August 23, 2020

Diarrhoea: An Overview of Acute Diarrhoeal Disease

Diarrheal disease is one of the top ten leading causes of death worldwide and a particular concern for children younger than five years old in resource-limited settings. Among adults in resource-rich settings, diarrhea is often a "nuisance disease" in the healthy individual. Diarrhoea can be of sudden onset lasting less than two weeks (acute) or more than two weeks (persistent or chronic). In most cases, diarrhoea eases and resolves within few days though sometimes it takes longer. The main risk is dehydration. The main treatment is drinking lots of fluid to avoid dehydration. You should also eat as normally as possible. See a doctor if you suspect that you are dehydrating, or if you have any worrying symptoms as listed below. This article deals with acute diarrhoea, which is common.

What is diarrhoea?

Diarrhoea is defined as the passage of three or more loose or liquid stools per day (or more frequent passage than is normal for the individual) or the passage of more than 250 g of unformed stool per day. Frequent passing of formed stools is not diarrhoea, nor is the passing of loose, "pasty" stools by breastfed babies.

Diarrhoea is usually a symptom of an infection in the intestinal tract, which can be caused by a variety of bacterial, viral and parasitic organisms. Infection is spread through contaminated food or drinking-water, or from person-to-person as a result of poor hygiene.

There are three clinical types of diarrhoea:
  • acute watery diarrhoea – lasts several hours or days, and includes cholera;
  • acute bloody diarrhoea – also called dysentery or invasive diarrhoea; and
  • persistent diarrhoea – lasts 14 days or longer.
On the basis of its duration, diarrhea can be classified as acute (less then 14 days), persistent (14 to 29 days), or chronic (30 or more days).

Key facts about diarrhoea

Data from the WHO summarizes important key facts:
  • Diarrhoeal disease is one of the top ten leading causes of death worldwide.
  • Diarrheal disease is the second leading cause of death in children under five years old.
  • Diarrhoea is both preventable and treatable.
  • Each year diarrhoea kills around 525 000 under-5 children worldwide.
  • A significant proportion of diarrhoeal disease can be prevented through safe drinking-water and adequate sanitation and hygiene.
  • Globally, there are nearly 1.7 billion cases of childhood diarrhoeal disease every year.
  • Diarrhoea is a leading cause of malnutrition in children under five years old.

What causes acute diarrhoea?

Infection of the gut is the common cause. This is of sudden onset and is called acute infectious diarrhoea:
  • Gastroenteritis. Many bacteria, viruses and other germs can cause diarrhoea. Sometimes the germs come from infected food (food poisoning). Infected water is a cause in some countries. Sometimes it is just 'one of those germs going about'.
  • Viruses are easily spread from one person to another by close contact, or when an infected person prepares food for others.
  • Examples of infectious diarrhoea include norovirus, Clostridium difficile, Escherichia coli, campylobacter, salmonella and cryptosporidium.
Other causes are uncommon and include drinking lots of beer, side-effect of some medicines and anxiety.

Gut disorders that cause persistent or chronic diarrhoea may be mistaken for acute diarrhoea when they first begin - for example, diarrhoea caused by ulcerative colitis.

This article deals with infectious causes of acute diarrhoea.

When should I seek medical advice?

Seek medical advice in any of the following situations, or if any other symptoms occur that you are concerned about:
  • If you suspect that you are loosing too much fluid from your body (getting dehydrated).
  • If you are vomiting a lot and unable to keep fluids down.
  • If you have blood in your diarrhoea or vomit.
  • If you have severe tummy (abdominal) pain.
  • If you have severe symptoms, or if you feel that your condition is becoming worse.
  • If you have a persisting high temperature (fever).
  • If your symptoms are not settling - for example, vomiting for more than 1-2 days, or diarrhoea that does not start to settle after 3-4 days.
  • Infections caught abroad (outside the country).
  • If you are elderly or have an underlying health problem such as diabetes, epilepsy, inflammatory bowel disease, kidney disease.
  • If you have a weakened immune system because of, for example, chemotherapy treatment, long-term steroid treatment, HIV infection.
  • If you are pregnant.

What are the symptoms of acute infectious diarrhoea?

The main symptom is diarrhoea (see definition above), often accompanied with vomiting. Blood or mucus can appear in the stools with some infections.

Crampy pains in your tummy (abdomen) are common. Pains may ease for a while each time you pass some diarrhoea.

A high temperature (fever), headache and aching limbs sometimes occur.

If vomiting occurs, it often lasts only a day or so but sometimes longer. Diarrhoea often continues after the vomiting stops and commonly lasts for several days or more. Slightly loose stools may persist for a week or so further before a normal pattern returns. Sometimes the symptoms last longer.

Symptoms of lack of fluid in the body (dehydration)

The most severe threat posed by diarrhoea is dehydration. Diarrhoea and vomiting may cause dehydration and they need rapid medical attention. Severe dehydration is more common in babies and is a medical emergency.

