Management of Diarrhoea

Assessment / monitoring

Acute (< 4 week duration)

Red flags: Blood in stool, nocturnal symptoms, recent antibiotics, travel abroad, immunosuppression.

Consider: Exposure to possible enteric infection (undercooked food, recent farm visit), other symptoms such as abdominal pain / fever / vomiting, new medications, high risk groups (nursing home residents, food handlers).

  • Examine hydration status.
  • Bloods for FBC, U&Es and CRP.
  • Three stool samples for C. difficile, ova, cysts and parasites.
  • IV fluids / oral rehydration (avoid oral magnesium replacement).

Chronic (>4 week duration)

Red flags: Nocturnal symptoms, iron deficiency anaemia, rectal bleeding / bloody diarrhoea, weight loss, raised inflammatory markers, severe abdominal pain, immunocompromised patients.

  • Three stool samples for C. difficile, ova, cysts and parasites.
  • Bloods for FBC, haematinics, U&Es, CRP, TFTs, coeliac serology, HIV test.
  • Review medications (e.g. metformin, oral magnesium, NSAIDs, ACE-inhibitors, antibiotics).
  • Consider qFIT and / or calprotectin.
  • Consider GI or surgical referral or direct to test colonoscopy if qFIT raised.

Treatment Options

Therapy Dosing advice
Oral rehydration salts e.g. Dioralyte® 1–2 sachets after every loose motion. Each sachet is reconstituted with 200ml of water.

4mg initially followed by 2mg after each loose stool, up to a maximum of 16mg daily.

N.B. Do not give if infection or inflammatory bowel disease is suspected.

Note: If C. difficile is suspected, see here for management. 


Guideline reviewed: May 2023

Page last updated: December 2023