What Causes Diarrhoea?

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

Depending on the cause of diarrhoea, it can affect you for just a couple of days or for several weeks. Certain long-term health conditions and digestive problems mean that it can become an upsettingly regular feature of your life.

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.

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 poisoning
  • 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




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