Sulfasalazine is a DMARD used to treat various autoimmune diseases and diabetes. Learn about its working, common side effects, available medicines and expert advice on 1mg.com. Sulfasalazine is a medication used to treat ulcerative colitis, rheumatoid arthritis, and Crohn's disease. It can cause various side effects, interact with other drugs, and have serious warnings and precautions. Learn more about sulfasalazine dosage, administration, and brand names. Sulfasalazine , a sulfonamide, generally is considered a prodrug since the diazo bond is cleaved in vivo to provide sulfapyridine and 5-aminosalicyclic acid (mesalamine); the drug exhibits antibacterial and anti-inflammatory activity. Sulfasalazine is a sulfonamide drug used to treat rheumatoid arthritis, ulcerative colitis, and Crohn's disease. It is broken down by intestinal bacteria into sulfapyridine and mesalazine, which have anti-inflammatory effects in the colon.