Colon cleansing (colon therapy) encompasses a number of alternative medical therapies intended to remove fecal waste and unidentified toxins from the colon and intestinal tract. Colon cleansing may take the form of colon hydrotherapy (also called colonics or colonic irrigation) or oral cleansing regimens.

Colon hydrotherapy uses enemas to inject water, sometimes mixed with herbs, or other liquids, into the colon using special equipment. Oral cleaning uses dietary fiber, herbs, dietary supplements, or laxatives. Practitioners believe that accumulations of putrefied feces line the walls of the large intestine. These accumulations are said to harbour parasites or pathogenic gut flora and to cause nonspecific symptoms and general ill-health. This “auto-intoxication” hypothesis is based on medical beliefs of the Ancient Egyptians and Greeks, and was discredited in the early 20th century.

No scientific evidence supports the alleged benefits of colon cleansing. The bowel itself is not dirty and barring drugs or disease, cleans itself naturally without need for assistance. Some types of colon cleansing present potential hazards; the equipment used during colon cleansing has caused damage to the rectum in a small number of individuals, and caused amoebiasis when improperly sterilized. Certain enema preparations have been associated with heart attacks and electrolyte imbalances. Frequent colon cleansing may interfere with the proper functioning of the colon and can lead to dependence on laxatives or enemas to defecate. Some herbs used may also interact with or reduce the effectiveness of prescription drugs.