rules of thumb

Last reviewed 01/2018

The following guidelines may help in the differential diagnosis of diarrhoea:

  • copious watery diarrhoea suggests an organic aetiology
  • nocturnal diarrhoea suggests an organic aetiology - patient wakes up in the night needing to open bowels
  • frequent passage of small amounts of faeces suggests functional bowel disease, e.g. irritable bowel syndrome
  • bloody diarrhoea implies colonic disease, often inflammatory bowel disease or carcinoma, or an invasive infective diarrhoea, e.g. Campylobacter jejuni
  • acute diarrhoea often has an infective aetiology