Synopsis
Recognise viral gastroenteritis, correct dehydration safely, distinguish dangerous mimics and interrupt norovirus transmission across healthcare and community settings.
- Norovirus commonly causes abrupt vomiting, watery diarrhoea and rapid spread; fever is usually low grade and illness is often short.
- Assess hydration from physiology and urine output, not from stool frequency alone; older adults may present with falls, confusion or acute kidney injury.
- Oral rehydration is preferred when tolerated; shock requires prompt isotonic intravenous crystalloid with reassessment after every bolus.
- Do not prescribe antibiotics for a compatible uncomplicated viral syndrome because they neither shorten nor prevent norovirus infection.
- Isolate symptomatic inpatients promptly, use soap-and-water hand hygiene and apply the organisation's virucidal environmental-cleaning policy.
- Exclude symptomatic healthcare and food-handling staff until at least 48 hours after vomiting and diarrhoea have stopped.
- Send stool testing when severe disease, diagnostic uncertainty, prolonged symptoms, immune compromise or outbreak control makes the result actionable.
- Escalate bloody stool, focal abdominal signs, persistent fever or deterioration because viral gastroenteritis may be the wrong diagnosis.
Key red flags
Persistent hypotension, mottling, confusion or oliguria indicates severe hypovolaemia or sepsis.
Bloody diarrhoea, peritonism or pain out of proportion suggests invasive infection, ischaemia or another surgical process.
Recent antibiotics or healthcare exposure increases the probability of Clostridioides difficile infection.
Marked immune compromise, frailty or major comorbidity lowers the threshold for admission and microbiological investigation.
An institutional cluster of sudden vomiting or diarrhoea requires immediate isolation and outbreak escalation.
Tachycardia, postural or persistent hypotension, dry mucosa, delayed capillary refill, reduced urine output and acute confusion indicate clinically important volume depletion.
Two or more epidemiologically linked cases of unexplained vomiting or diarrhoea in a ward, care home, school or food setting should trigger outbreak procedures.
Blood, sustained high fever, focal tenderness, peritonism, toxic appearance, prolonged diarrhoea or severe pain should widen the differential immediately.
Frailty, pregnancy, renal or cardiac disease and immune suppression increase dehydration risk and may blunt fever or abdominal symptoms.
Investigation priorities
Determine immediate resuscitation, admission and escalation needs before seeking an organism.
Management branches
Vomiting or diarrhoea has produced clinically important dehydration or circulatory compromise.
- Use ABCDE, measure glucose and urine output, establish access and identify cardiac or renal conditions that change fluid tolerance.
- Offer correctly prepared oral rehydration in frequent small volumes when the airway is safe and perfusion is adequate.
- For hypovolaemic shock, give a 500 mL bolus of crystalloid containing sodium 130 to 154 mmol/L over less than 15 minutes, then reassess immediately.
- Repeat laboratory tests and fluid-balance review according to severity; seek senior or critical-care input if perfusion does not promptly improve.