Sulfathiazole is a short-acting sulfonamide with properties similar to those of sulfamethoxazole. It is now rarely used systemically due to its toxicity. Sulfathiazole is used with other sulfonamides, usually sulfabenzamide and sulfacetamide, in preparations for the topical treatment of vaginal infections and is also used with other drugs in the treatment of skin infections. Sulfathiazole sodium has been applied topically with other drugs in the treatment of eye infections. Sulfathiazole interferes with nucleic acid synthesis in microorganisms by blocking the conversion of p-aminobenzoic acid to the coenzyme dihydrofolic acid.It has properties similar to sulfamethoxazole.