Diarrhoea

Overview

Diarrhoea is when you pass loose, watery poo more often than usual. It usually lasts a few days and gets better on its own.

Yes, diarrhoea is very common. Most adults will have it once or twice a year, and children even more often.

Anyone can get diarrhoea, but it is most common in young children, older adults, and people with weakened immune systems.

Symptoms

Common symptoms

• Loose, watery poo
• Feeling an urgent need to go to the toilet
• Stomach cramps or pain
• Feeling sick (nausea) or vomiting
• Feeling bloated

Symptoms in children

• Fussiness or crying more than usual
• Dry mouth or crying without tears
• Sunken eyes or soft spot on the head
• Fewer wet nappies than usual (less than 4 in 24 hours)
• Pee that is dark yellow or smells strong

Symptoms in older adults

• Feeling weak or dizzy
• Confusion or trouble thinking clearly
• Dry mouth and sticky lips
• Not needing to pee as often as usual
• Fast heartbeat or feeling faint when standing

Causes

Main causes

• Viral infections – like norovirus or rotavirus
• Bacterial infections – from contaminated food or water (food poisoning)
• Parasites – tiny organisms that infect the gut
• Food intolerances – trouble digesting certain foods, like lactose in milk
• Medicines – especially antibiotics, which can upset the balance of germs in the gut
• Digestive conditions – such as irritable bowel syndrome (IBS) or Crohn’s disease

Risk factors

• Recent travel to areas with poor water or food hygiene (traveller's diarrhoea)
• Eating undercooked meat or unwashed vegetables
• Drinking untreated water from streams or lakes
• Living with or caring for someone with diarrhoea
• Having a weakened immune system (for example, from chemotherapy or HIV)

When to see a doctor

See a doctor urgently if:

• You have any of the emergency signs (severe pain, blood in poo, high fever, severe dehydration)
• Diarrhoea in a baby under 6 months old
• A child with diarrhoea who cannot keep fluids down
• An older adult who becomes confused or very weak

Book a routine appointment if:

• Diarrhoea that lasts longer than 1 week
• Diarrhoea that keeps coming back
• You have recently taken antibiotics or been in hospital
• You have lost weight without trying
• You have a chronic condition like IBS or diabetes

Diagnosis

A doctor will ask about your symptoms, recent travel, and any foods you may have eaten. They will listen to your belly and check for signs of dehydration.

Tests that may be done

• Stool test – a sample of your poo is sent to a lab to look for infection
• Blood test – to check for infection or dehydration
• Lactose or other food tolerance tests – if a food intolerance is suspected

What to expect at your appointment

The visit usually takes 15–20 minutes. The doctor may ask you to describe your poo and how often you go. You may need to provide a stool sample. Most people do not need any tests if diarrhoea is short-lived.

Treatment

Treatment focuses on preventing dehydration and letting the body fight off the cause. Most diarrhoea improves in 3–5 days with simple self-care.

Self-care at home

• Drink plenty of clear fluids – water, clear broth, or oral rehydration solution (made from powder at a pharmacy)
• Avoid dairy, caffeine, alcohol, and very spicy or fatty foods until diarrhoea stops
• Eat plain, easy-to-digest foods when you feel hungry – like rice, bananas, or plain toast
• Rest as much as possible
• Wash your hands after using the toilet to stop the spread

Medical treatments

Doctors may recommend oral rehydration salts to replace lost water and salts. For some bacterial infections, short-term antibiotics are prescribed. If a parasite is found, anti-parasitic medicines can be given. For chronic conditions like IBS, treatment targets the underlying cause. Always check with a doctor or pharmacist before taking any medicine for diarrhoea, especially if you have a long-term condition.

When is surgery considered?

Surgery is not used to treat diarrhoea itself. If a serious condition like an abscess or blockage in the gut causes diarrhoea, surgery may be needed, but this is rare.

Living with this condition

If you have chronic diarrhoea (lasting weeks or longer), keep a diary of what you eat and when symptoms happen. Plan your day so you know where toilets are. Carry a small bag with wipes and a change of clothes.

Lifestyle tips

• Wash your hands regularly, especially after touching food or using the bathroom
• Avoid sharing towels, cutlery, or cups when you have symptoms
• Cook food thoroughly and store leftovers safely

Diet and exercise

Stick to bland foods like plain rice, boiled potatoes, and bananas when symptoms flare. Gradually add back fibre-rich foods like oats and cooked vegetables. Gentle exercise like walking can help digestion, but rest more when you feel unwell.

Mental health and emotional wellbeing

Diarrhoea can be embarrassing and stressful. It may make you feel anxious about going out or meeting people. It is normal to feel frustrated or low. Talk to your doctor if these feelings do not improve.

Prevention

Many cases can be prevented with simple hygiene – wash hands after using the toilet, before eating, and after changing nappies. Cook food properly, drink clean water, and wash fruits and vegetables.

Vaccines

There is a vaccine for rotavirus, a common cause of severe diarrhoea in young children. It is given as drops by mouth as part of routine childhood immunisations in many countries, including the UK.

Screening programmes

There is no routine screening for diarrhoea. If you have long-term diarrhoea, your doctor may recommend a colonoscopy (a camera test inside the bowel) to check for conditions like chronic bowel disease.

Complications

If left untreated

• Dehydration – the most common complication, especially dangerous for young children and older adults
• Electrolyte imbalance – loss of important minerals like sodium and potassium, affecting heart and muscle function
• Malnutrition – if diarrhoea lasts a long time, the body may not absorb enough nutrients

Long-term outlook

For most people, diarrhoea gets better completely with no lasting problems. Even cases that last longer can be managed well with medical help. Severe dehydration is rare if you drink enough fluids and see a doctor when needed.

Find support

International organisations

• World Health Organization (WHO) ↗
• UNICEF – Diarrhoea and Children ↗

Local organisations

• NHS – Diarrhoea and Vomiting ↗ · United Kingdom
• Guts UK Charity ↗ · United Kingdom

Helplines

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