What Phentermine Does to Your Period

Phentermine may cause irregularities in your period, resulting in a worsening of your monthly symptoms, due to its action on your hormonal levels. In this article we will describe what phentermine does to your period and how to deal with the symptoms.

It may not be registered as a phentermine adverse effect, but plenty of hearsay exists about women experiencing menstrual cycle changes while on this drug. Below is a list of symptoms reported by female Phentermine users:

  • Late periods (delayed for more than five days)
  • Missed periods (absent flow for over 40 days)
  • Early periods (appearing five or more days than expected)
  • Heavy flow or longer duration of periods
  • Light flow or shorter duration of periods
  • Incidence of spots or short bleeding in-between periods
  • Reduced number of period cycles (Oligomenorrhea, 4 – 9 periods in 12 months)
  • Increased number of period cycles (Polymenorrhea, over 17 cycles in 12 months)
  • Increased symptom severity – premenstrual syndrome (PMS), cramps, dizziness and nausea.

What these period alterations mean is that the physiological process of menstruation has been dysregulated, resulting in a changed symptom profile compared to what was the norm for you before starting phentermine.

We understand that experiencing symptoms such as these may alarm you, however, by letting you know that this is a common finding amongst female phentermine users we hope to reassure you, and also stress the importance of the phentermine forum in the provision of trusted information regarding this drug.

What is the Mechanism behind Phentermine’s Influence on Your Period?

Similarly to how phentermine has been associated to hair loss, it is believed that phentermine results in period changes indirectly, through the way in which losing weight affects hormonal levels that regulate your menstrual cycle.

Excessive weight loss, something common with phentermine use, decreases estrogen levels in the body, since this hormone is closely associated with the number of fat cells present in the organism. Lower estrogen results in the alteration of the menstruation process, which appears as period irregularities or even complete pause.

Another proposed mechanism implicates the stimulation of the sympathetic nervous system; by triggering the “fight or flight” state, reproductive hormone production decreases, resulting in the afore mentioned symptoms and signs. On the other hand, some phentermine adverse effects such as period irregularity, spotting or increased flow may be explained by the stimulating effect of the drug on the heart muscle. A heart that beats faster causes the blood flow to increase, ultimately leading in overloading the endometrium’s ‘spiral arteries’; this over activity ultimately results in more frequent periods.

Another factor leading to menstrual cycle dysregulation is malnutrition, stemming from the inability to follow a diet of adequate variance, probably because phentermine acts as an appetite suppressant. It doesn’t matter whether you work out or how much you weigh, inadequate ingestion of zinc, iron and healthy fatty acids may all affect your period and enhance the severity of period symptoms such as nausea, dizziness and cramps.

How to Cope with the Symptoms

If you haven’t been eating properly while taking phentermine, then this could be causing your period symptoms. Starting on a multivitamin supplement for the duration of your phentermine treatment, will make sure that no essential nutrients are missing from your diet, which may also aid in the resolution or dampening of the unpleasant menstrual symptoms.

As a matter of fact, by ensuring adequate ingestion of minerals and vitamins, you will also get to your weight loss goals easier, since you will be providing your body with everything it needs to keep your metabolism burning. Along with your vitamins, you should always aim for a diverse diet plan, packed with healthy food choices such as dark green leafy vegies, lean meats and also nuts and seeds that will aid you in better handling the unpleasant symptoms.

If you are in a situation where pregnancy is a possibility, you should make sure to use a birth control method, because phentermine is contraindicated in pregnancy. If you choose an oral contraceptive, then you may find that it helps you cope with the severe symptoms of menstruation, such as cramps and PMS. The birth control pill is usually prescribed by doctors to those women whose periods are accompanied with pain and heavy flow, however, it is preferable to allow at least 4 periods in on year, to maximize their chances of being fertile in the future.

By opting to not have a period on a monthly basis, you will be somewhat relieved from the adverse effects that phentermine has on your menstruation. Furthermore, fewer periods mean less symptoms associated with that time of the month, like cravings, bloating and weight gain, which ultimately will motivate you to continue taking phentermine.

