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 28 July 2025 (4 weeks ago) by apcraider2
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21 Answers Page 2
My husband and I are now separated due to this drug. It has destroyed our marriage and the relationship with the kids. He has become angry at all of us and everyone around him. I am so sad. I am seeing things go bad. The drug is horrible. He claims he is off of it but the years of hurt it has caused is unreal. I’m sorry for anyone else who has to deal with this.
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.
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.
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.
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.
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)
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