About sulfamethoxazole + trimethoprim
Sulfonamide-antibiotic combination
Used for
- Urinary tract infections
- Certain respiratory infections, including Pneumocystis pneumonia
- Some skin and intestinal infections
Usual adult dose
Common infections: one standard tablet every 12 hours; dose and duration vary by infection.
Usual dose in children
For selected infections, dosing is based on trimethoprim 8 mg/kg/day, divided every 12 hours; clinician-directed.
Common side effects
- Nausea, vomiting, or loss of appetite
- Rash or itching
- Increased sensitivity to sunlight
- Diarrhea
Important warnings
- Rare severe skin reactions can occur; seek urgent care for blistering or peeling rash.
- Can cause serious blood disorders, especially with folate deficiency or prolonged use.
- Use may require dose adjustment in kidney impairment; maintain adequate fluids.
- Not suitable for some people with sulfonamide allergy or certain blood disorders.
Pregnancy
Use during pregnancy requires medical assessment; avoid near delivery because of newborn risks.
Breastfeeding
Small amounts enter breast milk; extra caution is needed with premature, jaundiced, or very young infants.
Interactions
- Warfarin: may increase bleeding risk.
- Methotrexate: may increase toxicity.
- Phenytoin: may increase drug levels.
- Potassium-raising medicines: may increase blood potassium.
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.