Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Sulfasalazine is an anti-inflammatory medicine made of two parts joined together: in the gut, bacteria split it into 5-aminosalicylic acid, which calms inflammation in the bowel, and sulfapyridine, which acts on the immune system more widely. It is used for ulcerative colitis and for rheumatoid arthritis. It is sold as Azulfidine and Salazopyrin, among other names.
The sulfapyridine part is inactivated by the liver enzyme NAT2. Slow acetylators, with two low-activity NAT2 copies (about half of people of European ancestry), keep more of it, which is linked to more side effects; the US FDA lists this pair. The US label also mentions G6PD deficiency, because sulfonamides can break down red blood cells in people who have it. Studies have also looked at the transporter ABCG2 and immune genes, with weaker evidence.
Clinical guidelines that name a gene for Sulfasalazine. They sort people into groups by the gene copies they carry.
US FDA: G6PD. Deficient · Deficient with CNSHA · Variable.
US FDA: NAT2. Poor Metabolizer. Data that Indicate a Potential Impact on Safety or Response.
Every published finding on gene variants and Sulfasalazine. 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.
ABCG2 rs2231142: Level 3. Metabolism/PK. 3.
MTR rs1805087: Level 3. Efficacy: Rheumatoid arthritis. 1.
G6PD G6PD A- 202A_376G, G6PD B (reference): Level 3. Toxicity: Hemolysis. 1.
ABCG2 rs2231142: Level 3. Efficacy: Rheumatoid arthritis. 1.
Studies of how quickly the body processes this medication.
NAT2 NAT2*4: NAT2 *4/*4 is not associated with clearance of sulfasalazine in healthy individuals.
Studies of how well it worked in people carrying a variant.
Studies of how much of the drug people needed or tolerated.
Studies that do not fall into the groups above.
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
Agenerase (Protease Inhibitors)
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.
ReadYourDNA provides educational interpretation of DNA data you already have. It is not diagnostic, not a substitute for professional medical advice, diagnosis, or treatment, and is not intended to diagnose, treat, cure, or prevent any disease. Talk to a clinician before acting on any result.
Raw DNA Data Reports for 23andMe & AncestryDNA · About ReadYourDNA · FAQ · Methodology & Science · Pricing · Support and complaints · Legal & Contact · Health Traits · Pharmacogenomics · Carrier Status · Variant Explorer · The Human Karyotype · Privacy Policy · Terms of Service · Accessibility · Consumer Health Data Privacy · Your Privacy Choices · Editorial Standards · Your Data, Checkable · Sample Report · ReadYourDNA and Promethease compared · What is inside a 23andMe raw data file · What is inside an AncestryDNA raw data file · What a chatbot can and cannot do with your raw DNA file · Where a raw DNA file can still be uploaded in 2026
Written, maintained and operated by Martin Pechhacker, sole proprietor, Vienna, Austria. Trade register GISA 40064420. support@readyourdna.com