Patient information from BMJ

Diarrhoea in adults

Last published:Mar 04, 2025

Diarrhoea is common and often clears up on its own after a few days. Most of the time it's nothing to worry about, but sometimes it can be a sign of a bigger issue. If you're feeling very ill, dehydrated, or your symptoms last too long, you may need to see a doctor.

This information covers diarrhoea in adults caused by a virus or bacteria. Some of the treatments we talk about aren't recommended for children. To learn more about diarrhoea in children, see our patient information titled: Diarrhoea in children.

What is diarrhoea?

If you have diarrhoea, your stools are loose and watery, and you need to go to the toilet more often than usual. 

There are many different causes of diarrhoea. This information covers diarrhoea that's caused by an infection with a virus or bacteria. You can get this type of infection in several ways, including:

• Contaminated food or drink: Consuming food or drink that contains harmful bacteria or viruses can cause diarrhoea. This often results from poor food hygiene or untreated water.

• Person-to-person contact: You can catch diarrhoea from someone who has it. This happens when you touch something that’s contaminated with traces of their stool (for example, the person’s hand) and then put your hand to your mouth (for example, when you eat).

• Contaminated surfaces: Objects like door handles or shared items can carry traces of a virus or bacteria from an infected person’s stool. Touching these surfaces and then your mouth can lead to infection.

People often get diarrhoea when they're travelling in other countries (called travellers' diarrhoea).

What are the symptoms of diarrhoea?

As well as watery stools, you may also get vomiting or stomach cramps. Because you lose water in your stools, having diarrhoea means your body may lose too much fluid (you get dehydrated). This makes you feel thirsty, and you might have dark-coloured urine, or feel sleepy.

If your diarrhoea doesn't clear up in a few days you should see a doctor. You should also see a doctor if:

• you have a high temperature (fever)

• there's blood in your stools

• you've been travelling abroad

• you've just come out of hospital

• you work as a carer, or

• you work in a job where you handle food.

If you're too ill to eat or drink, see a doctor as soon as you can.

What are the treatment options for diarrhoea?

Taking care of yourself

Some people prefer to eat simple foods, like bread, if they have diarrhoea. But the most important thing is to have plenty to drink.

It's best to avoid drinks that contain a lot of sugar as they can make diarrhoea worse. You should also avoid drinks that contain caffeine.

You can also go to a pharmacy and buy rehydration salts that you mix with water. They are designed to replace fluids and mineral salts your body may have lost. For people with mild dehydration, it's not clear whether they're better for rehydration than water or soft drinks.

Medicines

There are two main types of medicine that can help if you have diarrhoea: antibiotics to fight bacterial infection, and anti-diarrhoeals to slow down your bowel movements.

Antibiotics are drugs that kill bacteria. Not all diarrhoea is caused by bacteria, so antibiotics aren't the right treatment for everyone. Your doctor may do tests to see what kind of diarrhoea you have.

Antibiotics also have side effects. Some of these side effects may be similar to the symptoms you want treated, such as nausea, a stomach ache, or diarrhoea. But they aren't usually serious enough for people to stop taking their antibiotics.

Anti-diarrhoeals help to deal with diarrhoea by slowing down your bowel movements. You can buy these from a pharmacy. It's a good idea to pack some of this medicine whenever you go on holiday.

These medicines are a short-term solution for people with mild symptoms, or those recovering who need to travel.

They're not recommended for severe diarrhoea, as they can mask your symptoms. This means that, because they reduce your diarrhoea, you seem more recovered than you actually are.

Some of these medicines can cause side effects, including diziness and constipation.

You shouldn't take these medicines if you have a fever or if there's blood or mucus in your stools. If you have these symptoms, you should see a doctor.

What will happens next?

Diarrhoea isn't usually serious. Most people get better on their own without any problems.

The main risk is losing too much water (getting dehydrated). So it's important to drink plenty of fluids, especially if you're an older person. Drinking often, in small sips, may be the best way to drink with an upset stomach. Occasionally, people who get very dehydrated need to go to hospital.

Prevention

You can help prevent diarrhoea by washing your hands with soap after using the toilet, before preparing food, and before eating. If you’re travelling and washing your hands isn’t possible, you should try to use hand sanitiser.

There are other precautions you can take when travelling abroad, especially in countries where tap water might not be safe to drink.

When travelling in these countries you should only drink water that is bottled and properly sealed. Avoid eating or drinking:

• ice and tap water

• salads, previously peeled fruits, and raw foods

• unpackaged condiments and sauces

• food from street vendors and buffets.