Methenamine is a urinary tract antiseptic that is used as suppressive therapy for chronic or recurrent urinary tract infections. Methenamine has not been linked to serum enzyme elevations or to instances of clinically apparent acute liver injury.Methenamine is a heterocyclic organic compound with antibiotic activity. In the body methenamine is converted to formaldehyde, a nonspecific bactericidal agent. Methenamine is typically used long-term to treat chronic urinary tract infections and to prevent the recurrence of infections.