Video: Diarrhoea

What is diarrhoea?

Diarrhoea is a very common digestive complaint that will affect most people at some time in their lives. It can involve frequent, urgent, loose and watery bowel movements, often with cramp-like pain in and bloating of the abdomen.

Signs and symptoms

If you have diarrhoea, you can have sudden, watery, loose or runny stools often accompanied by the following:

  • Abdominal bloating and cramp-like pain;
  • Loss of appetite;
  • Constant urge to use the toilet, and;
  • Tiredness.

Diarrhoea can be acute (less than 14 days) or chronic (longer-term). Seek medical attention if severe diarrhoea lasts for more than 12 hours, or if you experience the following symptoms:

  • High fever;
  • Blood, undigested food and mucus in your stool;
  • Nausea and constant vomiting, and;
  • Inability to pass urine, feeling weak and dizzy (signs of dehydration). 

Abdominal cramps with bloating and diarrhoea, runny stools, bloating and nausea, traveller's diarrhoea, urgent bowel movement.

Diarrhoea causes abdominal bloating and pain.


Diarrhoea is a symptom of an underlying bowel disturbance, which can be caused by numerous factors. As most episodes are acute and tend to pass within a few days, the cause may never be known. With infectious agents such as bacteria or viruses, the invading germs cause the lining of the intestines to become inflamed. This inflammation stops water from being absorbed, causes watery stools and can prevent proper digestion of food. 

Infectious agents


Viruses can often become widespread in places where people are in close contact with each other. Nursing homes, schools and offices are often centres of diarrhoea outbreaks. Hepatitis A, Cytomegalovirus and Rotavirus are all implicated. The main cause of childhood diarrhoea is Rotavirus, whereas Norovirus affects all ages.


Bacteria can find their way into your body via contaminated food or drinks that have been handled by unwashed hands. You may experience fever, vomiting, blood in the diarrhoea and severe pain in your abdomen. Common bacterial infections are:

  • Escherichia coli (E. coli)  -  the different types of E. coli bacteria are the most common cause of traveller’s diarrhoea, caused by faecal matter contaminating drinking water as a result of poor sanitation, and;
  • Salmonella, Shigella, Staphylococcus aureus, Vibrio cholerae and Campylobacter bacteria are also common bacteria that can lead to diarrhoea.


Parasites are usually ingested via contaminated drinking water. The most common culprits are Cryptosporidium, Entamoeba histolytica and Giardia lamblia.


Diarrhoea can be a side effect of many medications including antibiotics, anti-cancer medications, magnesium-containing antacids, statins (medications used to lower cholesterol) and medications for blood pressure, weight loss, anti-HIV and arthritis. Broad-spectrum antibiotics are associated with Clostridium difficile, a bacteria that infects your intestines when antibiotics have removed your normal gut bacteria.

Food intolerance 

If you have intolerance to foods such as spicy foods, fruit sugars (fructose), some artifical sweeteners and dairy products (lactose intolerance), you may develop diarrhoea.

Chronic disease or disorders of your intestines

There are several conditions that may increase your risk of chronic diarrhoea, such as Crohn’s disease, ulcerative colitis, coeliac disease, pancreatitis, cystic fibrosis, irritable bowel syndrome, diverticulitis and ischaemic colitis.


Bowel resection surgery, gall bladder surgery (cholecystectomy) and abdominal surgeries all may leave you prone to developing diarrhoea.


Bowel cancer may cause chronic diarrhoea.

Hormone disorders

Conditions such as hyperthyroidism and diabetes can affect the bowels and cause diarrhoea.

Other causes

Competitive running, alcohol abuse, too much coffee, too much vitamin C and emotional stress or anxiety can all affect your bowels.

Risk factors

You are more likely to get diarrhoea if you are in one of the following groups of people:

  • If you have been diagnosed with a condition such as diabetes, inflammatory bowel disease, chronic pancreatitis or cystic fibrosis;
  • If you have a weakened immune system;
  • If you take medications such as antacids, antibiotics or antidepressants;
  • If you travel to developing parts of the world such as South-East Asia, Africa, Latin America and the Middle East, or are living in poor sanitary conditions, and;
  • If you live with someone who currently has diarrhoea – many types are highly infectious and can be easily spread.


