Your Phentermine Questions Answered

phentermine questions

Here on the blog we do our best to provide answers to your phentermine questions by publishing quality articles specifically designed to help keep you informed about phentermine. However, to make it easier for you to find out exactly what you want to know, here we have put together some of the most common phentermine questions that we’re asked to give you all the answers you need all in one place.

1. Where can I buy phentermine?

You cannot buy phentermine – it is only available on prescription following a face-to-face consultation with a medical doctor. If you have a prescription, you can get it filled at most pharmacies.

2. Why is phentermine prescription-only?

Phentermine is prescription-only because it is structurally similar to amphetamine and is therefore classed as a controlled substance, which means that it is not advisable for people to take it without first having seen a doctor.  The doctor can then make sure that phentermine is suitable for you and will not cause any harmful effects, in addition to monitoring your reaction to phentermine and the progress you make during follow-up consultations.

3. What should I do if I can’t get a phentermine prescription?

If you’re not able to get a phentermine prescription, we recommend the phentermine alternative, Phen Caps. Phen Caps do not contain phentermine and are available without the need for a prescription here. Phen Caps contain a combination of active ingredients to suppress appetite and boost energy levels, meaning they are the perfect alternative to phentermine, as many satisfied customers have commented.

4. What are the side effects of phentermine?

The side effects of phentermine include headaches, nausea, insomnia, constipation and dizziness, but by far the most common is dry mouth, as indicated in a poll of phentermine users. Despite being a stimulant, phentermine can also evoke paradoxical side effects such as fatigue, in addition to psychological side effects such as low mood, anxiety and depression. If the side effects you’re experiencing continue for an extended period or become uncomfortable, or include severe side effects such as chest pain or trouble breathing then you should contact your doctor immediately.

5. How can I reduce phentermine side effects?

You can help to combat the side effects using these methods, and we recommend Phen Drink as the best cure for dry mouth, as it is specifically aimed at those taking phentermine with its combination of active ingredients which work to boost saliva flow and relieve the uncomfortable dryness, while also helping weight loss by suppressing appetite and boosting metabolism. The psychological side effects of phentermine can be worsened by a vitamin deficiency, so we also recommend that you take Phen Vites to make sure you have all the essential nutrients to stay healthy and optimize weight loss too.

6. Is phentermine dangerous?

Phentermine is only suitable for over-18s, and should not be taken if you are pregnant, trying to become pregnant, or if you are nursing. Phentermine is also not suitable for those who have a history of drug or alcohol Phentermine is an FDA-approved medication, and is perfectly safe as long as it is taken as prescribed. abuse, or if you suffer with glaucoma or heart disease, among other specifications which can be seen here. Phentermine is not to be confused with Fen-Phen, which was a combination of fenfluramine (fen) and phentermine (phen) and has since been withdrawn from the market, as has the ingredient fenfluramine.

7. What’s the difference between phentermine and Adipex?

Phentermine is the name of both the medication and the active ingredient in phentermine tablets and capsules, and is manufactured by a range of pharmaceutical companies. Adipex, officially known as Adipex-P, is a brand weight loss medication which also contains phentermine as the active ingredient and is manufactured by Teva Pharmaceuticals. As a brand, Adipex is often said to be more expensive than generic phentermine and some users have commented that Adipex is more effective than phentermine. However, other support group members conclude that this may be due to individual differences between patients as not all medication will work the same way for all people.

8. What is the difference between phentermine and Phen Caps?

Phen Caps are a phentermine alternative and weight loss supplement, which means that they do not contain phentermine, but instead utilize a combination of active ingredients to help you lose weight in the same ways as phentermine – by suppressing appetite and boosting energy levels. Phen Caps can be purchased online as they do not include anything which is prescription-only, plus they have no known side effects, however, they are widely recommended by customers as the best alternative to phentermine, and are also recognized as a great way to boost the effectiveness of your phentermine  towards the end of your prescription.

phentermine questions

9. Why has my doctor prescribed phentermine with Topamax?

Topamax, a topiramate, is sometimes prescribed alongside phentermine to strengthen the effects of phentermine. Phentermine and topiramate is an FDA-approved phentermine combination known as Qsymia. Some doctors choose to prescribe the two medications separately as opposed to prescribing the specific combination although this is essentially the same thing.

