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What is diarrhea?


Diarrhea is where you frequently pass watery or loose poo. Some people may also have other symptoms, depending on the cause.


It affects most people from time to time and is usually nothing to worry about. However, it can be distressing and unpleasant until it passes, which normally takes a few days to a week.

The excessive loss of water in your poo can also sometimes lead to symptoms of dehydration, which can be serious if it's not recognized and treated quickly.

When to seek medical advice for diarrhea

Contact your doctor for advice if you're concerned about yourself or your child.

You should also contact your doctor in the situations outlined below, as they may mean an increased risk of a more serious problem.


You should contact your doctor urgently if your baby has had six or more episodes of diarrhea in the past 24 hours, or if they've vomited three times or more in the past 24 hours.

You should also seek advice if your baby has any symptoms of dehydration.


Contact your doctor if your child has:

  • had six or more episodes of diarrhea in the past 24 hours
  • diarrhea and vomiting at the same time
  • watery poo
  • blood in their poo
  • a severe or continuous stomach ache
  • symptoms of dehydration

You should also contact your doctor if your child has persistent diarrhea. Most cases will pass in five to seven days.


Contact your doctor if you have diarrhea and:

  • there's blood in your poo
  • you're vomiting persistently
  • you've lost a lot of weight
  • you've passed a large amount of very watery diarrhea
  • it occurs at night and is disturbing your sleep
  • you've recently taken antibiotics or been treated in hospital
  • you have symptoms of dehydration
  • your poo is dark or black – this may be a sign of bleeding inside your stomach

You should also contact your doctor if you have persistent diarrhea. Most cases in adults will pass in two to four days.

Causes of diarrhea

There are many different causes of diarrhea, but a bowel infection (gastroenteritis) is a common cause in both adults and children.

Gastroenteritis can be caused by:

  • a virus – such as norovirus or rotavirus
  • bacteria – such as campylobacter or Escherichia coli (E. coli), which are often picked up from contaminated food
  • a parasite – such as the parasite that causes giardiasis, which is spread in contaminated water

These infections can sometimes be caught during travel abroad, particularly to areas with poor standards of public hygiene. This is known as traveler's diarrhea.

Diarrhea can also be the result of:

  • anxiety
  • a food allergy
  • medication
  • a long-term condition, such as irritable bowel syndrome (IBS)

Treating diarrhea

Most cases of diarrhea clear up after a few days without treatment, and you may not need to see your doctor.

However, diarrhea can lead to dehydration, so you should drink plenty of fluids until it passes.

It's very important that babies and small children don't become dehydrated. Your pharmacist may suggest you use an oral rehydration solution (ORS) if you or your child are particularly at risk of dehydration.

You should eat solid food as soon as you feel able to. If you're breastfeeding or bottle feeding your baby and they have diarrhea, you should try to feed them as normal.

Stay at home until at least 48 hours after the last episode of diarrhea to prevent spreading any infection to others.

Medications to reduce diarrhea, such as loperamide, are available. However, these aren't usually necessary, and most types shouldn't be given to children.

Preventing diarrhea

Diarrhea is often caused by an infection. You can reduce your risk by making sure you maintain high standards of hygiene.

For example, you should:

  • wash your hands thoroughly with soap and warm water after going to the toilet and before eating or preparing food
  • clean the toilet, including the handle and the seat, with disinfectant after each bout of diarrhea
  • avoid sharing towels, flannels, cutlery or utensils with others
  • wash soiled clothing and bed linen separately from other clothes and at the highest temperature possible – for example, 60C or higher for linen – after first removing any poo into the toilet
  • avoid returning to work or school until at least 48 hours after the last episode of diarrhea

Traveler's diarrhea

It's important to practise good food and water hygiene while travelling abroad, such as avoiding potentially unsafe tap water and undercooked food.

If you're planning a trip abroad, check health advice for the countries you'll be travelling to.

Read more about:

  • preventing food poisoning
  • travel vaccinations
  • food and water abroad

Rotavirus vaccination

Rotavirus is a virus that commonly causes diarrhea in children. A vaccine that helps protect children against rotavirus is now part of the routine childhood vaccination schedule.

This vaccine is given as a liquid that's dropped into a baby's mouth. It's given in two doses, with the first given at two months and another at three months.

Causes of diarrhea

Diarrhea usually occurs when fluid can't be absorbed from the contents of your bowel, or when extra fluid is secreted into your bowel, causing watery poo.

