Why does food poisoning cause diarrhoea?

Diarrhoea is a very common presentation of Food Poisoning. An irritated intestinal lining may not absorb water as usual, while the bowel pushes its contents forward more quickly. This produces frequent, loose or watery stools and may occur alongside cramps, nausea, vomiting or fever.

Diarrhoea has many causes, including infections not linked to food, medicines and digestive conditions. The timing of symptoms, recent meals, travel and whether other people are ill can give useful clues, but do not replace a medical assessment when symptoms are concerning.

The immediate aim is to replace fluids and salts. Sip water or an oral rehydration drink often; small amounts may be easier if you feel nauseated. Eat light foods as appetite returns and pause foods or drinks that aggravate symptoms. Rest, use separate towels where possible and wash hands with soap after using the toilet and before handling food. Ask a pharmacist before taking anti-diarrhoea medicine, especially if you have fever or blood in the stool.

Seek urgent care if there is blood or black stool, severe abdominal pain, repeated vomiting, marked drowsiness, confusion, fainting, or dehydration such as dizziness and passing very little urine. Contact a clinician if diarrhoea persists, returns frequently, or you are pregnant, immunocompromised, an older adult or caring for a young child. Medical advice is also sensible after travel or recent antibiotic treatment.

Explain when diarrhoea started, how often stools are occurring, whether you can keep fluids down and whether anyone who ate the same food has symptoms. Ask what rehydration plan suits you and whether testing is needed.