Colonic irrigation or colon hydrotherapy, also known as a colonic, is an alternative medicine practice which involves flushing the colon with warm filtered water. The colonic removes a buildup of waste which supporters of the practice believe is harmful for digestive and general health. Practitioners and frequent patients claim that regular colonics keep them healthier, and that they are less prone to digestive problems. Most doctors trained in conventional medicine do not recommend the use of colonics for any medical condition, although enemas to cleanse the lower colon may be appropriate in certain situations. Studies have not suggested that a colonic would be harmful to a healthy individual, unless it was administered in unclean conditions.

According to practitioners of alternative medicine, fecal matter builds up in the colon and interferes with the body's ability to absorb nutrients. It is believed that this causes the digestive system to become inefficient, leading to an assortment of health problems. Receiving a colonic is supposed to address this problem by removing buildup along the length of the colon. Certain people should not consider getting a colonic, including people with intestinal issues such as Crohn's Disease or hemorrhoids. Pregnant women should also avoid colonics, and if you are unsure about whether or not a colonic is safe for you, consult your doctor.

A colonic sessions starts with a brief intake form and interview with the colon hydrotherapist, who will go over the procedure and talk about any issues the patient may have. The patient changes into a gown and lies on a padded table so that the colon hydrotherapist can insert a sterile, single use speculum attached to a length of tubing into the anus. The colon is gently flushed with repeated doses of warmed water, which loosens waste stuck in the colon and filters it out through a closed tube system. When the colonic is over, the therapist leaves to allow the patient to use a toilet and get dressed.

As with any complementary alternative medicine practice, it is important to go to a reputable practitioner who has been properly trained. Traditionally trained doctors and nurses can administer colonics, along with doctors who have trained at alternative medicine schools. In both cases, the colon hydrotherapist will have an extensive knowledge of anatomy and biology, and will have attended training on how to use the equipment involved safely. Several trade organizations of colon hydrotherapists exist around the world, and are happy to assist potential patients with referrals.