Finally, if period irregularities are something you have been accustomed to, plus you have had trouble with your weight and were bothered with symptoms like cramps, fatigue, constipation, acne or infertility, then you should get screened for medical conditions such as thyroid disease and PCOS (Polycystic Ovary Syndrome), both known to affect hormonal levels.

Dealing with period irregularities and other more serious side effects is nothing to joke about, however, improving your health by following a proper diet and shedding excess weight with the help of phentermine, will aid you get past these problems eventually. Keep in mind that as you approach your weight goals, your body will get used to the modified hormonal levels, normalizing your period cycle and dampening the severity of your symptoms.

Last updated: May 6, 2022. Bookmark the permalink.

43 thoughts on “What Phentermine Does to Your Period

  1. I suffer from heavy flow and irregular period. Not sure if Phentermine is the cause or not. Are there any other factors that causes heavy flow and irregular period?

  2. Before starting phentermine, my menstrual cycle had always been irregular. I had very long and heavy periods that lasted anywhere from 7-10 days and always experienced light spotting in between cycles. I always assumed that being over weight was the cause of my irregularity, because when I was a teenager and thinner, I didn’t have these issues.

    I started Phentermine just a couple days after starting my period, and since starting, I literally have not stopped bleeding. It’s difficult to know where my period ends and the “spotting” begins. But I can always tell when my period is about to start because I still experience cramps and PMS cravings and increased hunger. When my period starts it’s extremely heavy and there’s a lot of very large blood clots. The heavy flow only lasts 3-7 days, at which I feel the period ends, and from there it’s only light “spotting” until my next period starts. I put spotting in quotes because some days I don’t bleed at all, and then others it’s a light flow like I’m on my period.

    This is my second time being on Phentermine. The first time I was on it, I was in my early teens and only weighed 280 pounds, and I didn’t experience any menstrual differences, except maybe missing my period once or twice. This time around I was 400 at my heaviest, but right now I’m at 350. At this point in time, I haven’t brought up the menstrual issues with my doctor, because I haven’t experienced any dizziness or lightheadedness from the blood loss, and I’m taking extra iron to combat anemia. The benefits definitely outweigh the inconveniences of menstrual irregularity, because I am already 50 pounds down, and I’ve got 150 more to go. I have 3-4 more months of my Phentermine to go, and I’m not giving up now!

    1. I’m having the exact issues you described above, however I’m not willing to put up with the constant bleeding and want to stop phentermine. Did your cycles return to normal/did the bleeding stop after you got off the medicine? Thank you for sharing your experience!

  3. I was supposed to get my period and I started taking phentermine and I had cramps kept thinking it was coming and nothing . I still have not gotten my period and it seems that is a common thing with this pill.

    1. My period is 2 days late for no reason and I’m freaking out. I’ve been taking the phentermine a little over a month now and I’ve had some financial stress recently but that has eased slighlty as I started a new job and am back working but playing catch up and now this missed period is freaking me out.

      1. Hi Jasmine! I’m seriously experiencing the same issue right now! Do you mind me asking if it was ever resolved? Were you pregnant? Or have you just stopped having your period because of Phen? Did you stop the medication and your period came back? Did it start late at all? Etc.. thanks!

        1. I have been over 2 weeks late for the last 3 months. Went to the hospital one the first one to get blood work done because I was freakIng out so bad. Not pregnant. Definitely the phen.

        2. I’m now in a similar situation. I’ve been on phen for a month now and I’ve never experienced a missed period prior to using the pills a few years back. I’m now 16 days late and I’ve taken 2 pregnancy test and both read negative. So reading that it might be normal while taking them, brings me some relieve. But did your period ever go back to normal or did it stay irregular the whole time in the pill? And did it go back to normal after getting off? I’m so appreciative of any info you can give me

          1. I went to my ginecology just for regular check up and for some reason that i dont even know, the doctor gave me phentermine. Inlost some weight but i havent get mybletiod for two weeks. Its late. I was never late on my period, always regualr. Now i am fucking freqking out to get mybperiod back. I qm not pregant, i did the pregnancy text. So i am not taking this medicine anymore. I rather be fat than this medicine mess up mynperiod. I dont care. So i am stopping it completely. I hope i get mybperiod. I even constipated now, i have cramps for fucking 3 weeks and my period dont come. So fuck that. I am not doing it. So ladies, becaugul ehat uou take. I rather lose weithh on my own by doing exercise and not earing at night time. That. Thanks

      2. How many days did it take until your period came? Are you still having delayed periods? I’m asking cause I’m going through the same thing right now.. and it’s really making me crazy

        1. I just began Phentermine and my period is late and I’m freaking out. I feel so much better that you all are also experiencing this side effect.

