Sulfamethazine is a sulfonamide consisting of pyrimidine with methyl substituents at the 4- and 6-positions and a 4-aminobenzenesulfonamido group at the 2-position. It has a role as an antiinfective agent, a carcinogenic agent, a ligand, an antibacterial drug, an antimicrobial agent, an EC 2.5.1.15 (dihydropteroate synthase) inhibitor, an environmental contaminant, a xenobiotic and a drug allergen. It is a member of pyrimidines, a sulfonamide and a sulfonamide antibiotic. It is functionally related to a sulfanilamide.