This factsheet is about acute diarrhoea

Most healthy people open their bowels between three times a day and three times a week. Normal stools are usually solid because the small intestine and colon are highly efficient in absorbing nutrients, fluid and salts from the gut contents.

Diarrhoea occurs when these processes are impaired, for example when bacteria or viruses damage the lining of the gut and/or there is excessive secretion of fluid, such as water, into the bowel that overwhelms the ability of the gut to reabsorb this fluid and salts. The stools become loose and watery and more frequent bowel movements occur. In acute diarrhoea, symptoms come on suddenly but usually clear up within five to 10 days.


Causes of acute diarrhoea

There are many reasons why acute diarrhoea can occur. Common causes include:

  • Intestinal infection (gastroenteritis): this is the most common cause of acute diarrhoea with infants and young children particularly susceptible. Bouts of norovirus diarrhoea often make the news since they can occur in local epidemics.
  • Food poisoning: another common form of acute diarrhoea usually caused by the Salmonella and Campylobacter bacteria. These infections can be passed via contaminated water or food, such as poultry and eggs, or by a carrier (i.e. someone who has the infection but no symptoms).
  • Medications: acute diarrhoea can sometimes occur during or after a course of antibiotics or as a result of other medications which cause the contents of the bowel to move too rapidly through the gut resulting in insufficient time for absorption. It is always worth asking your doctor whether your medications can cause diarrhoea. Laxatives can result in an excessive secretion of fluid into the bowel.
  • Anxiety: as with some medications, anxiety can cause the bowel contents to move too rapidly through the gut.
  • Irritable Bowel Syndrome (IBS): bowel frequency is sometimes increased in those suffering from IBS. However, there is no increase in stool volume, which distinguishes it from acute diarrhoea, where stool volume is increased.


What are the usual symptoms of acute diarrhoea?

Acute intestinal infections are commonly associated with cramping pain in the central or lower abdomen. Some infections may cause fever, particularly infections due to Shigella and Campylobacter that get into the lining of the bowel and cause acute inflammation. When there is direct damage to the bowel, blood may be associated with the diarrhoea, which is known as dysentery. Nausea and vomiting often occur and put sufferers off their food.

How is acute diarrhoea diagnosed?

Most episodes of Acute Diarrhoea get better without the need for specific medical advice. However if you are a food handler then you should always consult your doctor and inform your employer. Otherwise you should seek medical advice if any of the following apply:

  • If diarrhoea persists for more than 14 days
  • If you notice blood in the diarrhoea
  • If you develop a high fever
  • If your cramping and abdominal pains become severe and constant

The doctor will want to talk to you about your symptoms to try to identify a cause. The doctor will also want to physically examine your abdomen and possibly your back passage. The priority at this stage is to ensure that your stool is checked to determine whether there are any infective agents present that might be the cause of the diarrhoea and your other symptoms.


How is acute diarrhoea treated?  

Most episodes of acute diarrhoea will settle within a few days without any intervention. However, if the episode is severe there are several treatments that can help.

Rehydration: ensure that enough additional fluids and salts are taken to replace those lost in the diarrhoea. For infants, young children and the elderly, who are more sensitive to fluid losses, it is wise to use a pre-prepared oral rehydration solution, which can be purchased over the counter in most pharmacies. For most adults, oral rehydration can usually be achieved simply by increasing fluid intake in the form of mineral water, fruit juices (which also contain potassium) and salty soups (sodium), together with some form of carbohydrate (rice, pasta, salty crackers), which is important for promoting fluid and salt absorption.

Food intake: there is no need to stop eating although sufferers often prefer a lighter diet in the early phase of the illness. There is no need to interrupt breast-feeding for breast-fed infants. Bottle-fed infants should still receive full-strength formula milk. In general for adults, avoid dairy products and spicy foods until other foods are well tolerated.

Medication: an anti-diarrhoea drug such as loperamide is available from pharmacies without prescription. This is often helpful early in the illness to reduce bowel frequency. However, it should not be used in infants and very young children because of concerns that is may depress respiration.

Antibiotics: for travellers with severe diarrhoea for whom the loss of one or two days would seriously affect their activities, the severity and duration of the illness can be dramatically reduced by taking a short course, or even a single dose of broad spectrum antibiotic.

Can acute diarrhoea be avoided?

One of the most important and basic ways to avoid it is by careful handwashing after using the bathroom and before consuming food. Because most acute diarrhoea is related to intestinal infection that is usually transmitted by contaminated food or water, then it is possible to avoid an illness by being scrupulously careful about food and fluid intake. Only drink bottled or boiled water and avoid ice cubes when the origin of the water is uncertain. Avoid raw, unpeeled fruits and salads, shellfish and all foods that might contain raw egg. The safest food is that which is hot and well cooked. Bouts of diarrhoea due to norovirus occur in local epidemics, and it is important not to spread infection, so avoid visiting hospitals and unwell relatives at such times.

Can acute diarrhoea be prevented?

Hygiene measures as outlined above should always be the first line protection against acute diarrhoea. However there are some other measures that may help to reduce the chances of being affected.

Antibiotics: for those travelling to high-risk areas (such as Indian sub-continent, South East Asia, Africa and Latin America) the chance of experiencing an attack of acute diarrhoea can be reduced by taking a broad spectrum antibiotic. However, this is not generally advised because antibiotics do have adverse effects and widespread use in this way can lead to the emergence of antibiotic resistance. There is a danger, therefore, that the treatment might be worse than the disease.

Vaccines:  vaccines for traveller’s diarrhoea are under development and one moderately effective vaccine is now available in the United Kingdom (Dukoral). It is aimed at a type of bacteria known as enterotoxigenic Escherichia coli (E.coli), which is the most common cause of traveller’s diarrhoea.

Probiotics: there is some evidence that probiotics (such as lactobacilli and bifidobacteria) found in ‘live yoghurts’ and other preparations may also reduce the chances of experiencing an episode of infective diarrhoea. In addition, over the counter medications may also be useful and your pharmacist can advise you.


Does acute diarrhoea need to be monitored and if so, how?

Most episodes will settle spontaneously without the need for any medical treatment. However if it persists, you may also be referred for an endoscopy, where a flexible tube with a camera is passed into the bowel via the anus, to determine whether there is any inflammation in the rectum or colon (colitis). In addition, if your stool tests show any sign of infection this may be treated with antibiotics or further investigations.

What to ask your doctor?

  • Could my diarrhoea be caused by any medications I am currently taking and, if so, is there an alternative?
  • Are there any over the counter treatments I can take?
  • Do I need my stools checked?
  • Do I need to be monitored further?