Supreme Klean 1-Hour Fast Flush Capsules begin working in one hour and are effective for up to five hours. The Fast Flush caps work as a flushing agent to cleanse your body of all unwanted drug metabolites allowing you to pass a urine drug test. After taking the Fast Flush capsules, individuals should be prepared to urinate frequently. This detoxifying product temporarily speeds up the urinary process during which the body releases the drug metabolites. Capsules remain effective from 1 hour after consumption up to 5 hours depending on metabolism and level of toxins in your system. Once the effects of the capsules have worn off the individual will continue to test positive for drug metabolites.