四環素是一種抗生素。四環素局部阻止細菌在皮膚上生長。 四環素被局部用於治療細菌感染如痤瘡。 
Tetracycline is an antibiotic. Tetracycline topical prevents bacteria from growing on the skin.
Tetracycline is used topically to treat bacterial infections such as acne.