10. How does phentermine help me lose weight?

Contrary to what some people believe, phentermine is not a miracle pill which can help you lose weight without exercise or watching what you eat. Phentermine works by acting 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 energy levels and alertness, reduce appetite and minimize cravings, therefore encouraging you to eat better and feel more motivated to establish a daily routine of activity to continue for the long term in order to reach and maintain your goals to lose weight with phentermine.

11. When should I take phentermine?

If your doctor decides that you are suitable for a phentermine prescription, he or she should provide you with clear instructions for when to take it. Phentermine should be taken at the beginning of the day and normally on an empty stomach. These instructions will vary with different phentermine brands, but you should take phentermine exactly as prescribed by your doctor and follow all directions on your prescription label. If you work shifts or during the night, then it is always a good idea to explain to your doctor how you need phentermine to fit in with your lifestyle, such as taking phentermine in the afternoon when you wake up, so that its effects are optimized when you most need them.

12. What should I eat while taking phentermine?

You should see the time that you are taking phentermine as the beginning of a healthier way of eating to continue in the long term. The best way to do this is to establish healthy eating habits, such as eating several smaller meals, drinking plenty of water, and to incorporate healthy, filling foods into your diet, such as these, which will also help to maximize the effects of phentermine. However, allowing yourself to still enjoy the foods you love in moderation will ensure that you do not feel deprived and slip up by bingeing as a result of an overly-strict eating regime. Remember that you need to eat to lose weight, so make sure to follow the guidance of your doctor about calorie intake and never eat less than 1200 calories in a day.

13. Do I need to exercise to lose weight with phentermine?

To maximize your results with phentermine then it is recommended that an important goal is to include some kind of physical activity in your healthier lifestyle. Exercise is an important part of your weight loss journey, not just to encourage weight loss and toning but it can help to boost energy levels, suppress appetite, minimize side effects and menstrual cramping, and boost your mood and outlook on life. As opposed to the list of things you can’t eat, exercise also gives you something that you can do to help your weight loss journey, as a pro-active way to improve your body. It’s important that you don’t see exercise as a chore or something you have to do; find an exercise you love, whether it’s dancing, hiking, yoga, or just going for a walk to clear your head and you’ll be sure to make time for exercise, rather than excuses.

14. Should I take supplements with phentermine?

Many doctors now prescribe vitamin B12 and 5-HTP alongside phentermine to help boost the effects and also to help with some side effects, such as insomnia and fatigue. However, here are, we recommend specific supplements which have been designed especially for those taking phentermine. The weight loss multivitamins Phen Vites, are the only multivitamins especially designed for weight loss, and which contains both 5-HTP and B12 to boost the effectiveness of phentermine while also helping to reduce side effects. Phen Vites also include all the essential nutrients your body needs for maximum weight loss potential and optimum health and wellbeing. Phen Drink, specifically designed to stop the dry mouth side effect of phentermine, is another recommended supplement as it also boosts metabolism and helps make water more interesting with its great fruity taste but is totally free of calories, carbs and sugar. We also recommend the weight loss supplement Phen Caps, which are an alternative to phentermine and work excellently alone, but can also be combined with phentermine to boost your results, especially if you think your phentermine isn’t working as well as you had hoped.

We hope that we’ve answered all your phentermine questions, but please get in touch with us if you have any more questions by commenting below!

Similar Posts


    1. Hi Ava, thanks for your question! This really depends on many factors ranging from constants such as height and gender to measures which are always changing such as foods eaten that day. However, estimates state that phentermine stays in your system for up to 4 days – although if the body metabolizes phentermine particularly quickly then it can be out of your system in around 24 hours.
      Hope that helps!

  1. Hello, I have heard doctors are not prescribing it? Do you know of any doctors in Springfield MO who use it for weight loss for their patients?

      1. I am on my fourth week of taking Phentermine as apart of my journey to get to a manageable weight and BMI. My doctor only gave me a total of about 4 months to be on the pill, and I am a little worried about how my body will react when my time with it is done.

        Just out of curiously, I tried to “test” my body by not taking the tablets for two mornings in a row, and I experienced the worst midday to evening headaches as well as barely tolerable stomach cramps and small about of the “shakes” as if I was going through withdrawal from some sort of illegal substances.

