• There is a marked difference between an enema and a suppository; although in most cases a they work in a similar way. Both the liquid found in an enema and the glycerin in laxative suppositories work to lubricate hardened stools so that they pass more easily

Suppository laxatives: Small solid or semi-solid plug made from a particular type of medication e.g. glycerin. Generally safer. Can be used for a longer period with fewer side-effects. Should be moistened before use to aid insertion and placed alongside the bowel wall so that body heat causes them to dissolve and distribute around the rectum.

• Glycerol (Glycerin) suppositories (lubricating and weak stimulant). One PRN. Can be used for hard or soft stools (although solid, quickly melts once inside the rectum and provides lubrication for hard to pass stools.

• Bisacodyl suppositories (stimulant). Use for soft stools. Avoid if large, hard stools, as no softening effect.

• Sodium phosphate / sodium bicarbonate suppositories (e.g. Carbalax). Work by an effervescent action

Enema: A liquid that is inserted into the rectum using a nozzle attached to a bag made of plastic or cloth. The liquid is forced into the rectum through this device to relieve occasional constipation or prepare patients for surgery. Generally more effective at cleaning out the entire colon, as they have a farther reach and contain more medication with each use

• Docusate sodium enema (softener and weak stimulant). Can be used for hard or soft stools. Correct administration important to prevent damage to rectal mucosa.

• Sodium citrate enema (osmotic). Smaller volume (5 mL) than a phosphate enema (130mL). Useful to remove hard, impacted stools. Correct administration important to prevent damage to rectal mucosa. PRN use only.

• Phosphate enema (osmotic). Useful to remove hard, impacted stools. Correct administration important to prevent damage to rectal mucosa. PRN use only. Can cause hypocalcaemia and hyperphosphataemia in ill patients or in renal impairment. Can also produce rectal gangrene in ill patients with a history of haemorrhoids

• Arachis oil enema (softener). Retention enema; used overnight and warmed before use. Useful for hard, impacted stools. Should not be used in people with peanut allergy. PRN use only

Resources

• Constipation (BNF)​