During a diarrhoeal episode, water and electrolytes (sodium, chloride, potassium and bicarbonate) are lost through liquid stools, vomit, sweat, urine and breathing. Dehydration occurs when these losses are not replaced.

The degree of dehydration is rated on a scale of three.
  • Severe dehydration (at least two of the following signs):
    • lethargy/unconsciousness
    • sunken eyes
    • unable to drink or drink poorly
    • skin pinch goes back very slowly ( ≥2 seconds )
  • Some dehydration (two or more of the following signs):
    • restlessness, irritability
    • sunken eyes
    • drinks eagerly, thirsty
  • No dehydration (not enough signs to classify as some or severe dehydration).

Do I need any tests?

Most people with acute infectious diarrhoea do not need to see a doctor or seek medical advice. Symptoms are often quite mild and commonly get better within a few days without any medical treatment i.e. the disease is mostly self-limited.

However, in some circumstances, you may need to see a doctor (see above about when to seek medical advice). The doctor may ask you various questions - for example, about:
  • Recent travel abroad.
  • Whether you have been in contact with someone with similar symptoms.
  • Whether you have recently taken antibiotics.
  • Whether you have recently been admitted to hospital.
This is to look for possible causes of your diarrhoea. The doctor will also usually examine you, especially looking for signs of dehydration.

Tests are not usually needed. However, if you are particularly unwell, have blood in your faeces, have recently travelled abroad, are admitted to hospital, or your symptoms are not getting better, your doctor may ask you to collect a stool sample. This can then be examined in the laboratory to look for the cause of the infection.

What is the treatment for infectious diarrhoea in adults?

Symptoms often settle within a few days or so as your immune system usually clears the infection. Occasionally, admission to hospital is needed if symptoms are severe, or if complications develop (see below).

The following are commonly advised until symptoms ease.

Fluids - have lots to drink

The aim is to prevent dehydration, or to treat dehydration if it has developed. (Note: if you suspect that you are dehydrated, you should contact a doctor.)
  • As a rough guide, drink at least 200 mls after each bout of diarrhoea (after each watery stool (faeces)).
  • This extra fluid is in addition to what you would normally drink. For example, an adult will normally drink about two litres a day but more in hot countries. The above advice of 200 mls after each bout of diarrhoea is in addition to this usual amount that you would drink.
  • If you have vomited, wait 5-10 minutes and then start drinking again but more slowly. For example, a sip every 2-3 minutes but making sure that your total intake is as described above.
  • You will need to drink even more if you are dehydrated. A doctor will advise on how much to drink if you are dehydrated.
For most adults, fluids drunk to keep hydrated should mainly be water. It is best not to have drinks that contain a lot of sugar, such as cola or pop, as they can sometimes make diarrhoea worse.

Rehydration drinks (oral rehydration salt solution, ORS) are recommended for people who are frail, or over the age of 60, or who have underlying health problems. They are made from sachets that you can buy from pharmacies. (The sachets are also available on prescription.) Simply add contents of the sachet to water. ORS provides a good balance of water, salts and sugar. They do not stop or reduce diarrhoea. However, the small amount of sugar and salt helps the water to be absorbed better from the gut into the body. Home-made salt/sugar mixtures are used in developing countries if rehydration drinks are not available but they have to be made carefully, as too much salt can be dangerous. Rehydration drinks are cheap and readily available, and are the best treatment.

Anti-secretory medicines are designed to be used with rehydration treatment. They reduce the amount of water that is released into the gut during an episode of diarrhoea. They can be used for children who are older than 3 months of age, and for adults.

Eat as normally as possible

It used to be advised to not eat for a while if you had infectious diarrhoea. However, now it is advised to eat small, light meals if you can. Be guided by your appetite. You may not feel like food and most adults can do without food for a few days. Eat as soon as you are able - but don't stop drinking. If you do feel like eating, avoid fatty, spicy or heavy food at first. Plain foods such as wholemeal bread and rice are good foods to try eating first.


Antidiarrhoeal medicines are not usually necessary for acute diarrhea; however, a 10-14 day supplemental treatment course of dispersible 20 mg zinc tablets shortens diarrhoea duration and improves outcomes.

Woman in bed
For most adults, fluids drunk to keep hydrated should mainly be water.
Photo credit: Unsplash

Summary of key treatment measures

The key measures to remember to treat diarrhoea include:
  • Rehydration drinks: with oral rehydration salts (ORS) solution. ORS is a mixture of clean water, salt and sugar. It costs a few cents per treatment. ORS is absorbed in the small intestine and replaces the water and electrolytes lost in the faeces.
  • Zinc supplements: zinc supplements reduce the duration of a diarrhoea episode by 25% and are associated with a 30% reduction in stool volume.
  • Rehydration: with intravenous fluids in case of severe dehydration or shock, usually in hospital.
  • Nutrient-rich foods: the vicious circle of malnutrition and diarrhoea can be broken by continuing to give nutrient-rich foods – including breast milk – during an episode, and by giving a nutritious diet – including exclusive breastfeeding for the first six months of life – to children when they are well.
  • Consulting a health professional, in particular for management of persistent diarrhoea or when there is blood in stool or if there are signs of dehydration. See 'When should I seek medical advice?' for completeness.

