Fleet Glycerin Suppositories provide fast relief. That"s because the suppository is inserted rectally, allowing it to act locally in the colon without having to go through the entire digestive system. Glycerin is a hyperosmotic laxative that attracts water into the stool and promotes bowel movement. Each suppository is easy to insert and produces a bowel movement within 15 minutes to an hour. Before using Fleet Glycerin Suppositories, be sure to review the drug facts.