1.4 Acute diarrhoea

1st choiceOral rehydration therapy (Dioralyte®)Doses:
According to fluid loss, usually 200–400 ml solution after every loose motion. Reconstitute 1 sachet with 200 ml of water
Loperamide capsules 2mg; syrup 1mg/5mlAcute diarrhoea, 4mg then 2mg after each loose stool for up to five days. Maximum 16mg daily
Chronic diarrhoea, 4-8mg daily in divided doses adjusted to response. Maximum 16mg daily in 2 divided doses

Prescribing Notes

  • The priority in acute diarrhoea is the prevention or reversal of fluid and electrolyte depletion and resulting dehydration. This is particularly important in infants and in frail and elderly patients.
  • The cause of diarrhoea should be identified before starting symptomatic treatment.
  • Loperamide is preferred to codeine phosphate because it is less likely to produce central side-effects and addiction.
  • There have been reports of serious cardiac adverse reactions with high doses of loperamide associated with abuse or misuse (see MHRA for further details). However, specialist GI centres may sometimes recommend doses higher than the licensed maximum to control high output stoma.
  • Antidiarrhoeal drugs should not be given in acute inflammatory bowel disease or pseudomembranous colitis, as they may increase the risk of developing toxic megacolon, nor in acute infective diarrhoea with bloody stools.


  • Faecal impaction can give rise to ‘overflow diarrhoea’ and must be excluded before antidiarrhoeals are started.
  • Review medicines that can precipitate kidney failure in acute dehydration, e.g. ACE inhibitors, NSAIDs. Consider withholding these medicines in patients who become ill and are unable to maintain adequate fluid intake. See Sick Day rules for further information.
  • Loperamide is an opioid and therefore caution is needed in patients with a history of drug abuse as addiction is observed with opioids as a class.