        I made sure I ate, under the assumption that it would help with the “shakes” and the headache, but nothing completely took away those symptoms until I started back with the pill.

        I am a nursing student, so I do know that certain people become dependent on substances that are used to alter mental status/brain function. I am currently taking a 37.5 mg gel capsule, which I feel is working great. But, I was wondering if there was any sort of “step down” dosage for this drug that I may be able to ask the doctor about on my next visit. I think it would be better to sort of ween my body off instead of quitting cold turkey so that my body does not feel so dependent upon it.

        1. Hi Rita, thanks for your message.

          Firstly, yes there is a ‘step-down’ dosage for phentermine which is normally 15mg, and this is recommended as the last dosage before the drug is stopped, usually for the last month or two weeks and sometimes gradually being reduced to one pill every other day. However, it would seem that few phentermine users are actually prescribed this dosage at the end of their prescription, which may be the decision of the doctor in order to maximize their weight loss during the limited time that they are on phentermine. We would recommend that you talk to your doctor about your concerns of developing an addiction and your worries about withdrawal symptoms and he or she should then prescribe you with the appropriate dosage as you come to the end of your prescription.

          However, the addicting effects of phentermine also cause it to become less effective over time, so after 4 weeks you are probably still experiencing the full effects of the drug, however, after an additional 2 months, it’s likely that you will not experience the same strength of effects. Therefore, when you come to the end of your prescription, stopping it may not produce the same effects as you have recently experienced.

          Hope that helps!

  2. I have been taking it for 4 months and I have not lost anything in the past 2. It doesn’t seem to have to have the same effect. Can you build a tolerance, and should you look to increase your dose. I take the 37.5 1x per day.

    1. Hi Doug,
      It’s common to build up a tolerance to phentermine which is why it’s generally recommended for 3 months at a time, as taking a break ( can help your body to re-establish responsiveness to phentermine while also giving you the opportunity to practice self control and assess how you’ll get on without the help of phentermine. You shouldn’t increase your dosage unless you have been specifically prescribed more than 37.5mg per day by your doctor. If you feel that you need an extra boost then we would recommend that you continue to take your phentermine in the morning but combine this with Phen Caps to boost the effects of appetite suppression and energy. This article explains more about Phen Caps:

      Hope that helps!

  3. Will I see a change if I take a course of phentermine, stop, then start it again? Will I lose weight the same way as the 1st time?

    1. Hey Emy, thanks for your message! The idea with phentermine is to only take it for short periods – it is recommended for periods of 3 months and then in most cases, doctors will prescribe more if the patient needs it after a break of around a month. These time frames do vary but the concept of taking a break from phentermine is practiced by most doctors. Here you can read why you need to take a break from phentermine –
      Hope that helps!

    1. Hey Diane, to answer your two questions –
      1. you should always ask your doctor about taking other medications alongside phentermine as there is always a chance of an interaction. If the medication is for your health then you would not phentermine to compromise how well it works, and some over-the-counter medications can compromise the effectiveness of phentermine, so please make sure to ask your doctor if you are prescribed any other medications or plan to take any over-the-counter drugs.
      2. It is normal to be prescribed 15mg of phentermine to start with – the recommendations for doctors prescribing phentermine, and possibly any drug, are to start off at the lowest possible dosage and then increase this dosage only if it is necessary in order to reach the desired effectiveness. Many patients who are prescribed larger doses of phentermine find it too strong at first and have half their dosage or ask the doctor to prescribe a lower dosage. So, if you have been prescribed 15mg then you can rest assured that your doctor is following the correct practices. If you feel that it is not enough, however, then you should inform your doctor and he or she should be able to increase your dosage to 30mg or 37.5mg.

      Hope that all helps!

  4. I have traveled and left my 37.5 mg phentermine at home… I will be without for 4 days… What should I expect? Ok to start again on day 5?

    1. Hey Jenn,
      Thanks for your question. We’ve seen a few people in the Facebook group who’ve done the same so don’t worry too much. You’ll probably notice the difference with less energy and you will probably have a greater appetite than with phentermine, but you should try as much as possible to keep up the healthy eating and exercise regime that you started with phentermine. It will be hard but it’s a chance to see how well you do without the help from phentermine. And then when you get back just continue taking phentermine as before.

