Hiprex contains the active substance methenamine hippurate and belongs to a group of medicines called anti-bacterial. These work by killing many different types of bacteria that cause infections. Hiprex is used to treat infections of the urinary tract and stop them from coming back. The urinary tract is a collective name for the parts of the body that produce, store, and transport urine. These include the kidney, bladder, and tubes called the ureter and urethra. It is also used to avoid urinary tract infections (UTI ) in patients with catheters from their bladders (a tube that helps with incontinence) and in people undergoing certain medical procedures.