This medication relaxes the muscles of the urinary tract. It is used to relieve pain, burning, urinary urgency and frequency and other symptoms associated with urinary tract infections, bladder infections and prostate infections. Urispas (flavoxate HCl) tablets contain flavoxate hydrochloride, a synthetic urinary tract spasmolytic. Flavoxate hydrochloride counteracts smooth muscle spasm of the urinary tract and exerts its effect directly on the muscle. In a single study of 11 normal male subjects, the time to onset of action was 55 minutes. The peak effect was observed at 112 minutes.