Trimethoprim is an antibiotic.
It's used to treat and prevent urinary tract infections (UTIs), such as cystitis.
Occasionally, trimethoprim is used to treat other types of infections, such as chest infections and acne.
Trimethoprim is available on prescription. It comes as tablets and as a liquid that you swallow.
Key facts
- You'll usually take trimethoprim twice a day to treat infections.
- For most infections, you'll feel better within a few days. It's important to finish your course of trimethoprim to help stop your infection from coming back.
- Side effects may include itching or a skin rash, but these are usually mild and do not last long.
- You can drink alcohol while taking trimethoprim.
- Tell your doctor if you do not start feeling better after taking trimethoprim for 2 days, or if you start to feel worse at any time.