Dulcolax Tablets 5mg are for the effective short-term relief of constipation. The gastro-resistant coating on Dulcolax protects the tablet until it reaches the colon. It then dissolves bringing gentle overnight relief in 6-12 hours. They have a gastro-resistant coating which ensures that they get to work only where they are needed gently stimulating the muscles in your bowel. Dulcolax Tablets contain bisacodyl 5mg.