  4. Currently, experiencing heavy flow with the phentermine! I have heavy clots and not sure should I take an iron supplement just in case. I am a little concerned but, that is normal! I am used to not having much of a period so this is very different! Reminds me of when’s i was in Job Corps and my period was like a faucet that would not stop! I do like the Phentermine and that I am eating less! I will contact my doctor tomorrow and find out what she would like for me to do about the heavy flow. This is the first time happening in a long time! Any insight?

  5. Since I’ve been on Adipex, my periods have came early. Each time on cycle day 25, and they have been shorter and lighter. It makes me think it’s skipping ovulation.

    1. I just began Phentermine and my period is late and I’m freaking out. I feel so much better that you all are also experiencing this side effect.

  6. Since being on Phentermine my cycle has become short 21-23 days and my period is longer which i HATE lasts from 6-7 days!!! It used to be 4-5 days. This completely SUCKS! It also pops up what seems to be every 3 weeks !! I can’t stand it !

  7. I just took only half a Phentermine pill for the very first time and my menstrual just came to an abrupt stop. Is that possible?

    1. Two years ago on the recommendation of other moms, i went to the local diet pill clinic. I took 1/2 phentermine tablet for 3 months.I lost weight quickly. My whole life i have had regular light to moderate periods that last 4ish days with no cramping. Immediately upon stopping phentermine, I had the most God awful period of my life. It lasted 2 weeks, was full of enormous egg sized clots, heavy like a hemorrhage. I soaked stained everything and horrible cramps.
      I have never had another period since.

      My hair fell out and grew back in white.
      I had sores on my body and face in the last weeks.
      I smelled foul.
      It caused me to go into rages in the last two weeks and was suicidal.

      I’m still trying to restore my health from the experience.

  8. I’ve been taken Phen for abt 4weeks and it originally caused my menstrual to be 3 days late and this time it was four prior to taking it I had a regular 26 day like clock work menstrual for 6 days with last just being a day of spotting. My cramps and back pain are way more intense and the menstrual pimples have increased but my menstrual was only 3-4 days. So, I’m curious to see how this plays out considering I’m still interested in using Phen but I do thing I’m going to add the multi vitamin as suggested.

  9. have been experiencing abnormal spoting since started duromine was freaking out untill i read some comments…but will i go back to norm after discontinuing….

  10. I have been taking Adipex for 2 months now.. my periods have always been irregular. Since taking Adipex I am now REGULAR like clock work on my period.. I was at 223lbs and now at 185. Trying to get down to 145lbs. Before me and my husband start having kids!! I no longer have cramps or bloat when my periods start.. soo.. it sounds like Adipex has a different effect on people!!

    1. I’m on the phentermine. I was 223 and now I’m 155! I haven’t checked I believe I’m smaller now. It’s not hard KEEP GOING GIRL !!

    2. Hey Rayvin! Can you tell me your secret? That’s a huge weight loss for 2 months…what do you eat? Do you work out? Hope to hear from you!! 🙂

  11. I have been on adipex going on 2 months. I had my youngest son June 4, 2018. Started adipex 3 weeks after having him. I’m glad I did some reasearch. Never thought that adipex could be why my period is so out of wack. I had been talking to my ob and they told me to start my birth control. I did. It seemed to slow it down but I kept spotting then I got really bad back pain almost like a kidney infection. So I stopped my birth control and the back pain stopped but now I am bleeding very heavily again. I don’t want to stop the adipex but I want to have normal cycles again!!!!‍♀️

  12. Ok so here is my problem,
    My periods have always been regular 4-5 days since taking these pills axcion for about 1 month, and I haven’t gotten my period I’m late 2 weeks and I took a pregnancy test and came out not pregnant so what is it.!?