    1. Hey Rose, definitely not – you should wait until your baby is done with nursing before taking medications like phentermine. Ask your doctor for advice about losing weight and then when your ready, he or she may recommend phentermine as the best option.

      Hope that helps!

    1. Hi John,
      Phentermine produces a false-positive reading on drug tests for amphetamines, so you would need to either disclose that you take it before testing or stop taking it if it’s considered a banned substance.

    1. Hi MJW,
      It’s best to take phentermine as instructed by your prescription but if you feel that you could reduce your dosage or would like to take it less frequently then it’s best to consult your doctor before making any changes.

  5. I see on my pill that there is a break in half line….I just started phen 2 days ago with the 37mg…i feel a little wired , can I break in half to lessen the side effects. Thank you

    1. Hi Scotie,
      Yes, many people do this, especially at the start when the side effects can be particularly strong. It is a good idea to check with your doctor first though, just so he or she is aware of this.

  6. Hi:
    I am a 59 year old woman with low blood pressure and pre diabetic for which I’m on Metformin ER 500 twice a day. I am 5′ 6″ and currently at 210. I exercise regularly. I am currently taking the lowest does of Phentermine each morning. I plan to take it for 3 months as agreed with my Endo Doctor here in Southern Oregon. (My regular physician is not kicked out about me taking this drug, feeling it is too hard on even my healthy heart, but being short term she is okay and curious to see if effective). I also recently (Dec ’16) started taking Gabepentin for my restless legs and also possible peripheral neuropathy in my feet. Gabapentin, as you know, makes you relax. Am I playing with a big roller coaster risk of phentermine in the a.m. and Gabapentin in the late day and before bed. 400 mg x 2.? My endo doc didn’t seem too concerned since both are low doses. I’m a bit concerned.
    Carol in Oregon

    1. Hi Carol,
      If your doctor isn’t concerned then you should feel reassured that your body can handle this combination of medications. That said, it is important to be vigilant and consult your doctor if you experience any side effects or anything that concerns you or causes you pain.

  7. I was prescribed Phentermine 37.5 K25. I started today @ 8:45am! I don’t feel anything and I have been hungry all day!! Please advise me if anyone else has experienced and what did they do??

    1. Hi Paula!

      Have you consulted with your prescribing doctor? The only difference between generic phentermine and brand names are subtle differences, like additional flavoring, release method (longer or shorter times for body to process the drug, etc). IF you DO NOT feel the effects of the treatment, we urge you to contact your doctor for further assistance, as we are not qualified to give medical assessment.



  8. What kind of labs the Health Care Provider focus on before prescribe Phentermine to his/her patient, please?

    1. Hi Darline!

      Phentermine is intended to act as a weight loss aid for overweight individuals, and particularly those who have tried and failed to lose weight using other methods. It’s an option for patients with a BMI ≥30 (obese), or a BMI ≥27 (overweight) in the presence of other weight-related conditions. However, it is not appropriate or safe for all populations. For example, due to safety concerns, you cannot take this medication if you have a history of cardiovascular problems or if you are pregnant, breastfeeding or planning to become pregnant.



    1. Hi Morgan! We’re not sure about this, so we would recommend checking with your prescribing physician & pharmacist. You should NOT take phentermine while pregnant, so it’s important to determine for certain whether you’re getting a false positive or actually pregnant. Best wishes!

  9. Hi Sally. i was prescribed by my Dr. a few weeks ago…i am pretty healthy 48 year old with 3-year old twins that had gestational diabetes at the end of my pregnancy. my Dr, a cardiologist, surprisingly prescribed this to jump-start my system. i started with 1/2 a pill and initially felt a bit amped for the first few days. then when i felt stabilized i increased to dr recommended dose of a full pill in the am. i take at 7am and within an hour or two i am completely exhausted. like…can barely keep my eyes open or body vertical exhaustion. i did read about the occasional paradoxial reaction which rings true – but if i am having the opposite reaction, will it work/still be effective? Also, does this symptom/reaction go away, like the other side effects? please advise! i am walking around in a stupor (until late afternoon).

Leave a Reply

Your email address will not be published.