What happens in the digestive system when you have diarrhea

Diarrhoea will usually clear up without treatment after a few days, particularly if it's caused by an infection.

In children, diarrhoea will usually pass within 5 to 7 days and will rarely last longer than 2 weeks.

In adults, diarrhoea usually improves within 2 to 4 days, although some infections can last a week or more.

While waiting for your diarrhoea 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 small, frequent sips of water.

Ideally, adults should drink a lot of liquids that contain water, salt, and sugar. Examples are water mixed with juice and soup broth. 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 are vomiting. A small amount is better than none. 

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

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

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

Oral rehydration solutions

Your GP 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 available from your local pharmacist without a prescription. They are dissolved in water and replace salt, glucose, and other important minerals that are lost if you are dehydrated.

Children

Your GP or pharmacist may recommend giving your child an ORS if they are 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 diarrhoea. 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 your GP, pharmacist, or health visitor first.

Eating

Opinion is divided over when and what you should eat if you have diarrhoea. 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.

Children

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

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

Medication

Antidiarrhoeal medicines

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

Loperamide is the main antidiarrhoeal 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 antidiarrhoeal 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 diarrhoea.

Some antidiarrhoeal medicines can be bought from a pharmacy without a prescription. 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.

Do not take antidiarrhoeal medicines if there is blood or mucus in your stools or you have a high temperature (fever). Instead, you should contact your GP for advice.

Most antidiarrhoeal medicines should not be given to children. Racecadotril can be used in children over 3 months old if it's combined with oral rehydration and the other measures mentioned above, although not all doctors recommend it.

Painkillers

Painkillers will not treat diarrhoea, but paracetamol or ibuprofen can help relieve a fever and a headache. If necessary, you can give your child liquid paracetamol or ibuprofen.

Always read the patient information leaflet that comes with the medication to check if it's suitable for you or your child and find out the correct dose. Children under 16 years of age should not be given aspirin.

Antibiotics

Treatment with antibiotics is not recommended for diarrhoea if the cause is unknown. This is because antibiotics:

• will not work if the diarrhoea 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 diarrhoea 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 if you or your child are seriously dehydrated. Treatment will involve 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 diarrhoea, treating this may help improve your symptoms.

For example:

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

Read more about common causes of diarrhoea.

What happens to digestive system during diarrhea?

Does diarrhea clean out the digestive system?

How does diarrhea affect the organ system?

What organ is affected by diarrhea?