How common is blood in stool in gastroenteritis?

Gastroenteritis is irritation or inflammation of the stomach and intestines, often caused by an infection. When the bowel lining is inflamed, stools may become loose and may contain blood or mucus. Nausea, vomiting, cramps, fever and an urgent need to pass stool can occur at the same time. Blood alone cannot show which germ, if any, is responsible, and it does not rule out non-infectious causes.

Focus on fluids if you can drink, using small frequent sips when nausea makes larger drinks difficult. Seek medical advice for bloody diarrhoea, ongoing symptoms, fever, or if you are pregnant, older, immunocompromised, or caring for a young child. A clinician may ask about recent food, travel, contact with others who are unwell, antibiotics and medicines. Avoid using anti-diarrhoea medicines unless a healthcare professional says they are suitable.

Urgent assessment is needed for severe dehydration, confusion, fainting, severe or worsening abdominal pain, a rigid abdomen, high fever, repeated vomiting that prevents drinking, black tar-like stool, or a substantial amount of blood. Rapid changes in alertness or breathing also need emergency care.

Ask whether stool testing is appropriate, how to recognise dehydration, what you should drink or eat while recovering, and when it is safe to return to work or school. Tell your clinician about recent antibiotic use, medical conditions that affect immunity, and any household members with similar symptoms.