In general, children under 18 months of age can be given a glycerine suppository. Children between 18 months and 9 years can either be given a Fleets enema or 1/2 of a Dulcolax suppository. Older children can be given a regular Fleets enema or a whole Dulcolax suppository.
Up to five cases of acute hemodynamic deterioration, including one death, have been associated with the use of milk and molasses enemas for constipation in children. The four children who recovered required aggressive resuscitation. [J Pediatr Gastroenterol Nutr 2003;36(1): pp.144-8]
In children, you should avoid the regular use of an enema or suppository and try to solve the problem dietarily. The infrequent use of a water only or saline enema is considered safe.
The occasional use of an enema in an older child or adult should not result in any complications. If a coffee enema is indicated, it will not only help your liver, but produce a healthy evacuation as well.