Dulcolax suppositories contain a medicine called bisacodyl this belongs to a group of medicines called laxatives dulcolax suppositories are used for the relief of constipation dulcolax suppositories are also used in hospitals to clear the bowel before surgery x rays or other tests dulcolax suppositories stimulate the muscles of the bowel large intestine helping to return the body to its natural rhythm they have a laxative effect within 30 minutes what is constipation normal and regul