  13. Okay so my period is a week late and I have been taken Phentermine. My cycle has never been late always have been early or on time and I have took a pregnancy test and it saying not pregnant so I have stop taking them and since my cycle has been late should I continue to take dem or wait for my cycle

  14. My doctor warned do not yet pregnant …but I late…what do I do if I am… every time I go for the pill , he says do NOT get pregnant…freaking out…what does it do to baby in the beginning of pregnancy. I am probably about 3 weeks ,not sure

  15. I have been on and off adipex for years. After having my daughter in 2013 and stopping breastfeeding in 2014 I got back on birth control and adipex in 2014. I had regular periods for awhile, but for the last 3 years I haven’t had a period at all which I thought was caused by my birth control pill, but I think adipex cause it. Last Thursday, 1/03/2019, I started back on adipex after being off of it for 4 months and I am still on birth control too and on 1/03/2019 my period came full force in the middle of my birth control pack. No discomfort, but this is a moderate flow and today is day 5 with no end in sight for this cycle after 3 years of no period. I need to lose this weight, but I sure did enjoy not having a period for 3 years and I wish this period would end already considering I am taking my pill every day!!!

  16. I just started phentermine 2weeks ago and I have this severe premenstral cramp and menstral cramp. This has been the worst cramp ever in my life time. Please what can I use to stop this cramp. It is too painful.

  17. I’ve taken Phentermine before and I recently started again, I’m five days late on my period and I’m freaking out cause I’m never late. I took a pregnancy test and it’s negative. Last time I took the pill this didn’t happen

  18. I started phentermine in Middle of February. I always had a very normal Cycle lasting 3 to 4 days for with just spotting on the 4th day. My February cycle was very painful lots of bleeding cramping and it lasted for 9 days. I thought that was odd. But I figured at 40 maybe I’m going through some changes. Then in March my cycle Came 10 days early and I’ve been bleeding for 10 days I went to researching what’s been different in my life and the only thing different is the Phentermine. Even though I lost 18 pounds in the first month I don’t think it’s worth it to me to have these irregular heavy periods

  19. Im freaking out i have not gotten my period in 2 months . i started taking phentermine march3rd i believe and. I usally get my period on the 22-27 . idk what to do . my mom gets me pills . a doctor never prescribed then to me 🙁

  20. My period has been a little irregular since I had a miscarriage in October of 2018. My last cycle in March of this year I was 2 weeks late just because. It’s very confusing. I started taking Phentermine 2 weeks ago, I am on a low calorie and low carb diet, and I just started working out 6 days a week. About a week ago I stated to have nipple sensitivity and it is getting a little more intense. I took a pregnancy test yesterday because I was worried about it, and it was negative. (I am now on cycle day 39.) I know that while on Phentermine you can experience a huge change in you cycle and increased pms symptoms, so I was hoping someone else has experienced this as well. It’s just hormones because of the meds and my body isn’t used to the food consumption and exercise? Please tell me this is normal.

  21. I took 1 pill of Duromine on the 30th of March. I was suppose to get my period on the 10th of April. My period is regular and has never been this late before. This will be 2 weeks since the day I was suppose to get my period. I started to freak out but I took 2 pregnancy test and came back negative. So does anyone no if u get ur period anytime soon or does it differ to different people?

  22. This is the second time I’ve been on Phentermine’s it is May 28th and my last period started on March 19th. It is just starting again today. I’m not sure how I put two and two together but last time I was on the Phentermine I was two months late when I finally got it. I guess this is normal though. Good to know.

  23. Hi i had my periods on the 14th feb 2020 and finshied 19/02/2020. I started taking duromine on the 23/02 (2 days today)and i hve started bleeding again. No cramps just heavy flow. Is this normal

  24. I took phentermine 37.5 for three days and started bleeding. I already finished my period two weeks ago. I should be ovulating. My dr. Wants me to lower the dosage to 15mg. I really need to lose weight. I’m very disappointed.

  25. I started taking phentermine August 12, that’s 2 weeks and 6 days so far.
    I have spotting/light period for 15 DAYS straight!!! I don’t know when it will stop. My doctor who prescribed the phentermine said it’s normal to have bleeding. I eat less now and my body is not used to it so my hormone levels are acting up. I am freaking out because I never had spotting/period this long I will call my gynecologist tomorrow for consultation.

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