Short-term diarrhea

Diarrhea is usually a symptom of a bowel infection (gastroenteritis), which can be caused by:

  • a virus – such as norovirus or rotavirus
  • bacteria – such as campylobacter, Clostridium difficile (C. difficile), Escherichia coli (E. coli), salmonella or shigella; these can all cause food poisoning
  • parasites – such as the Giardia intestinalis parasite that causes giardiasis

Other possible causes of short-term diarrhea include:

  • feelings of anxiety
  • drinking too much alcohol
  • a food allergy
  • appendicitis
  • damage to the lining of the intestines as a result of radiotherapy


Diarrhea can also sometimes be a side effect of a medication, including:

  • antibiotics
  • antacid medicines that contain magnesium
  • some chemotherapy medicines
  • nonsteroidal anti-inflammatory drugs (NSAIDs)
  • selective serotonin reuptake inhibitors (SSRIs)
  • statins – cholesterol-lowering medicines
  • laxatives – medicine used to help empty your bowels

The patient information leaflet that comes with your medicine should state whether diarrhea is a possible side effect.

Long-term diarrhea

Conditions that can cause persistent diarrhea include:

  • irritable bowel syndrome (IBS) – a poorly understood condition that affects the normal functions of the bowel
  • inflammatory bowel disease – conditions that cause the gut to become inflamed, such as Crohn's disease and ulcerative colitis
  • celiac disease – a digestive condition where you have an adverse reaction to gluten
  • bile acid malabsorption – where bile produced by the liver builds up in the digestive system
  • chronic pancreatitis – inflammation of the pancreas
  • diverticular disease – where small bulges or pockets develop in the lining of the intestine
  • bowel cancer – this can cause diarrhea and blood in your stools

Persistent diarrhea can also sometimes occur after surgery on the stomach, such as a gastrectomy.

Diagnosing diarrhea

Most cases of diarrhea get better within a week, and you may not need to visit your doctor.

The information below explains what will happen if you need to see your doctor.

Identifying the cause

To identify what's causing your diarrhea, your doctor may ask you questions about:

  • what your stools are like – for example, if they're very watery or contain blood
  • how often you need to go to the toilet
  • whether you have other symptoms, such as a high temperature (fever)
  • whether you've been in contact with anyone else who has diarrhea, or have recently traveled abroad – this may mean you have picked up an infection
  • whether you have recently eaten out anywhere – this may mean you have food poisoning
  • whether you're taking medication and if it's recently changed
  • whether you've been stressed or anxious recently

Stool sample

Your doctor may ask you for a stool sample so it can be analyzed for signs of an infection if you have:

  • persistent diarrhea that's lasted more than two weeks
  • blood or pus in your stools
  • symptoms that affect your whole body, such as a fever or dehydration
  • a weakened immune system – for example, because you have HIV
  • recently traveled abroad
  • recently been in hospital or been taking antibiotics

Blood tests

Your doctor may suggest you have some blood tests if they suspect your diarrhea is being caused by an underlying health condition.

For example, your blood can be tested for signs of inflammation, which may suggest inflammatory bowel disease.

Rectal examination

Your doctor may recommend a digital rectal examination (DRE) if you have unexplained persistent diarrhea, particularly if you're over 50.

During a DRE, your doctor will insert a gloved finger into your bottom to feel for any abnormalities. It can be useful for diagnosing conditions that affect your rectum and bowel.

Further investigations

If you have persistent diarrhea and your doctor is unable to find the cause, they may refer you to your local hospital for further investigation.

You may have:

  • a sigmoidoscopy – a thin, flexible tube with a small camera and light on one (a sigmoidoscope) is inserted into your bottom and up into your bowel
  • a colonoscopy – a similar procedure that uses a larger tube called a colonoscope to examine your entire bowel

Treatment for diarrhea

Diarrhea usually clears up without treatment after a few days, particularly if it's caused by an infection.

In children, diarrhea usually passes within five to seven days and rarely lasts longer than two weeks.

In adults, diarrhea usually improves within two to four days, although some infections can last a week or more.

While waiting for your diarrhea to pass, you can ease your symptoms by following the advice outlined below.

Drink fluids

It's important to drink plenty of fluids to avoid dehydration , particularly if you're also vomiting. Take frequent small sips of water.

Ideally, adults should drink a lot of liquids that contain water, salt and sugar. Examples are soup broth or water mixed with juice.

If you're drinking enough fluid, your urine will be light yellow or almost clear.

It's also very important for babies and small children not to become dehydrated. Give your child frequent sips of water, even if they're vomiting. A small amount is better than nothing.

