Methenamine is a urinary antiinfective medicine. Methenamine fights bacteria in the urine and bladder. Methenamine may be used to treat and prevent urinary tract infections. Methenamine may also be used for purposes other than those listed here.
Methenamine mandelate is a prescription drug used to prevent and treat infections of the urinary tract. It is classified as belonging to the antiseptic drug class. Methenamine mandelate is not used to treat active infections and you may have to use other antibiotics to treat an existing condition first. Also, it may not work for viral and bacterial infections.