The enema tube and solution may stimulate the vagus nerve, which may trigger an arrhythmia such as bradycardia.
Enemas should not be used if there is an undiagnosed abdominal pain since the peristalsis of the bowel can cause an inflamed appendix to rupture.
There are arguments both for and against colonic irrigation in people with diverticulitis, ulcerative colitis, Crohn's disease, severe or internal hemorrhoids or tumors in the rectum or colon, and its usage is not recommended soon after bowel surgery (unless directed by one's health care provider).
Colonics are inappropriate for people with bowel, rectal or anal pathologies where the pathology contributes to the risk of bowel perforation.
Enema comes from Greek ἔνεμα (énema), from ἐνίημι (eníēmi), "(I) inject".
Clyster (/ˈklɪstə(r)/), also spelled glister in the 17th century, rarely "cloister" or "clister" comes from Greek κλυστήρ (klystḗr), from κλύζω (klýzo), "(I) wash".
It is an archaic word for enema, more particularly for enemas administered using a clyster syringe – that is, a syringe with a rectal nozzle and a plunger rather than a bulb.
Clyster syringes were used from the 17th century (or before) to the 19th century, when they were largely replaced by enema bulb syringes, bocks, and bags.