There are a number of reasons you may experience diarrhoea. Quite often it is a result of food poisoning, a bacterial or viral infection, side effects of a medication, food intolerance, parasites, or a disease of the gastrointestinal tract. Infectious gastroenteritis (stomach flu) can also cause fever and vomiting and is the most common cause of diarrhoea. Traveller's diarrhoea is also a common problem for visitors to developing countries. The following are the most common types of diarrhoea:

Osmotic diarrhoea

Osmotic diarrhoea occurs when too much water is drawn into the bowels, often by poor digestion or substances your body cannot absorb. Digestive conditions such as coeliac disease or lactose intolerance can cause this type of diarrhoea. Some types of laxatives, vitamin C, excessive magnesium and chewing gum containing sorbitol can also cause osmotic diarrhoea. Once you stop ingesting these products, the diarrhoea will usually clear up quickly.

Inflammatory diarrhoea

This type of diarrhoea is caused by inflammation in your bowel and can be caused by a wide range of factors; inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis, or infections caused by bacteria, parasites or viruses can cause inflammatory diarrhoea. Though much less common, bowel cancer and tuberculosis can also cause inflammatory diarrhoea.

Motility-related diarrhoea

This type of diarrhoea is caused by food moving through your digestive system too quickly and not being absorbed properly. This can be due to a physical or nerve-related issue. If you have been diagnosed with an overactive thyroid gland (hyperthyroidism), diabetes, have undergone bowel surgery, or have fistulas (abnormal connections within your intestines), you may have motility-related diarrhoea.

Exudative diarrhoea

This type of diarrhoea may contain both blood and pus. It is often seen with inflammatory bowel disease, or caused by an infection such as Shigella.

Secretory diarrhoea

This type of acute diarrhoea is often caused by infection with bacteria such Vibrio cholerae or E. coli that results in overstimulation of mucus secretions in your bowel.

Methods for diagnosis

If you have acute diarrhoea, it will normally resolve or significantly improve within 12 hours. If it lasts longer and if you have other symptoms such as severe pain or blood in your stool, you may wish to visit your doctor. There are a range of tests and procedures available to diagnose what is causing your diarrhoea.

Medical history

Your doctor will ask about your symptoms, recent travel, if you have you been eating out, any recent illnesses, your medications and your family history.

Physical examination

Your doctor may check to see if you have abdominal bloating or pain. Physical examination can reveal if you are dehydrated. If your diarrhoea is chronic and ongoing, you may be given a digital rectal examination (DRE) to check if there are any physical problems within your rectum. This involves your doctor inserting a gloved finger into your anus to check for lumps or any abnormalities.

Blood and stool tests

These tests can check your blood for any underlying health conditions or inflammation. Stool microscopy, culture and sensitivity will be done to check if you have any parasites or unusual bacteria in your stool. 

Intolerance testing

Your doctor may suggest tests for food intolerance, or ask you to stop eating certain foods to see if your symptoms improve.


In some circumstances, the internal lining of your bowel may need to be examined using endoscopy. This can be particularly useful in chronic (prolonged) diarrhoea, or diarrhoea of a possibly serious or unknown cause. An endoscopy involves inserting an endoscope into the intestines, either via the mouth (gastroscopy) or rectum (colonoscopy). You may be given a mild sedative to help you relax during the procedure and often will be asked not to eat for 12 hours prior to the test. The endoscope can take videos and photos and give your doctor a highly-detailed view of the bowels, helping to locate areas of inflammation or tumours. A biopsy can also be carried out by endoscopy to aid in the diagnosis of conditions such as coeliac disease and Crohn’s disease, and identify the presence of any tumours.

Types of treatment

Most cases of diarrhoea will clear up at home without much treatment. The most important issue though, is to avoid dehydration, especially in young children and babies. Untreated diarrhoea can be life-threatening for young ones, being the biggest cause of death in this age group in developing nations.

