Dulcolax tablets provide gentle, predictable overnight relief of occasional constipation. Take 1-2 Dulcolax tablets before bed for relief the next morning. Dulcolax® (bisacodyl 5mg) works by stimulating the bowel muscles while also accumulating water in the intestines. The effect is to soften the stool and to make it pass through more quickly. Dulcolax is Doctor Recommended, and has been clinically proven to provide effective relief of occasional constipation.