5 etc.. I use advocare products and thought maybe that is what is haltering me to cont to loose. Any advice??

  38. I started taking 15mg of Phentermine along with 50mg Topamax last Friday, June 24th. I have lost 7 lbs so far, from 141 to 134, but my clothes are much tighter and I feel like I’m about to faint all the time. I’m so tired and dehydrated but I’m drinking water all the time. I cannot go to the bathroom at all. My doc took me off all carbs so I can’t even have fruit or even a sweet potato, just meat and veggies. I am miserable. Is this normal?

    • Hi Laura,
      A no-carb diet is likely to result in a low mood and a lack of energy, and it seems very extreme for someone who isn’t even heavy – even if you’re under 5 foot you’re still barely overweight. I don’t know why your clothes feel tighter if you’ve lost weight, so I’m not sure how to explain that but the tiredness and dehydration are probably related as phentermine makes you very dehydrated and tiredness is sign of dehydration. I would ask your doctor about whether you can just take the phentermine as it could be the addition of the Topamax making you feel so bad. Good luck!
      Sally, phentermine.com

  39. in the article it says that i can boost my Phentermine with phen caps so its safe to take them together right?

    • Hi Yuliya,
      Yes, it’s safe to take Phen Caps alongside phentermine. Phen Caps are a phentermine alternative but as they contain different ingredients, they use different mechanisms in the body to suppress appetite and boost energy. They also have no side effects or risks so they will not have any negative effects on your body or health.
      Sally, phentermine.com

  40. I’m feeling so frusterated. I started phentermine on May 11. At 248 lbs. Im a 5’5 female that has been diagnosed with hashimotos 14 yrs ago. I used to be small and maintained my weight very well. It was after my 4th child that my thyroid went to hell, and the weight just kept packing on and on. And absolutely no energy.
    So now I’m on Phentermine 37.5. Started at 15 with no results, then 30, no results. But 37.5 was doing great, my doctor even got my thyroid medication leveled out so my T3 and T4 are reading just a tad bit high so my energy levels don’t dip drastically because my thyroid levels change very quickly. Anyways from May 11 to August 11 I’ve gone from 248 to 212, awesome right. Ya but from the middle of July until August 11th was a nightmare. HUGE PLATEAU, I’ve been very active since starting the phentermine, more and more active as the weight comes off. But nothing was happening. Lots of exercise, treadmill 1 hr a day at the speed of 3.6 as fast as my short fat legs can carry me, then into a run until I feel like i would pass out then a slower walk to cool down a bit then a complete repeat. After an hr I’m on the floor with crunches, situps, leglifts, squats. Literally busting my butt as I should be to get the weight off. And I’m struggling to get the weight off with very little results. I’m on high protien low carb, sugarfree diet. My eating habit is not a struggle, in fact I find if I do eat something higher in carbs I get very sleepy. So anyways I broke that plateau by just a few lbs in July. Now from August 11 to now, HUH FORGET IT NOTHING IS WORKING. I take the vitamins that I’m suppose to, I drink plenty of water, still work out, everything as before. Now I’ve tried eating more, then tried eating less. Nothing is working, when I think I’ve broken the plateau I will go down in weight 3lbs then 2 days later ITS BACK like a reoccurring nightmare. I cant even say I’m losing inches because my clothes are fitting the same way every time I put them on, not the slightest bit looser. My goal weight is to be 140, i have a looong way to go. And now even longer because I cant seem to break the curse that other people don’t seem to have a problem with THE BIG PLATEAU. Is my body just use to the Phentermine now? Should the doctor add another weight loss pill with it. Should I stop for a while? I don’t have any side effects with it at all accept dry mouth which is not that bad. So I’m needing any advice at all. I’m desperate and depressed.

    • I know what you mean… My Dr put me on welbutrin with the phentermine …the combo support to work well but its not doing much more me … I feel so dead … Dragging myself around feeling like I have weights dragging behind me all day… I didn’t feel hungry I felt sick and wanted to curl up in a ball and cry all day… I would pass out from 4ish to 7ish everyday with a weird headache all day …. After 7ish I felt better like it wore off… Than I was like starving until I felt that stomach noises and all I wanted was a big fat plate of anything …I didn’t care what it was ..it’s food…. I hate that I can’t get past this … I spent a lot of money into a gym…($700) for the past year to end up like this … And my Dr expects me to lose the rest of 30lbs and I just struggling 🙂 that feeling of not getting anywhere just sucks… I been trying everything and overweight is a huge problem in my family … Like over 600lbs …I thank God I wasn’t that heavy at 4’11” but I was well over 200 after my son was born… Before I was 110lbs … I spent the last 20 years investing in exercise eating healthy lifestyle and it took me 15 years to drop down to 198lbs then I yoyo like CRAZY from 174-200 for 10 yrs now … And now I am at 140-150 yoyo again …. I am worried that I am never going to lose the rest of my weight and keep it off…

  41. My experience:
    Took 37.5 every other day for about 9 months… worked wonderfully, boosted my energy, suppressed my appetite. Made diet, exercising and dropping almost 80lbs much easier. Got injured, stopped taking it because I couldn’t work out and didn’t want to become immune… spiraled into a depression because the weight started coming back… then when my injury was fully healed, working out was VERY VERY hard compared to when I was on phentermine. Tried going back on phentermine recently but doesn’t give me the boosts at all anymore 🙁 gained most the of the weight back, still working at it, but I’m afraid I’ll have to do it all again, without the phentermine, much slower going.

  42. I have been taking phentermine for a month now…..I have lost 9 pounds…..my weight loss has came to a stop…. No matter what I do….I eat protein everyday….and I’m very active…..I only needed to lose 30 pounds….I’m 5 ft tall and was 155….help 😣

    • Hi Tiffany,
      First of all, it’s actually really common to experience a plateau after taking phentermine for 3 or 4 weeks – we get questions from blog readers and on social media with the same problem every week. The good news is that it’s just a sign that your body is adjusting to weight loss and will continue again after a quick breather. But you can take steps to help encourage your body to lose weight again. Here are some reasons why you might not be losing and how to overcome them: http://www.phentermine.com/blog/why-not-losing-weight-with-phentermine/
      Sally, phentermine.com

  43. I been on phentermine since October 2015 to current….I just finished with it as of yesterday… Within 24hrs I am starving and noticed my jeans don’t fit me like they did..I feel heavy miserable and fighting this off has me moody… I been jugging water and I noticed I am very sleepy… As of yesterday I was busy running all over … Did my workout and felt good and ate good foods as if today I am 100% the opposite …idk what to do… Last time when Dr took me off for 3 months ….I gained 25 back within 3 weeks ….I had to work twice as hard to not gain any more!! …I was 198- down to 143 lost 55 lbs and went back up super fast in no time…. I started back up only agreeing I take welbutrin 150mg with it and I feel super weird on the combo …like I’m tired but not …does that make sense??? What can I do to get past this … All my weight is in my waist now … I look like a pregnant potato with skinny arms and legs

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