Diarrhoea and dysentery: what should you know?

Dysentery is a description of bloody or mucus-filled diarrhoea, not a single diagnosis. Infection from contaminated food or water is one possibility, including food poisoning, gastroenteritis or giardiasis. Inflammation in the bowel can also cause blood, urgency and cramping; conditions such as Crohn's disease or coeliac disease may be considered according to the wider pattern. Food intolerance and irritable bowel syndrome can cause loose stools, but visible blood should not be assumed to come from them. The amount and colour of blood, pain, fever and recent travel are useful details.

Contact a healthcare professional promptly if you see blood or mucus in diarrhoea. Until assessed, take frequent sips of safe fluids and use oral rehydration solution if advised. Eat small, plain meals when able. Wash hands thoroughly, clean shared toilet surfaces and avoid preparing food for other people. Do not use leftover antibiotics or anti-diarrhoeal medicines without medical advice when blood is present, as they may be unsuitable for the cause.

Go to urgent care for heavy bleeding, black stools, severe or worsening abdominal pain, a swollen abdomen, fainting, confusion, repeated vomiting or very little urine. Fever with bloody diarrhoea also warrants prompt assessment. Children, older adults and people with weakened immunity can become dehydrated quickly. A clinician may examine you and request stool testing to guide treatment and reduce spread.

Could this be an infection or bowel inflammation? Do I need stool testing? Which fluids and medicines are safe while blood is present? How should I protect people at home?