An enema (/ˈɛnəmə/; plural enemata or enemas) or clyster, is a fluid injected into the lower bowel by way of the rectum.

The most frequent use of an enema is as a cleansing enema (also called a soapsuds enema) which is given to relieve constipation or for bowel cleansing before a medical examination or procedure. In standard medicine an enema may also be employed as a lower gastrointestinal series (also called a barium enema), to check diarrhea, as a vehicle for the administration of food, water or medicine, as a stimulant to the general system, as a local application and, more rarely, as a means of reducing temperature as treatment for encopresis, and as a form of rehydration therapy (proctoclysis) in patients for whom intravenous therapy is not applicable.