My wife began taking 30mg Phentermine in June 2015 and after 5 months moved up to 37.5mg. She does not exercise but we both have a healthy diet. She has lost 30 pounds but she is a completely different person. I looked up the side effects and noticed irritability was on the list, but in the past year irritability is just a small part of what I've noticed. Since taking this medication she has changed. There is so much anger and displeasure not only with me but everyone she works with. The smallest thing can set her off and even if it's dealt with or fixed right away she is unable to move beyond it. She dwells on things often becoming more angry days or weeks after the original issue had already been resolved. There is nothing else I can think of in the past year that could have caused the personality changes I've seen.
Please help me and let me know if anyone out there has seen or experienced similar behavior from a loved one who has taken Phentermine.
How bad can the irritability and mood swings be when taking Phentermine?
Question posted by NeedHelp702 on 1 May 2016
Last updated on 23 June 2025 (1 week ago) by MeganM1456
The information on this page reflects personal experiences shared by our community members. It is not reviewed for medical accuracy and should not replace professional medical advice.
20 Answers Page 2
I have been taking Phentermine on and off for several years starting in 2015. I was 19 years old when I first starting taking it, now I'm 24 years old. I noticed the mood swings right away when I found myself questioning my irrational behavior. I did a lot of research and didn't find anything super helpful. My doctor told me she had heard other patients saying the medication had made them easily annoyed and aggressive. She claimed to not understand why though. Out of the 3 or 4 different times I've taken this medication I've noticed the mood swings to be rare or completely diminished when I was exercising regularly and staying away from caffeine. I believe that having that much energy and not burning it off is going to cause you to become over stimulated and therefore extremely irrational.
There is a point during the day where you come down from the effects of the drug wether you've burned all the energy off or not because our bodies can't handle a hyperactive state for too long. This "come down" happens rapidly. When I say rapidly I mean I would basically be in a manic state, experiencing a positive "I love life" mood then not even 30 minutes later I was ready to tear anyones head off that came near me. Sometimes I would still be manic but it would be more violent or aggressive. This can be very dangerous if you're not willing to exercise and burn off the energy or reduce the amount of phentermine you take. THIS IS NOT AN EASY COP OUT SOLUTION TO LOSE WEIGHT! I gained the weight back the first few times because I was relying on the pills to keep the weight off. Guess what. If you don't change your eating and exercise habits you're still the same lazy f*ck you were 30 lbs ago. Get off your butts and do something besides popping pills. Tell your stubborn wives to read this. If she doesn't wanna change then she's probably a selfish b*tch and always will be.
I was on this weight loss drug as well, I worked on a job that I loved. I lost that job due to phentermine I had gotten paranoid and very suspicious of my supervisor, I would feel like she was trying to get me fired, I had made a couple mistakes at work and I was convinced that someone got into my account and made the mistakes in hopes of getting me fired! One day I thought my supervisor was following me and also the Human Resources lady as well. I went to the weight loss Dr. where I had gotten the pills and I asked him if the pills caused you to become paranoid, he told me no and that if anything they make me alert, I believed him. On my 6 year anniversary at my job I was fired because when my job did an investigation on my computer to see if someone in fact had been using my account to make mistakes they only saw where I had been signing in and no one else.
Afterwards of course I continued to take the pills because I believed what the Dr told me and I went into depression crying and very very sleepy my cousin tried helping me get a job at the hospital where she worked but I was in no shape to even think about finding another job. Two days before my wedding I stopped taking the pills I had gotten back to 120lbs (I had went through a lot of stress a couple years back and had gained slot of weight I had gotten to 160 lbs never had I ever gotten that big except when I was pregnant with my kids) on my honeymoon I started experiencing stomach pains and diarrhea really bad but I still didn’t figure out it was the pills I thought I had food poisoning the pain and diarrhea continued even when I got home one day I woke up on the toilet didn’t know how I got there no one was home I had a trail from my bed to the toilet I must’ve passed out on the toilet. I called my dad and he took me to the hospital they didn’t really do anything they checked me and dismissed it as a virus that needed to run it’s course... it was soooo bad I had to wear a diaper to school (I couldn’t control my bowels) I finally started feeling better and stopped my bouts of crying and started feeling like myself and I stared doing research on the pills and i found out that the pills do if you take them for a long period of time in my case it was non stop for about 6 months! They will cause mild schizophrenia and with in a year I went from 120 lbs to 193lbs after I stopped taking the pills I couldn’t control my eating I could never get full..
