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justin_vargas2026-04-18

I was prescribed Trimethoprim 100mg Tablets to treat a urinary tract infection. This antibiotic is commonly used to stop bacterial growth, which has been effective in treating my infection. However, I'm worried about the potential side effects. The leaflet mentions urgent side effects like allergic reactions, methemoglobinemia, and electrolyte problems. How common are these? I've also heard about C. diff-associated diarrhea. Has anyone else had a similar experience with this medication? I want to be prepared and know what to watch out for besides just the common symptoms.

1 min read
last active 4/18/2026
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Comments (9)

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abigail_andrews4/16/2026

This thread is giving me PTSD just thinking about it. I took it a couple of years ago and had to deal with a case of CDAD. Not an experience I’d ever want to repeat. Thanks for the warning, everyone.

J
joe_james4/16/2026

Just don't take it with milk or antacids. It can reduce the effectiveness. I learned this the hard way.

L
lauren_knight4/16/2026

The methemoglobinemia symptoms are scary stuff—my cousin had a bad reaction with blue lips and shortness of breath. He was in the hospital for a week. Doctors said it’s rare but possible, so be careful.

J
jonathan_hamilton4/16/2026

Just make sure to stay hydrated if you take it. Dehydration can amplify some of the side effects. I remember my doctor telling me to drink lots of water.

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sean_williams4/16/2026

I took it for a UTI a few months back and had pretty bad diarrhea. I ignored it at first but it got so bad I had to call my doctor. They told me it could be C. diff and to get checked out. Finally got it sorted out after a few days of treatment. Super scary and was a wake-up call to take antibiotics seriously.

J
justin_robertson4/16/2026

Trimethoprim is a solid choice for UTIs but be cautious with the side effects. I once took it and had problems with dizziness and headaches.

M
martha_fox4/16/2026

I had a severe allergic reaction to it – ended up in the ER with hives and difficulty breathing. Not fun, but thankfully I was able to get help quickly.

K
kenneth_jordan4/16/2026

The leaflet’s scary stuff. And do note the FDA reporting part if things go south. I worked in a hospital and saw some people have really bad side effects from antibiotics. Physicians always emphasize reporting any unusual symptoms.

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elena_vargas4/16/2026

I've been on it a couple of times and never had any serious side effects. Just the usual stomach upset and diarrhea. I found that taking it with food helped a lot.