What is diarrhoea?

Diarrhoea is the repeated and frequent passing of abnormally loose or watery stool. Most of the time, you’ll contract diarrhoea as a result of food poisoning or from coming into contact with someone who is already suffering from it.

Harmful microorganisms work their way into your digestive system, causing you to develop a bowel infection (gastroenteritis).

What causes Diarrhoea?

Diarrhoea can be embarrassing and disabling. The primary symptoms— frequent, loose and often watery stools — may temporarily prevent you from getting on with your everyday life.

But there are other symptoms too, which you may or may not experience, depending on the cause of your illness:

  • Stomach pain
  • Wind and bloating
  • Fatigue and tiredness
  • Nausea and/or vomiting
  • Incontinence

While things like stomach cramps and diarrhoea are common, there are some rather more colourful symptoms, too. You may notice green diarrhoea, for example. Your stools can turn green in colour due to food poisoning, fast-moving bile or resulting from use of laxatives.

What causes diarrhoea in these cases? Nasty microorganisms work their way into your digestive system, causing you to develop a bowel infection (gastroenteritis). These include:

  • Bacteria (such as E.coli, Salmonella or Shigella)
  • Viruses (such as a norovirus, rotavirus or enterovirus)
  • Parasites (such as those which cause giardiasis and amoebiasis)

The underlying cause of your diarrhoea is an indicator of how severe it will be and how long it will last. Getting the runs from norovirus means your symptoms will probably disappear after a couple of days, whereas giardiasis can cause diarrhoea which lasts for weeks.

It’s also possible to develop diarrhoea in response to allergies, stress or taking certain medicines. Other causes of non-infectious diarrhoea include:

  • Food intolerances, including lactose and gluten intolerance
  • Flare-ups in inflammatory bowel diseases, such as Crohn’s disease
  • Irritable bowel syndrome (IBS)
  • Appendicitis
  • Pancreatic problems
  • Recent surgery on the stomach and intestines, or removal of the gallbladder
  • Hormonal changes, for example those linked to thyroid disease, adrenal disease and diabetes
  • Bowel cancer and rare tumours
  • Radiotherapy to the abdomen
  • Overuse of caffeine or alcohol

Diarrhoea after eating

Sometimes diarrhoea is triggered while you’re eating, or shortly after you’ve finished a meal, particularly if you’re already suffering from an upset tummy as the bowel and the nerves that control its behaviour are already irritated. As the stomach and small intestine stretch with food, the nerve reflexes which trigger your need to go to the toilet are more easily stimulated.

Painful and persistent diarrhoea

Some symptoms are less common and might be a sign of something more serious. If you’ve had persistent diarrhoea for more than three or four days, or notice any of the following symptoms, then it’s recommended you get in touch with your GP immediately:

  • Blood in your stool or dark black stools
  • Mucus passed with no stools
  • Severe pain in your abdomen or rectum
  • Fever
  • Dehydration

In these more serious cases, your doctor will probably need to take a stool sample and send it off for testing.

How to manage diarrhoea

Working out how to stop diarrhoea isn’t always straightforward. Acute diarrhoea, which appears suddenly, often resolves itself with some simple steps after a few days. Chronic diarrhoea may take longer to treat.

When you have diarrhoea, it’s important to keep hydrated, drink plenty of fluids in small, regular sips. Opt for liquids that contain lots of water, salt and sugar, such as thin soup and fruit juice mixed with water. You can also take oral rehydration solution drinks if you already feel very dehydrated.

Although you might not feel like it, it’s recommended that you eat solid food as soon as you can. Stick to light and fairly bland snacks such as bananas, vegetables and potatoes, rather than deep fried foods and spicy curries.

Wondering how to prevent diarrhoea so that it doesn’t happen again?

You can bolster your defences against the viruses and bacteria that cause diarrhoea by trying to improve your general digestive health. A healthy balanced diet, rich in fibre containing foods such as wholegrain carbohydrates and a wide variety of vegetables and fruit can help achieve an optimally balanced gut. However, if you are unable to tolerate these foods, an easy way to add fibre to your diet is through a high fibre food supplement.


Please seek advise from your GP or healthcare practitioner if you are suffering from chronic diarrhoea, especially if it gets worse.

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