Conditions & Investigations



Diarrhoea is defined as the passage of more than 3 loose or liquid stools per day. Some definitions also include the amount of stool that one passes which is about 200g per day.

Diarrhoea is usually split into 2 types – acute or chronic. Whilst there is no definition on the duration of symptoms that characterize acute rather than chronic, it is generally accepted that diarrhoea lasting for over 4 weeks is usually chronic.

Most causes of acute diarrhoea are due to an infection – many of these infections are usually self limiting and viral in nature and do not require antibiotics.

There are many causes of chronic diarrhoea:

  • Irritable bowel syndrome – one of the commonest causes of chronic diarrhoea. IBS can cause crampy abdominal pain and changes in bowel habit which could be constipation, diarrhoea or even a combination of the two.
  • Inflammatory bowel disease – there are several types of inflammatory bowel diseases – two of the most common are ulcerative colitis and Crohn’s disease.
  • Bowel cancer – a change in bowel habit and developing diarrhoea could be a symptom of bowel cancer.
  • Infections that cause chronic diarrhoea can be found in people who travel or live in tropical or developing countries which develop after eating contaminated food or drinking contaminated water. One of the commonest world wide causes of chronic diarrhoea is Giardiasis
  • Endocrine disorders – an overactive thyroid gland (a gland found in your neck which produces the hormone thyroxine) can cause chronic diarrhoea and weight loss. This can be detected with a simple blood test. Diabetes can also cause diarrhoea, as over time, the nerves that supply the digestive tract can become injured.
  • Food allergies such as lactose intolerance can cause diarrhoea. People with Coeliac disease, which is an allergy to gluten, which is found in wheat flour, commonly causes diarrhoea
  • Medication – medication, both prescription only and over the counter medicines, herbs and dietary supplements can cause diarrhoea as a side effect. If a medicine could be the cause of diarrhoea, it is important to review the list of medication that you are taking with your doctor or pharmacist before deciding to stop any medicine.

You should seek medical attention if you have loose stools that last more than three or four weeks. You may need to be seen sooner than this if you have complications of diarrhoea (such as blood in the stool, fever, feel dehydrated or lose weight) or have tummy pain that interferes with your normal every day activities or prevents you from eating normally.