Diarrhoea and food poisoning explained

What causes diarrhoea and food poisoning

Diarrhoea means passing loose or watery stools more often than usual. It is most commonly caused by a gut infection (gastroenteritis), which can be viral, bacterial, or occasionally from a parasite. Viruses such as norovirus and rotavirus spread easily from person to person and are a frequent cause, especially in winter and in places like schools and care homes. Food poisoning is diarrhoea and sickness caused by eating food contaminated with germs or their toxins, for example from undercooked meat, unpasteurised products, or food left too long at room temperature. Symptoms often include stomach cramps, nausea, vomiting, and sometimes a fever. Diarrhoea can also be triggered by some medicines, food intolerances, anxiety, or longer-term gut conditions, but a short bout is usually a passing infection.

Staying hydrated is the priority

The main risk from diarrhoea and vomiting is dehydration, especially in young children, older people, and anyone frail or unwell. The key to looking after yourself is to keep drinking small amounts of fluid often, even if you can only manage sips at a time. Water is fine, and for those at higher risk of dehydration, oral rehydration solutions from a pharmacy replace lost salts and sugars. Signs of dehydration include feeling very thirsty, a dry mouth, dark strong-smelling urine, passing little urine, tiredness, dizziness, and, in babies, fewer wet nappies and a sunken soft spot. Continuing to drink is more important than eating; appetite returns as you recover. A pharmacist can advise on rehydration and on caring for children safely at home.

Self-care and recovery

Most bouts of diarrhoea and food poisoning improve within a few days without any specific treatment, and often within about a week for diarrhoea. Rest, keep drinking, and eat when you feel able, starting with small, plain meals if that is easier; there is no need to avoid food once your appetite returns. Good hand washing with soap and water, especially after using the toilet and before handling food, helps stop the infection spreading to others; alcohol gels are less effective against some bugs such as norovirus. Anti-diarrhoea medicines are not usually needed and are not suitable for everyone, particularly children or if there is blood in the stools or a high fever; ask a pharmacist before using them. Clean and disinfect toilets and surfaces to limit spread within the household.

Staying off work or school

Because gut infections spread so easily, staying away from others while you are infectious protects them. NHS advice is to stay off work, school, or nursery until at least 48 hours after the last episode of diarrhoea or vomiting, and to avoid preparing food for other people during this time. It is also best to avoid swimming pools for two weeks after diarrhoea stops. People who handle food for a living, healthcare and care staff, and those caring for vulnerable people should be especially careful and may need to follow specific guidance from their workplace. Do not visit hospitals or care homes while you have symptoms, as infections like norovirus can be dangerous to vulnerable residents. These simple steps break the chain of spread.

When to seek medical help

Contact a GP or NHS 111 if diarrhoea lasts more than about seven days, or vomiting more than a couple of days, if you cannot keep any fluids down, or if you have signs of dehydration that do not improve with drinking. Seek advice for blood in your stools or vomit, severe or worsening tummy pain, a high fever, or if you have recently travelled abroad or been in hospital. People with weakened immune systems, and parents worried about a baby or young child, should seek help sooner, as dehydration develops faster in the very young. Phone 999 or go to A&E for signs of serious illness such as severe drowsiness, confusion, a stiff neck with a rash, difficulty breathing, or if someone becomes very weak and unresponsive.