Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Sulfamethoxazole is a sulfonamide antibiotic: it blocks bacteria from making folate, which they need to grow. It is almost always given together with trimethoprim (co-trimoxazole, Bactrim, Septra), which blocks the next step of the same pathway, for urinary, chest and skin infections and to treat and prevent Pneumocystis pneumonia.
Sulfamethoxazole is inactivated partly by NAT2 and turned by CYP2C9 into a reactive product thought to drive its hypersensitivity reactions; slow NAT2 acetylators were linked in older studies to more such reactions. In people with G6PD deficiency, sulfonamides can cause haemolysis. Studies have also looked at GCLC, which helps make glutathione. The findings come from a few studies, and there is no CPIC or DPWG guideline.
Every published finding on gene variants and Sulfamethoxazole. Upload your DNA file to see which of these rows apply to you.
PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.
G6PD G6PD B (reference), G6PD Canton, Taiwan-Hakka, Gifu-like, Agrigento-like: Level 3. Toxicity: Hemolysis. 3.
GCLC rs761142: Level 3. Toxicity: HIV infectious disease. 1.
Studies of how quickly the body processes this medication.
Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.
More drugs from the same category
Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.
Content updated September 2026.
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