16/08/2017 09:22 BST | Updated 16/08/2017 09:23 BST

A Guide To... Diarrhoea

Diarrhoea is passing stools more frequently or in a looser manner than is normal for you. It affects most people from time to time and is normally nothing to worry about, even if it is distressing or unpleasant. It occurs when fluid cannot be absorbed in the bowel or when extra fluid enters your stool, causing that stool to be watery when released.

What Causes it?

Diarrhoea can be caused by many different things including anxiety, excess alcohol intake, overuse of caffeine, lactose intolerance, appendicitis, food allergies and irritable bowel syndrome (IBS).

Many medications can also cause diarrhoea. These include antacids that contain magnesium, laxatives, digitalis, diuretics, antibiotics, chemotherapy drugs, cholesterol lowering agents, lithium, thyroxine, theophylline and colchicine. Radiotherapy given for abdominal or prostate cancers can also cause diarrhoea by damaging the intestine. There are also toxins produced by insecticides, mushrooms and arsenic that can cause diarrhoea.

When should you contact a GP?

Diarrhoea is normally nothing to be concerned about, but if you are concerned about a baby who has had six or more episodes of diarrhoea in the past 24 hours, you should contact your GP urgently.

For adults, diarrhoea is a concern if you are also noticing blood in your stool, your stool is black or tarry, you are vomiting persistently, you have lost a lot of weight or you have passed a large amount of watery diarrhoea.

You should also see a doctor if it occurs at night and is disturbing your sleep. Most cases of diarrhoea in adults should pass within 2-4 days.


During diarrhoea, it is important to stay hydrated with a lot of fluid as you are passing a lot of water with your stool. You should continue eating solid food if you feel able to. There are medications that reduce diarrhoea but these are not normally necessary in short-term cases of diarrhoea. Diarrhoea treatment is mainly about replacing lost fluid that also contains salts and sugars- these can be found in rehydration solutions or soups. Fruit juice or fizzy drinks can make diarrhoea worse.


Preventing diarrhoea is normally a case of reducing your risk of catching an infection. This includes making sure you maintain high standards of personal and food hygiene. You should make sure you wash your hands with soap and hot water after going to the toilet and both before and after eating/ preparing food.

After each bout of diarrhoea, you should clean the toilet and surrounding areas with a disinfectant, as well as making sure you are not sharing towels, flannels or cutlery with others. Any soiled linen or clothing should be washed separately at the highest temperature possible, and you should make sure not to attend school or work until 48 hours after the diarrhoea has passed.

When travelling abroad water hygiene is also important- this involves avoiding undercooked food and making sure the tap water you're drinking is safe. If in doubt, try and choose bottled water over fresh water.

Your doctor may wish for a sample of your stool to send to a laboratory for testing. If they suspect a food allergy or intolerance, they may ask you to stop eating that food and record if it relieves the diarrhoea. If your doctor needs more information they may arrange for you to have a colonoscopy, which is where a thin tube with a camera inside is inserted into your rectum and used to view the entire colon.

Dr Seth Rankin is founder of London Doctors Clinic