Are there any complications that may occur?

Complications are uncommon in advanced countries. They are more likely in the very young, in pregnant women, or in the elderly. They are also more likely if you have an ongoing (chronic) disease such as diabetes, or if your immune system is not working fully. For example, if you are taking long-term steroid medication or you are having chemotherapy treatment for cancer.

Possible complications include the following:
  • Dehydration (lack of fluid) and electrolyte (salt) imbalance in your body.
  • Reactive complications. Rarely, other parts of the body may react to an infection that occurs in the gut. This can cause symptoms such as joint inflammation (arthritis), skin inflammation and eye inflammation (either conjunctivitis or uveitis). Reactive complications are uncommon if you have a virus causing infectious diarrhoea.
  • Spread of infection to other parts of your body such as your bones, joints, or the meninges that surround your brain and spinal cord. This is rare. If it does occur, it is more likely if diarrhoea is caused by Salmonella spp. infection.
  • Persistent syndromes of diarrhoea may rarely develop.
  • Irritable bowel syndrome is sometimes triggered by a bout of infectious diarrhoea.
  • Lactose intolerance can sometimes occur for a period of time after infectious diarrhoea. This is known as secondary or acquired lactose intolerance. Your gut lining can be damaged by the episode of diarrhoea. This leads to lack of an enzyme called lactase needed to help your body digest a sugar called lactose that is in milk. Lactose intolerance leads to bloating, tummy (abdominal) pain, wind and watery stools after drinking milk. The condition gets better when the infection is over and the gut lining heals. It is more common in children.
  • Haemolytic uraemic syndrome is another potential complication. It is rare and is usually associated with infectious diarrhoea caused by a certain type of Escherichia coli infection. It is a serious condition where there is anaemia, a low platelet count in the blood and kidney failure. It is more common in children. If recognised and treated, most people recover well.
  • Reduced effectiveness of some medicines. During an episode of infectious diarrhoea, certain medicines that you may be taking for other conditions or reasons may not be as effective. This is because the diarrhoea and/or vomiting means that reduced amounts of the medicines are absorbed into your body. Examples of such medicines are medications for epilepsy, diabetes and contraception. Speak to your doctor or nurse if you are unsure of what to do if you are taking other medicines and have acute diarrhoea.

Preventing spread of infection to others

Some infections causing diarrhoea are very easily passed on from person to person. If you have acute diarrhoea, the following are also recommended to prevent the spread of infection to others:
  • Wash your hands thoroughly after going to the toilet. Ideally, use liquid soap in warm running water but any soap is better than none. Dry properly after washing.
  • Don't share towels and flannels.
  • Don't prepare or serve food for others.
  • Regularly clean the toilets that you use. Wipe the flush handle, toilet seat, bathroom taps, surfaces and door handles with hot water and detergent at least once a day. Keep a cloth just for cleaning the toilet (or use a disposable one each time).
  • Stay off work, college, etc, until at least 48 hours after the last episode of diarrhoea or vomiting.
  • Food handlers: if you work with food and develop diarrhoea or vomiting, you must immediately leave the food-handling area. For most, no other measures are needed, other than staying away from work until at least 48 hours after the last episode of diarrhoea or vomiting. Some special situations may arise and sometimes longer time off is needed. Specialist advice may be needed for some uncommon causes of infectious diarrhoea. If in doubt, seek advice from your employer or doctor.
  • If the cause of acute diarrhoea is known to be (or suspected to be) a germ called Cryptosporidium spp., you should not swim in swimming pools for two weeks after the last episode of diarrhoea.

Can infectious diarrhoea be prevented?

Infectious diarrhoea can't always be prevented, but you can reduce your risk greatly with simple hygiene measures. Key measures to prevent diarrhoea include:
  • access to safe drinking-water;
  • use of improved sanitation;
  • hand washing with soap;
  • exclusive breastfeeding for the first six months of life;
  • good personal and food hygiene;
  • health education about how infections spread; and
  • rotavirus vaccination.
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2). MedlinePlus: Diarrhea. Available online:
3). NICE Clinical Guideline (April 2009): Diarrhoea and vomiting in children under 5. Available online:
4). GOV.UK (2005). Preventing person-to-person spread following gastrointestinal infections: guidelines for public health physicians and environmental health officers. Available online:
5). UptoDate. Approach to the adult with acute diarrhea in resource-rich settings. Available online:
6). Ejemot-Nwadiaro RI, Ehiri JE, Arikpo D, et al; Hand washing promotion for preventing diarrhoea. Cochrane Database Syst Rev. 2015 Sep 39:CD004265. doi: 10.1002/14651858.CD004265.pub3.

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