When diarrhoea needs medical review
Red flags, sepsis risk, and high-risk situations
Why this matters
Most diarrhoea settles without medical intervention. Serious complications occur when dehydration, infection, or sepsis is missed — particularly in vulnerable people.
Seek urgent medical care now if any of the following are present
Stool features
- Blood in stool (red or maroon)
- Black or tarry stool
- Profuse watery diarrhoea causing rapid dehydration
Systemic symptoms
- Fever ≥38.5°C (101.5°F)
- Severe or worsening abdominal pain
- Persistent vomiting preventing fluid intake
- Confusion, drowsiness, collapse, or fainting
Signs of dehydration
- Little or no urine output
- Dark, concentrated urine
- Marked thirst with dry mouth
- Dizziness on standing
- Lethargy or irritability (especially in children)
High-risk groups (lower threshold for care)
Seek medical advice earlier if diarrhoea occurs in infants/young children, over 65, pregnancy, immunosuppression, asplenia, chronic kidney/heart/liver disease.
Sepsis risk and diarrhoea
Diarrhoea can be the presenting symptom of sepsis, particularly with invasive infections.
- Rapid heart rate
- Low blood pressure
- Rapid breathing
- Confusion or altered mental state
- Cold, mottled, or clammy skin
If sepsis is suspected, seek emergency care immediately.
Duration-based guidance
| Duration | What it suggests | What to do |
|---|---|---|
| <3 days | Usually viral or toxin-mediated | Focus on hydration |
| 3–7 days | Infection possible | Review if not improving |
| 7–14 days | Persistent diarrhoea | Stool testing advised |
| ≥4 weeks | Chronic diarrhoea | Structured evaluation needed |
Special scenarios requiring caution
Recent antibiotics or hospital stay
- Risk of C. diff
- Avoid anti-diarrhoeal agents
- Seek testing early
Bloody diarrhoea in children
Consider STEC and risk of haemolytic uraemic syndrome (HUS).
Recent travel
Fever + diarrhoea after travel warrants assessment; typhoid and cholera are rare but serious.
When hospital admission is likely
- Moderate to severe dehydration
- Inability to maintain oral intake
- Severe electrolyte disturbance
- Suspected sepsis
- Complications such as HUS or acute kidney injury
Key takeaway: Early assessment saves lives. Delaying care is far riskier than seeking help unnecessarily.