Fruit juice or fizzy drinks should be avoided as they can make diarrhea worse in children.

If you're breastfeeding or bottle-feeding your baby and they have diarrhea, you should continue to feed them as normal.

Contact your doctor immediately if you or your child develop any symptoms of dehydration.

Oral rehydration solutions

Your doctor or pharmacist may suggest using an oral rehydration solution (ORS) to prevent dehydration if you're at risk – for example, if you're frail or elderly. ORS can also be used to treat dehydration that has already occurred.

Rehydration solutions usually come in sachets. They are dissolved in water, and replace salt, glucose and other important minerals that are lost if you're dehydrated.


Your doctor or pharmacist may recommend giving your child an ORS if they're dehydrated or at risk of becoming dehydrated.

The usual recommendation is for your child to drink an ORS each time they have an episode of diarrhea. The amount they should drink will depend on their size and weight.

Your pharmacist can advise you about this. The manufacturer's instructions should also give information about the recommended dose.

You may be able to give your baby an ORS if they become dehydrated, but check with a doctor or pharmacist first.


Opinion is divided over when and what you should eat if you have diarrhea. However, most experts agree you should eat solid food as soon as you feel able to. Eat small, light meals and avoid fatty or spicy foods.

Good examples are potatoes, rice, bananas, soup and boiled vegetables. Salty foods help the most.

You don't need to eat if you've lost your appetite, but you should continue to drink fluids and eat as soon as you feel able to.


If your child is dehydrated, don't give them any solid food until they have drunk enough fluids. Once they stop showing signs of dehydration, they can start eating their normal diet.

If your child isn't dehydrated, offer them their normal diet. If they refuse to eat, continue to give them fluids and wait until their appetite returns.


Antidiarrheal medicines

Antidiarrheal medicines may help reduce your diarrhea and slightly shorten how long it lasts. However, they're not usually necessary.

Loperamide is the main antidiarrheal medicine used, as it has been shown to be effective and causes few side effects.

Loperamide slows down the muscle movements in your gut so more water is absorbed from your stools. This makes your stools firmer and they're passed less frequently.

An alternative to loperamide is a different type of antidiarrheal medicine called racecadotril, which works by reducing the amount of water produced by the small intestine.

Evidence suggests this medication may be as effective as loperamide for treating diarrhea.

Some antidiarrheal medicines can be bought from a pharmacy.

Check the patient information leaflet that comes with the medicine to find out whether it's suitable for you and what dose you should take. Ask your pharmacist for advice if you're unsure.

Don't take antidiarrheal medicines if there's blood or mucus in your stools or you have a high temperature (fever). Instead, you should contact a doctor for advice.

Most antidiarrheal medicines shouldn't be given to children. Racecadotril can be used in children over three months old if it's combined with oral rehydration and the other measures mentioned above, although not all doctors recommend it.


Painkillers won't treat diarrhea, but ibuprofen can help relieve a fever and a headache. If necessary, you can give your child liquid ibuprofen.

Always read the patient information leaflet that comes with the medication to check if it's suitable and find out the correct dose. Children under 16 years of age shouldn't be given aspirin.


Treatment with antibiotics isn't recommended for diarrhea if the cause is unknown. This is because antibiotics:

  • won't work if the diarrhea is caused by a virus
  • can cause unpleasant side effects
  • can become less effective at treating more serious conditions if they're repeatedly used to treat mild conditions

Antibiotics may be recommended if you have severe diarrhea and a specific type of bacteria has been identified as the cause.

They may also be used if you have an underlying health problem, such as a weakened immune system.

Hospital treatment

Occasionally, hospital treatment may be needed to treat serious dehydration. Treatment involves administering fluids and nutrients directly into a vein (intravenously).

Treating the underlying cause

If you've been diagnosed with a specific condition that's causing your diarrhea, treating this may help improve your symptoms.

For example:

  • irritable bowel syndrome (IBS) can be treated with changes to your diet and medications
  • inflammatory bowel disease can be treated with medications that help reduce inflammation in the bowel
  • celiac disease can be treated by excluding foods containing gluten from your diet
  • bile acid malabsorption can be treated with medication that helps stop bile building up in the digestive system


Probiotics are live bacteria and yeasts found in some yoghurts and food supplements.

There's some evidence that certain probiotics can slightly shorten a period of diarrhea, although the evidence isn't yet strong enough to recommend taking them.

There's also evidence to suggest some probiotics may reduce your chances of developing diarrhea after taking antibiotics.

Content supplied byNHS Logonhs.uk

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Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.

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