Acute diarrhoea

Definition and clinical types

Acute diarrhoea means at least three liquid stools per day for less than two weeks. The biggest immediate risks are dehydration and malnutrition.

Many cases are infectious and spread through contaminated hands, food, or water.

Assessment

• Assess dehydration first and classify severity using the dehydration pathway.
• Look for profuse watery stool, repeated vomiting, fever, visible red blood in stool, abdominal pain, rectal pain, reduced urine, altered mental status, severe weakness, and signs of malnutrition.
• In endemic areas, remember that malaria, ear infection, or respiratory infection can also come with diarrhoea.
• Assess age, pregnancy, comorbid disease, immune suppression, outbreak exposure, food and water exposures, household contacts, and ability to drink and return for review.

General treatment principles

• Prevent or treat dehydration promptly by replacing fluid and electrolyte losses until diarrhoea stops.
• Use ORS for patients who can drink safely; use IV fluids for severe dehydration, shock, or inability to drink according to the dehydration pathway.
• Continue unrestricted normal diet. Breastfed children should breastfeed more often; breast milk does not replace ORS, so give ORS between feeds.
• Prevent malnutrition with continued feeding and nutritional support when intake is poor or illness is prolonged.
• Treat underlying illnesses such as malaria, otitis media, or respiratory infection when present.
• Children with severe acute malnutrition need adapted rehydration and feeding protocols.

Zinc and antimicrobial decisions

• Give zinc with ORS in children under 5 years to reduce duration, severity, and recurrence risk over the following 2 to 3 months.
• Do not use antimicrobials routinely. Most non-bloody acute diarrhoea is viral and will not respond to antibiotics.
• Antimicrobials may be useful for cholera when resistance patterns allow, giardiasis, shigellosis, amoebiasis meeting criteria, or other confirmed clinician-directed diagnoses.
• For bloody diarrhoea without laboratory confirmation of amoebiasis, treat shigellosis first because it is the more frequent cause in many settings.
• Treat amoebiasis only when motile Entamoeba histolytica is found in stool or when correct shigellosis treatment has failed.
• Do not administer antidiarrhoeal drugs or routine antiemetics.

Prevention and follow-up

• Breastfeeding reduces infant diarrhoea morbidity, mortality, and episode severity.
• After weaning, reduce faecal contamination risk by discouraging bottle-feeding where unsafe, cooking food well, and avoiding storage of milk or porridge at room temperature.
• Safe water, sanitation, and handwashing with soap before food preparation, before eating, and after defecation reduce spread.
• Rotavirus vaccination is recommended in high-fatality settings according to national schedule.
• Return urgently for thirst, reduced urine, lethargy, repeated vomiting, blood in stool, high fever, severe abdominal pain, worsening dehydration, inability to drink, or diarrhoea in high-risk patients.
• Handover should include duration, stool frequency, blood, vomiting, dehydration category, fluids given, zinc, feeding, suspected cause, antimicrobial decision, malnutrition status, comorbid illness, outbreak risk, and follow-up plan.