Drug-Induced Diarrhoea: A Far From Rare Adverse Event

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Can Be Benign or Severe...

Antimicrobials are responsible for 25% of drug-induced diarrhoea.[1] The disease spectrum of anti-microbial- associated diarrhoea ranges from benign diarrhoea to pseudomembranous colitis.

Pseudomembranous colitis is rare but severe.[2] The mechanism is the emergence and proliferation of Clostridium difficile.[2] This micro-organism secretes 2 toxins which cause mucosal damage, inducing lesions and an inflammatory response. Antibacterials that reach high concentrations in the intestinal lumen and are active against bowel flora are more likely to promote overgrowth of C. difficile.[2] Aminopenicillins are responsible in 35% of cases of pseudomembranous colitis, cephalosporins in 30%, and lincosamides (clindamycin) in 15%.[1] Other antimicrobial agents occasionally involved include aminoglycosides, tetra-cyclines, macrolides, sulphonamides, chloramphenicol, imidazoles and quinolones. The increasing number of patients being diagnosed with Helicobacter pylori infection and treated with amoxicillin and other antibacterials may increase the incidence of pseudomembranous colitis.[3]

Symptoms of pseudomembranous colitis generally appear 5 to 10 days after the start of therapy, but shorter periods and longer delays up to 1 month are possible. The acute colitis can be severe with profuse diarrhoea (rarely with blood), abdominal pain and bloating, fever and a frank altered general status.

Mortality associated with pseudomembranous colitis has been shown to be 3% in one study[4] and is due to local complications (e.g. toxic megacolon, haemorrhage, perforation) or general complications (e.g. dehydration, shock, sepsis).


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