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Cotrimoxazole (Septran): uses, side effects & brands
Cotrimoxazole combines two antibiotics for urinary, chest and some other infections. It belongs to the Antibiotic (other) group. These antibiotics from various families treat specific bacterial infections; they do not work against viruses.
Drug type — dosing is set by your doctor
| Measure | Range |
|---|---|
| Drug class | Antibiotic (other) |
| Type | Prescription |
| Dose | Individual — ask your doctor or pharmacist |
What it is used for
- Urinary tract infections
- Some chest and ear infections
- Preventing and treating pneumocystis pneumonia (e.g. in HIV)
- Some gut and skin infections, and toxoplasmosis
Common brand names
- India: Septran, Bactrim, Ciplin
- Worldwide: Bactrim, Septra
Common side effects
- Nausea or loss of appetite
- Rash or itching
- Sensitivity to sunlight
Before taking it — precautions
- Contains a sulfa drug — tell your doctor if you are allergic to sulfa medicines
- Tell your doctor about kidney or liver problems, G6PD deficiency, pregnancy, or blood thinner (warfarin) and methotrexate use
- Drink plenty of fluids; blood tests may be needed on longer courses
When to see a doctor urgently
- Rash with blisters, peeling, mouth sores or fever (urgent)
- Unusual bruising, bleeding, sore throat or mouth ulcers
- Yellow eyes/skin, very dark urine or severe allergy (urgent)
Frequently asked questions
What is in cotrimoxazole?
It combines two antibiotics, sulfamethoxazole and trimethoprim, which work together to block bacterial growth.
Why do people with HIV take it daily?
It helps prevent certain serious infections, such as pneumocystis pneumonia, when immunity is low.
Why should I report a rash quickly?
Rarely, sulfa medicines cause severe skin reactions. Stop and seek medical help if a rash spreads, blisters or comes with fever.
Explore more
Sources & further reading
- World Health Organization (WHO)
- MedlinePlus — U.S. National Library of Medicine
- Ministry of Health & Family Welfare, India
- Indian Council of Medical Research (ICMR)
Reviewed by Dr. Sanjay Anbu, MBBS. MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.