Diarrhoea (US spelling: diarrhea) is a symptom where there is excessively frequent bowel movements with the passage of loose or watery stool. The strict definition of diarrhoea is passing stool more than 3 times in a 24 hour period and/or passing more than 200g/200mL of stool within 24 hours. However, most people use the term diarrhoea to describe any abnormality of bowel habit where stool is passed more frequently than normal, is watery or less firm and solid than usual. Most people refer to diarrhoea as runny tummy or a running stomach.


There are several different types of diarrhoea, categorised according to the nature of the underlying problem.

  1. Osmotic diarrhoea where there are excessive solutes that remain in the bowel and the body cannot absorb this water to form solid stool.
  2. Secretory diarrhoea where a large amount of water is drawn out from the body into the bowels and cannot be reabsorbed fast enough.
  3. Inflammatory diarrhoea where the lining of the bowel is irritated and inflamed thereby affecting the water absorption from the bowels. It can occur due to inflammation caused by the immune system like in inflammatory bowel disease (IBD) or microorganisms including viruses, bacteria or protozoa. It is also known as infectious diarrhoea when microbes are the cause.
  4. Diarrhoea due to deranged bowel motility where the movement through the bowels are faster than normal affecting nutrients and water from being properly absorbed due to the rapid bowel transit time.


Normally food and fluid move slowly through the bowels where it is digested and nutrients absorbed. A large amount of water is pushed out into the bowels to aid with digestion but it is reabsorbed back into the body within the colon. The liquid intestinal chyme is then transformed into solid waste material that is known as stool or faeces. However, in diarrhoea one or more processes are disturbed. Either water is not fully absorbed, excessive amounts of water are pumped into the bowels or the movement through the bowels are abnormally fast.

The most common cause of acute diarrhoea is an infection of the stomach and bowels. This is known as gastroenteritis. The virus, bacteria or protozoan (single-celled parasite) either directly attack the bowel lining or releases toxins which injure it. Sometimes the toxins are present in food or drinks even though there are no microbes. Once these contaminated foods or drinks are consumed, it can inflame the bowel lining and cause diarrhoea. The action of these toxins on its own in contaminated food and fluid is known as food poisoning.

There are a host of other causes that may not be due to an infection. Some of these include:

  • Chronic diarrhea is seen in conditions like inflammatory bowel disease (IBD) where the immune system erroneously attacks the bowels and causes inflammation.
  • Food intolerances like lactose intolerance are caused by the body’s inability to digest specific foods. Sometimes the body is unable to absorb nutrients which are known as malabsorption syndromes and can lead to diarrhoea.
  • Irritable bowel syndrome (IBS) is another condition that presents with diarrhoea usually as a result of the bowel motility being abnormally rapid due to overactivity of the nerves that control movement through the bowels.


Diarrhoea is not a disease but a symptom. Apart from the abnormality in bowel habit, most people also experience an uncontrollable urge to pass stool and feel that they did not have a complete bowel movement afterwards. It can be seen in many different diseases and is commonly accompanied by other symptoms such as:

  • Nausea and vomiting
  • Abdominal cramps
  • Bloating
  • Flatulence
  • Burning of the anus

Some people experience constipation alternating with diarrhoea in conditions like inflammatory bowel disease and irritable bowel syndrome.


Diarrhoea can be a very serious symptom and even life threatening. It remains one of the most common causes of infant death across the globe. Diarrhoea itself is usually not fatal but rather the cause and complications may be deadly. Dehydration is the main complication that needs to be prevented as the body can lose large amounts of water and electrolytes through diarrhoeal stool. Most cases of acute diarrhoea will resolve on its own within a few days and not need any medical treatment. However, severe diarrhoea, bloody stool and the signs of dehydration needs prompt medical attention.


Antidiarrhoeal medication like loperamide may be used in persistent diarrhoea but should not be the first line of treatment. Diarrhoea is a way for the body to flush out harmful microorganisms and its toxins which may thrive and do extensive damage to the bowels. The choice of treatment depends on the cause of the diarrhoea. For example, antibiotics may be required for bacterial and protozoal infections while immune-modulating drugs may be used in inflammatory bowel disease.


It is important for a person to maintain sufficient hydration while experiencing diarrhoea. This can be done orally with rehydrating solutions that are available over-the-counter at all pharmacies. These sachets contain specific electrolytes in the optimal combination which can be added to clean water and drank throughout the day until the diarrhoea resolves. If dehydration has set in then rehydration may need to be done through an intravenous (IV) drip. Energy drinks, milk and cooldrinks should be avoided as it can sometimes worsen diarrhoea.

Natural Remedies

Herbal remedies should be used cautiously in diarrhoea as it can irritate the already inflamed bowels. Homeopathic remedies may be a better option but the choice of remedy may vary depending on the cause and nature of the diarrhoea. Arsenicum album and Podophyllum are two common homeopathic remedies prescribed by homeopaths for diarrhoea. Always consult with a registered homeopath about your diarrhoea and other symptoms in order to be prescribed the most effective and rapidly acting remedies for diarrhoea, be it acute or chronic.


Most people opt to avoid solid food for a few hours to a day after diarrhoea starts. A liquid diet should not be sustained in the long term as it can lead to malnutrition. A person should return to a normal diet as soon as possible if there is no vomiting. A simpler transition from liquid to solids would involve first adopting the BRAT diet (mashed bananas, plain rice, grated apple, toast without butter) and then switching to balanced but bland meals within thereafter.


Probiotics can be very helpful in restoring the ‘good’ bowel bacteria (normal intestinal flora) which becomes disturbed in diarrhoea. However, diary may not be the best option, not even live culture yoghurt. Most people develop what is known as secondary lactose tolerance and eating live culture yoghurt after acute diarrhoea can worsen the problem. Instead capsules containing the correct blend of microbial spores should be taken for up to 5 days. It can be purchased at most pharmacies and will restore the bacterial populations in the bowel. Live culture yoghurt can then be consumed in the long term to restore the balance of these different bacteria.