Home care

Drinking increased amounts of clear fluids such as water, juice, cordial and broth and avoiding tea, coffee, alcohol, dairy products and spicy and greasy foods will improve the diarrhoea symptoms. As diarrhoea can cause weakness, bed rest is recommended. Oral rehydration solutions are a good way to keep up your fluid, salt and sugar levels and can be bought from your pharmacist. Once the diarrhoea stops, try eating starchy foods such as rice, bananas, dry toast and potatoes. On the third day, try small amounts of yoghurt containing live bacterial cultures and grilled or steamed meat.


Drugs called anti-motility medications stop diarrhoea by slowing down your intestinal movement (peristalsis). These are useful for socially-embarrassing diarrhoea, but if you are being treated for a bacterial or parasitic infection, they can make it worse. Always speak to your doctor before taking any medication to stop diarrhoea.


Antibiotics will only work if you have been diagnosed with a particular bacteria. Antibiotics will not help if your diarrhoea is caused by a virus and may, in fact, make it worse.

Hospital treatment

This is only for serious or complicated cases. Young children, or those at a risk of dehydration may be hospitalised. Rehydration is normally done via an intravenous (IV) drip.

Treating the underlying cause

If you have an inflammatory bowel disease, food intolerance or another medical condition, this needs to be addressed. Your doctor may recommend you see a specialist.

Potential complications

The main complications of diarrhoea come from dehydration, which can quickly become life-threatening in the elderly, those with a weakened immune system and particularly small children and babies. If your child becomes weak, dizzy, passes less urine, has fast and deep breathing and sunken eyes, this calls for immediate medical attention. If you are over 60 years of age, or have a cardiovascular condition such as heart disease or a history of stroke, or if you are being treated with chemotherapy, you can become seriously ill after only a few hours of diarrhoea. Other complications may include:

  • Malnutrition - which leads to weakness;
  • Dehydration  -  watch for sunken eyes, lack of energy, dizziness, dry skin and a lack of tears or urine in children;
  • Anaemia - symptoms include a pale and exhausted appearance;
  • Electrolyte imbalance - this can result in dizziness, muscle spasms or cramps and fatigue, and; 
  • Haemolytic uremic syndrome (HUS) caused by E. coli  -  this is a very rare condition that affects young children. If your child has blood in their diarrhoea, seek medical attention immediately.


Diarrhoea usually tends to improve within a few days without any treatment, or once the underlying cause is removed or treated. Have plenty of rest and keep hydrated while you are recovering. Stay away from swimming pools, nursing homes, schools or any other heavily-populated places for 48 hours after you have recovered. If your diarrhoea is caused by an infectious agent, the following timescales for recovery usually apply:

  • Norovirus – between 3-8 days;
  • Rotavirus – about two days;
  • Giardiasis – about two weeks, and;
  • Salmonella, Campylobacter – between 2-7 days.


There are many simple day-to-day measures you can take to reduce your chance of getting diarrhoea, including the following:

  • Always wash your hands after using the toilet, touching animals, handling food (especially meat), changing nappies, sneezing/coughing, or touching doors or furniture in public toilets; 
  • Teach small children to wash their hands after going to the toilet and to avoid putting things in their mouths;
  • Use a hand sanitiser if you cannot wash your hands;
  • Take care to refrigerate foods after cooking and properly reheat food. Always cover dishes to avoid contact from flies or pets, and;
  • Always keep your kitchen and food preparation areas clean. Be careful not to cross-contaminate other foods with raw meat or unpasteurised products.

Wash hands after using toilet, wash hands before cooking, wash hands after handling food, wash hands after changing nappies.

Handwashing can significantly reduce spreading of diarrhoea-causing infections.

When travelling, the following measures will reduce your chances of developing diarrhoea:

  • Only drink from sealed bottles or cans, do not use ice in drinks and brush your teeth using bottled water;
  • Only eat well-cooked foods. Avoid salads, pre-cut fruit and vegetables and any foods that have been left on benches. Avoid dairy foods unless they are refrigerated and produced by recognised brands. The general rule 'boil it, cook it, peel it or forget it' may be useful, and; 
  • Get vaccinated – children can be protected from Rotavirus by receiving an oral vaccination.