Diarrhea

Food nutrients are absorbed in the small intestine. The remaining waste is pushed into the large intestine (bowel), where water is removed. The resulting feces is stored temporarily in the rectum and then passed out of the body through the anus. Normally, feces are firm, moist, and easy to pass.

Diarrhea is the frequent passing of loose, watery, and unformed feces. Acute diarrhea is the sudden onset of three or more loose stools per day, lasting less than 14 days. The most common cause of acute diarrhea is an infection of the intestines, such as gastroenteritis or food poisoning, and viruses are responsible for most cases.

When the intestinal lining becomes irritated and inflamed, it cannot absorb water from food waste as well as usual, and in severe cases the lining may even leak water. Generally, acute diarrhea resolves on its own after a day or two.

Chronic diarrhea, which lasts four weeks or more, can be caused by a range of conditions that affect the intestines, including inflammatory bowel disease (IBD).

Symptoms#

Symptoms associated with diarrhea can include:

• frequent passing of loose, watery feces
• abdominal cramps or abdominal pain
• an urgent need to go to the toilet

In most cases, acute diarrhea is self-limiting and resolves by itself within a day or two.

When to see a doctor#

Contact your doctor straight away if you have serious symptoms, such as:

• blood in the feces
• pus in the feces
• painful passage of feces
• repeated vomiting
• being unable to increase your fluid intake
• reduced or absent urination
• fever (a temperature greater than 38°C / 100.4°F)

If you have a serious chronic medical condition, such as kidney or heart failure, even one day of diarrhea can be dangerous, so it is safer to see your doctor as soon as possible.

Acute diarrhea can be life threatening to babies and young children, because their smaller bodies are more vulnerable to dehydration. If your baby or young child develops diarrhea, seek medical attention straight away.

Causes of acute diarrhea#

A bout of diarrhea can be caused by a wide range of disorders, infections, and events, including:

• food poisoning
• gastroenteritis
• tropical diseases, such as typhoid and cholera
• anxiety or emotional stress
• overconsumption of alcohol
• some medications, particularly antibiotics

Person-to-person spread, as well as contaminated food and water, are common infectious causes of acute diarrhea. Infectious agents known to cause diarrhea include:

• viruses – such as norovirus, calicivirus, 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 diarrhea#

Chronic diarrhea can have many causes, including:

• medications, including some antibiotics, magnesium-containing antacids, laxatives, and drugs used for conditions such as diabetes, high blood pressure (hypertension), and arthritis, as well as some immunosuppressive drugs
• diverticular disease
• inflammatory bowel disease, including ulcerative colitis and Crohn’s disease
• irritable bowel syndrome, with symptoms such as abdominal pain, bloating, and alternating constipation and diarrhea
• lactose intolerance, the inability to digest the milk sugar lactose
• celiac disease, which reduces the intestine’s ability to absorb food
• chronic constipation
• hormone disorders, such as diabetes or hyperthyroidism (overactive thyroid gland)
• cancer, such as bowel cancer

In one form of chronic diarrhea, the bowel is blocked by hard, impacted feces, but some liquid manages to seep past the blockage. This condition, called “spurious” or “overflow” diarrhea, is more common in older adults.

Diagnosis#

Successful treatment depends on diagnosing the cause. Investigations may include:

• medical history
• physical examination
• blood tests
• laboratory analysis of a stool sample
• colonoscopy – the insertion of a slender instrument through the anus so that the doctor can look at the bowel lining

Always see your doctor if you have serious symptoms, and remember that babies and young children with diarrhea need prompt medical attention.

Treatment#

Treatment for diarrhea depends on the cause, but may include:

• plenty of fluids to prevent dehydration
• oral rehydration drinks to replace lost salts, available from pharmacies; an alternative is one part unsweetened pure fruit juice diluted with four parts water
• intravenous replacement of fluids in severe cases
• anti-diarrheal medications, but only on the advice of your doctor; if your diarrhea is caused by an infection, these drugs may keep the infection inside your body for longer
• treatment for any underlying condition, such as inflammatory bowel disease

Reducing the spread of infection#

Most cases of acute diarrhea are potentially infectious to others. Viruses are easily spread, mainly through direct contact with vomit or feces from an infected person, or through contact with a contaminated object or surface. Occasionally, the virus may be spread by airborne particles generated during vomiting and diarrhea.

To reduce the risk of spreading infection:

• wash your hands carefully after going to the toilet and before handling food
• if you are caring for someone who is unwell, wash your hands thoroughly as well
• stay at home where possible while you have acute diarrhea
• avoid visiting hospitals and nursing homes, and do not swim in public pools

Dietary adjustments#

It may help to make a few short-term dietary adjustments while your bowels recover from acute diarrhea. Be guided by your healthcare professional, but general suggestions include:

• limit fatty, sugary, or spicy foods
• avoid alcohol
• increase your intake of starchy foods such as banana, rice, and bread
• increase your intake of yoghurt containing live cultures

In babies and young children, fruit juice can contribute to diarrhea, so limit these drinks.

Key points#

• The most common cause of acute diarrhea is an intestinal infection, such as gastroenteritis or food poisoning.
• Symptoms include the frequent passing of loose, watery feces, often with abdominal cramps and urgency.
• Contact your doctor immediately if you have serious symptoms, such as a fever over 38°C (100.4°F), blood or pus in the feces, or signs of dehydration.
• Diarrhea can be especially dangerous for babies and young children, because their smaller bodies are more vulnerable to dehydration.
• Person-to-person spread, as well as contaminated food and water, are common infectious causes.

Where to get help and trusted information#

For evidence-based global health guidance, see Source: World Health Organization (WHO).