Suprep usually starts working within 30 minutes to 4 hours after taking the first dose. Most people begin to experience multiple urgent bowel movements in that time frame, although individual responses vary depending on factors like metabolism and hydration. The second dose of Suprep may work faster since the first dose has already cleared a significant portion of the bowel. People can continue to have bowel movements for several hours after the prep begins to work.
In typical use, the first dose is taken the evening before a colonoscopy, and the second dose about four hours before the procedure, with strict instructions to stop all liquids at least three hours before the procedure.
