Acute Gastroenteritis

Medically reviewed by Joel Nyandigira Updated August 2026

Overview


Acute gastroenteritis is a sudden inflammation of the stomach and intestines, most often caused by viral or bacterial infection, resulting in diarrhoea and often vomiting. It is especially common and potentially serious in young children due to the risk of dehydration.

Symptoms of Acute Gastroenteritis


  • Watery diarrhoea, typically several episodes over 24 hours
  • Nausea and vomiting
  • Abdominal cramps
  • Mild fever in some cases
  • Signs of dehydration to watch for: reduced urination, dry mouth, sunken eyes, lethargy, or, in infants, a sunken soft spot on the head

What Causes Acute Gastroenteritis?


  • Most commonly caused by viruses, particularly rotavirus in young children, and norovirus in older children and adults.
  • Bacterial causes (such as E. coli or Salmonella) and, less commonly, parasites can also cause acute gastroenteritis.
  • Spread through the faecal-oral route via contaminated food, water, or contact with an infected person, and easily transmitted in households and childcare settings.

How is Acute Gastroenteritis Diagnosed?


  • Mainly a clinical diagnosis based on the pattern of diarrhoea and vomiting.
  • Assessment for signs of dehydration — using skin turgor, mucous membranes, alertness, and, in infants, the fontanelle — is the most important part of evaluation and guides treatment.
  • Stool testing is generally reserved for prolonged illness, blood in the stool, or outbreak investigation.

Treatment for Acute Gastroenteritis


Oral rehydration solution is the cornerstone of treatment for all cases, given in small, frequent amounts, alongside continued feeding (including continued breastfeeding in infants) as tolerated.

Zinc supplementation is given to children under five, as it reduces the duration and severity of the illness and future episodes.

Antibiotics are not needed for most cases of acute gastroenteritis, as the majority are viral; they are reserved for specific bacterial causes or severe presentations as determined by a health worker.

Antidiarrhoeal medicines that slow gut motility are generally avoided, particularly in young children.

Children or adults with signs of moderate to severe dehydration, persistent vomiting preventing oral intake, or high fever are referred for further assessment and may need intravenous fluids.

How to Prevent Acute Gastroenteritis


  • Drink water from safe sources, or boil or treat water before drinking.
  • Wash hands with soap after using the toilet and before preparing or eating food.
  • Support rotavirus vaccination as part of the routine childhood immunisation schedule.
  • Continue breastfeeding during illness in infants, as it supports both hydration and nutrition.
  • Practise safe food handling and storage to reduce contamination risk.
1 Source

Mfamasia's health articles are based on evidence-backed information and review by medical professionals to ensure accuracy, reliability and up-to-date health standards.

  1. Tanzania Standard Treatment Guidelines (STG) and National Essential Medicines List (NEMLIT), Ministry of Health, Community Development, Gender, Elderly and Children, United Republic of Tanzania, 2021 Edition.