Food nutrients are absorbed in the small intestine. The waste is pushed into the large intestine (bowel) where water is removed. The resulting faeces is stored temporarily within the rectum then passed out of the body through the anus. Faeces are usually firm, moist and easy to pass. Diarrhoea is the frequent passing of loose, watery and unformed faeces.
Acute diarrhoea is the sudden onset of three or more loose stools per day, lasting less than 14 days. The most common cause of acute diarrhoea is an infection of the intestines, such as gastroenteritis or food poisoning. Viruses are responsible for most cases. The intestinal lining becomes irritated and inflamed, which hinders the absorption of water from food waste. In severe cases, the intestinal lining may even leak water.
Generally, acute diarrhoea resolves after a day or two. Chronic diarrhoea, which lasts four weeks or more, can be caused by a range of conditions that affect the intestines, including inflammatory bowel disease (IBD).
Symptoms of diarrhoea
The symptoms associated with diarrhoea include:
- abdominal cramps
- abdominal pains
- urgency to go to the toilet
- frequent passing of loose, watery faeces
Serious symptoms of diarrhoea
In most cases, acute diarrhoea is self-limiting and will resolve by itself within a day or two.
However, contact your doctor immediately if you experience serious symptoms including:
- blood in the faeces
- pus in the faeces
- painful passage of faeces
- repeated vomiting
- inability to increase fluid intake
- reduced or absent urination
- fever (temperature greater than 38 ºc).
If you have a serious chronic medical condition, such as kidney or heart failure, even one day of diarrhoea can be dangerous. It’s safer to see your doctor as soon as possible.
Diarrhoea can be dangerous for babies and young children
Acute diarrhoea can be life threatening to babies and young children. This is because their smaller bodies are more vulnerable to dehydration. If your baby or young child develops diarrhoea, seek medical attention straight away.
Causes of acute diarrhoea
A bout of diarrhoea can be caused by a wide range of disorders, infections and events including:
- food poisoning
- tropical diseases, such as typhoid and cholera
- anxiety or emotional stress
- overconsumption of alcohol
- medications, particularly antibiotics.
Common infectious agents
Contaminated food and water are common causes of acute diarrhoea. Some of the infectious agents known to cause diarrhoea include:
- viruses – such as calici virus, adenovirus and rotavirus
- bacteria – such as E. coli, Campylobacter, V. cholerae, Shigella, Salmonella and Staphylococcus aureus
- parasites – such as Giardia lamblia, Cryptosporidium parvum and tapeworm.
Causes of chronic diarrhoea
- Some of the causes of chronic diarrhoea include:
- coeliac disease – which reduces the intestine’s ability to absorb food
- chronic constipation – the bowel is blocked by hard, impacted faeces, but some liquids manage to seep past the blockage. this condition, called ‘spurious’ or ‘overflow’ diarrhoea, is more common in the elderly
- hormone disorders – such as diabetes or hyperthyroidism (overactive thyroid gland)
- cancer – such as bowel cancer
- inflammatory bowel disease – including ulcerative colitis and Crohn’s disease
- irritable bowel syndrome – symptoms include abdominal pain, bloating, and alternating constipation and diarrhoea
- lactose intolerance – the inability to digest the milk sugar lactose
- medications – including antibiotics, antacids that contain magnesium, laxatives, and drugs for treating hypertension (high blood pressure) and arthritis.
Diagnosis of diarrhoea
Successful treatment depends on diagnosing the cause. Investigations may include:
- medical history
- physical examination
- blood tests
- laboratory analysis of stool sample
- colonoscopy (the insertion of a slender instrument into the anus so that the doctor can look at the bowel lining).
Treatment for diarrhoea
Always see your doctor if you experience serious symptoms. Babies and young children with diarrhoea need prompt medical attention.
Treatment for diarrhoea depends on the cause, but may include:
- plenty of fluids to prevent dehydration
- oral rehydration drinks to replace lost salts and minerals. These drinks are available from pharmacies. An alternative is one part unsweetened pure fruit juice diluted with four parts of water
- intravenous replacement of fluids in severe cases
- medications such as antibiotics and anti-nausea drugs
- anti-diarrhoeal medications, but only on the advice of your doctor. If your diarrhoea is caused by infection, anti-diarrhoeal drugs may keep the infection inside your body for longer
- treatment for any underlying condition, such as inflammatory bowel disease.
Risk of spreading infection
Most cases of acute diarrhoea are potentially infectious to others. Viruses are easily spread, mainly through direct contact with vomit or faeces from an infected person, or through contact with a contaminated object or surface. Occasionally, the virus may be transmitted by airborne particles generated from vomiting and diarrhoea.
People can reduce their chances of getting infected by carefully washing their hands after going to the toilet and before handling food. People looking after a person with the virus must also wash their hands thoroughly. Alcohol-based handwash solutions, available from pharmacies, have been shown to be better at reducing the spread of infection than soap and water, and are less drying to the skin.
Anyone with acute diarrhoea should stay at home if possible to reduce the spread of infection. It is strongly recommended not to visit hospitals and nursing homes, and not to swim in public pools.
Dietary adjustments may help diarrhoea
It may help to make a few short-term dietary adjustments while your bowels recover from acute diarrhoea.
Be guided by your healthcare professional, but general suggestions include:
- Limit consumption of fatty, sweet or spicy foods.
- Avoid alcohol.
- Increase consumption of starchy foods like banana, rice and bread.
- Increase consumption of yoghurt containing live cultures.
- Diarrhoea in babies and young children can be caused by fruit juice, so limit these drinks.
Where to get help
- Your doctor
- NURSE-ON-CALL Tel. 1300 60 60 24 – for expert health information and advice (24 hours, 7 days)
Things to remember
- Diarrhoea is the frequent passing of loose, watery faeces.
- In most cases, acute diarrhoea is self-limiting and resolves after a day or two.
- Acute diarrhoea in babies and young children can be life threatening due to the risks of dehydration.
This page has been produced in consultation with and approved by:
Canberra Hospital - Gastroenterology Unit
Page content currently being reviewed.
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