Acute Diarrhoea in Adults


Infection of the gut is the common cause. This is called acute infectious diarrhoea. 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. Viruses are easily spread from one person to another by close contact, or when an infected person prepares food for others.

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

What are the symptoms of acute infectious diarrhoea?

The main symptom is diarrhoea, often with vomiting as well. Diarrhoea means loose or watery stools (faeces), usually at least three times in 24 hours. Blood or mucus can appear in the stools with some infections. Crampy pains in your abdomen (tummy) are common. A high temperature (fever), headache and aching limbs sometimes occur.

Symptoms of dehydration

Diarrhea and vomiting may cause dehydration (a lack of fluid in the body). Mild dehydration is common and is usually easily and quickly reversed by drinking lots of fluids. Severe dehydration can be fatal unless quickly treated. This is because the organs of your body need a certain amount of fluid to function.

Dehydration in adults with acute diarrhea is more likely to occur in:

  • Elderly or frail people.
  • Pregnant women.
  • People with severe diarrhea and vomiting. In particular, if you are not able to replace the fluid lost with enough drinks.

Do I need any tests?

Tests are not usually needed. However, if you are particularly unwell, have bloody stools, have recently travelled abroad, are admitted to hospital, or your symptoms are not getting better, then your doctor may ask you to collect a stool sample.

When should I seek medical advice?

  • If you suspect that you are becoming 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 abdominal pain.
  • If you have severe symptoms, or if you feel that your condition is getting worse.
  • If you have a persisting high 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.
  • If you are elderly or have an underlying health problem
  • If you have a weakened immune system.
  • If you are pregnant.

What is the treatment for infectious diarrhoea in adults?

The following are commonly advised until symptoms ease.

Fluids - have lots to drink

As a rough guide, drink at least 200 mls after each bout of diarrhoea (after each watery stool). 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 vomit, 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. It is best not to have drinks that contain a lot of sugar, such as cola, as they can sometimes make diarrhoea worse.

Rehydration drinks 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.

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.


Antidiarrhoeal medicines are not usually necessary. However, you may wish to reduce the number of trips that you need to make to the toilet. You can buy antidiarrhoeal medicines from pharmacies. The safest and most effective is loperamide. The adult dose of this is two capsules at first. This is followed by one capsule after each time you pass some diarrhoea, up to a maximum of eight capsules in 24 hours. It works by slowing down your gut's activity. You should not take loperamide for longer than five days.

Possible complications include the following:

  • Dehydration and salt (electrolyte) imbalance in your body. If dehydration is not treated, kidney failure may also develop. Some people who become severely dehydrated need a drip of fluid directly into a vein. This requires admission to hospital.
  • Reactive complications. Rarely, other parts of the body may react to an infection that occurs in the gut. This can cause symptoms such as arthritis (joint inflammation), 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.
  • 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.
  • 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.

Preventing spread of infection to others

  • Wash your hands thoroughly after going to the toilet.
  • Don't share towels .
  • Don't prepare or serve food for others.
  • Regularly clean the toilets that you use..
  • 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.

Alphabetical Index of Health Topics

If you already know your diagnosis, you may search for the health topic alphabetically here. Hold your cursor over the health topics link in the line below.

Write A Comment


Topic of the Month

Womb Transplant


The new game changer in infertility. Know more about this revolutionary technique.

Continue Reading »

Health Video of the Month

Womb Transplant

Disclaimer: This health video may contain graphic material and viewer discretion is advised.