Diarrhoea in adults

What is diarrhoea?

If you have diarrhoea, you have loose, watery stools. You also need to go to the toilet more often than normal.

This information looks at diarrhoea that's caused by an infection with a virus or bacteria. You pick these up from contaminated food or water. You can also catch diarrhoea from another person 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).

People often get diarrhoea when they're travelling in other countries. It's a good idea to pack diarrhoea medicine whenever you go on holiday.

What are the symptoms?

As well as watery stools, you may also get vomiting or stomach cramps. Because you lose water in your stools, your body may not have enough fluid (you get dehydrated). This makes you feel thirsty, 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 temperature, 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 treatments work?

You can help prevent diarrhoea by washing your hands after using the toilet, before preparing food and before eating.

Some people prefer to eat simple foods, like bread, if they have diarrhoea. But we don't know if being careful about what you eat helps you get better any faster. The most important thing is to have plenty to drink. Water or soft drinks are fine. You can also go to a chemist and buy rehydration salts that you mix with water. They are designed to replace fluids and mineral salts your body may have lost. But there hasn't been any research to tell us whether they're better than drinking water on its own, or soft drinks.

Medicines can help diarrhoea by slowing down your bowel movements. They include loperamide (brand name Imodium) and co-phenotrope (Lomotil).

You can buy loperamide from a chemist. You can also buy co-phenotrope over the counter as long as you're over 16.

In studies, some people who took loperamide were better after a day. This compared with two days for people who didn't take it. Taking co-phenotrope may mean you don't need to go to the toilet as often. But it didn't help people's diarrhoea clear up any faster.

You may get constipated if you take loperamide. In one of the studies, 25 in 100 people taking loperamide got constipation, compared with 7 in 100 people who didn't take it. Some people also get dizziness, drowsiness or a dry mouth.

The research on co-phenotrope didn't mention side effects. But if you take it regularly, you can get unpleasant withdrawal symptoms when you stop taking it.

You shouldn't take loperamide or co-phenotrope if you have a temperature, or if there's blood or mucus in your stools. If you have these symptoms, see a doctor.

Antibiotics are drugs that kill bacteria. But 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.

Several studies show that antibiotics can help you recover more quickly from diarrhoea caused by bacteria. They can also help with a temperature. One study found that taking antibiotics with loperamide works faster than taking antibiotics on their own.

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

A chemical called bismuth is sometimes used to treat diarrhoea. The brand name is Pepto-Bismol. You can buy it from a chemist. Bismuth is a liquid that's designed to coat the inside of your bowels and kill bacteria. It may help some people who get diarrhoea when they're travelling, but there's not much research.

There's a small chance that bismuth will cause your tongue to change colour, or you may get black stools. These side effects go away when you stop taking the drug. Don't take bismuth if you're allergic to aspirin or if you're pregnant.

What will happen to me?

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 elderly. Drinking often, in small sips, may help. Occasionally, people who get very dehydrated need to go to hospital.