I started taking these pills and I notice my mood swings right away and a sadness comes over me it's only been a few days so I haven't notice any weight loss but this is a bad side affect
BEWARE! This drug is powerful in changing your mood and personality! Yes, I lost weight but it’s just not worth it and I ended up gaining it back anyway. I got this medicine prescribed to me by a weight loss doctor and was so anxious to lose weight that I didn’t even do research on it. I literally popped it in my mouth as I walked out of his office. During the next week I was starting arguments with my husband that ended in rage and tears. I still didn’t put it together though. So as I was fighting with him and not going home fully ready to almost end the relationship I was still popping these pills three times a day as instructed. Finally, it dawned on me to research the side effects and sure enough it described my dramatic mood swings on various sites. I must say, it wasn’t easy to find though.
With obesity a huge problem in our society surely this drug is extremely profitable allowing the manufacturers to hide negative reviews online. I stopped taking the drug and started to feel myself again. Thank God my husband loves me enough to have seen through it! Well, that was not enough. After a couple weeks I convinced myself that perhaps I could take it again if I just took LESS. Instead of 3 pills a day I only took half in the mornings. That shouldn’t be so bad right? I told myself I would only take it long enough to loose 15 pounds. I made it halfway losing 8 pounds but I also lost complete control of my emotions too. I couldn’t calm myself to think clearly. I was suspicious and paranoid. I got myself (and my support system) worked up to the point where I made legal decisions that affect both mine and my husband’s lives and even ended up in the hospital for 5 days because I became suicidal! Please do NOT use this drug! Please find a healthier solution for losing weight. You may think you can handle it like I did but it really does sneak up on you and makes your sanity slip right through your fingers like water trickling through no matter how tightly you clench your hands. I was making important decisions as if I was a robot believing stories I created in my head, awake many nights with a fast heartbeat and overworking mind focused on protecting myself. All the while, this drug is what I needed to protect myself from! I wish you luck on repairing any damage you may have made and loving your body as you find healthier ways to transform it. I have learned my lesson the very hard way to be more cognizant of what I put into my body.
Please let me start by expressing my empathies. I found out that my wife of 18yrs was/is taking this nasty little drug. Lying next to her one night with one arm wrapped around her I felt her heart beating rapidly. Easily I estimated a resting heart rate of 130-140 BPM. I asked her why? No answer. Thought it was very odd. So through a little investigation of my own the next day I went though her medications and picture ID each one of them. Phentermine came up and I realized it from the combination "Fen/Fen" regretfully used about 25yrs ago by many individuals across the country. Through further research on the drug, ALL of the symptoms of RAGE, ANGER and disdain that she exhibited were found and more. The smallest issue set off the most cataclysmic reaction that resulted in her bringing up every issue that made her upset in the last 18yrs even if it wasn't accurate or true. Read the reviews online about this drug.
Many women expressed becoming depressed and regret destroying their perfectly fine relationships by affairs or divorce. Mine verbalized the space and separation idea a year ago and after a month became mellow and back to normal. I can only assume she stopped taking the drug. Oh and sex resumed. A year later it's back with a vengeance. Seems like she's back on it. Plus she's menopausal. Confronting her about this would probably really be the last straw. I'm gonna have to for the sake of our son. In speaking to a pharmacist it seems that this drug is popular among older women.
Related topics
phentermine, diet, exercise, irritability, mood swing
Further information
- Phentermine uses and safety info
- Phentermine prescribing info & package insert (for Health Professionals)
- Side effects of Phentermine (detailed)
Similar questions
Search for questions
Still looking for answers? Try searching for what you seek or ask your own question.