What is Senokot syrup  Senokot Syrup is a medication that relieves constipation temporarily and starts working the next day. Senokot Syrup might be the answer for you if you suffer from constipation and are looking for relief that will work quickly. How does Senokot Syrup treat constipation? Senna, a natural substance made from the leaves and fruit of the Senna plant, is the active ingredient in Senokot Syrup. By causing your bowel muscles to contract and your stools to go through your body more quickly, this natural chemical helps to treat constipation.