Colon cleansing is done to prepare for medical procedures such as a colonoscopy. Before a colonoscopy, you'll need to clean out your colon because any residue may obscure the view of your colon and rectum during the examination.
Some alternative medicine practitioners offer colon cleansing for other purposes, such as detoxification. Proponents of colon cleansing believe that it improves health by removing toxins, boosting your energy and enhancing your immune system. However, there's no evidence that colon cleansing produces these effects or is beneficial in any way. And colon cleansing can be harmful.