Methenamine is a medication used to prevent or treat urinary tract infections. It is also known by the trade name Urex, Urinary Antiseptic and Hiprex. Other synonyms for methenamine include hexamethylenetetramine, hexamine, urotropine, and hexamethylenetramine. Methenamine works by converting to formaldehyde in the urine, which acts as a bactericidal agent against various strains of bacteria that can cause urinary tract infections. As a result, methenamine is a widely used medication for preventing and treating recurrent urinary tract infections. Patients should consult with their healthcare provider before taking methenamine to ensure the medication is appropriate for their individual needs.