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Diarrhea can range from a mild, temporary condition to a potentially life threatening one. Viruses, bacteria, and parasites are the most common causes of diarrhea.

Globally, an estimated 2 billion cases of diarrheal disease occur each year. Also, around 1.9 million children under the age of 5 years — mostly in developing countries — die from diarrhea every year. This makes it the second leading cause of death in this age group.

Diarrhea is characterized by abnormally loose or watery stools. Most cases of diarrhea are due to bacteria, viruses, or parasites. Digestive system disorders can also cause chronic diarrhea.

If a person frequently passes stools but they are of a normal consistency, this is not diarrhea. Similarly, breastfed babies often pass loose, sticky stools. This is normal.

This article looks at the causes and treatments of diarrhea. It also looks at symptoms, diagnosis, prevention, and when to see a doctor.

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Many cases of diarrhea are due to an infection in the gastrointestinal tract. The microbes responsible for this infection include:

  • bacteria
  • viruses
  • parasitic organisms

The most commonly identified causes of acute diarrhea in the United States are the bacteria Salmonella, Campylobacter, Shigella, and Escherichia coli.

Some cases of chronic diarrhea are called “functional” because although all the digestive organs appear normal, they are not functioning as they ideally should. In the developed world, irritable bowel syndrome (IBS) is the most common cause of functional diarrhea.

IBS causes many symptoms, including cramping, abdominal pain, and altered bowel habits, which can include diarrhea, constipation, or both.

Inflammatory bowel disease (IBD) is another cause of chronic diarrhea. IBD describes either ulcerative colitis or Crohn’s disease. Both conditions can also cause blood in the stool.

Some other major causes of chronic diarrhea include:

  • Microscopic colitis: This is a persistent type of diarrhea that usually affects older adults. It develops due to inflammation and occurs often during the night.
  • Malabsorptive and maldigestive diarrhea: The first is due to impaired nutrient absorption, and the second is due to impaired digestive function. Celiac disease is one example.
  • Chronic infections: A history of travel or antibiotic use can be clues in chronic diarrhea. Various bacteria and parasites can also be the cause.
  • Drug-induced diarrhea: Laxatives and other drugs, including antibiotics, can trigger diarrhea.
  • Endocrine-related causes: Sometimes, hormonal factors cause diarrhea. This is the case in Addison’s disease and carcinoid tumors.
  • Cancer-related causes: Neoplastic diarrhea is associated with a number of gut cancers.

Mild cases of acute diarrhea may resolve without treatment.

For persistent or chronic diarrhea, a doctor will treat any underlying causes in addition to the symptoms of diarrhea.

The sections below will discuss some possible treatment options in more detail.


Children and older people are particularly vulnerable to dehydration. For all cases of diarrhea, rehydration is vital.

People can replace fluids by simply drinking more of them. In severe cases, however, a person may need intravenous fluids.

Oral rehydration solution or salts (ORS) refers to water that contains salt and glucose. The small intestine absorbs the solution to replace the water and electrolytes lost in the stool. In developing countries, ORS costs just a few cents.

The World Health Organization (WHO) say that ORS can safely and effectively treat over 90% of nonsevere diarrhea cases.

Zinc supplementation may also reduce the severity and duration of diarrhea in children. Various products are available to purchase online.

Antidiarrheal medication

Over-the-counter antidiarrheal medications are also available. These include loperamide (Imodium) and bismuth subsalicylate (Pepto-Bismol).

Imodium is an antimotility drug that reduces stool passage. It is available to purchase over the counter or online.

Pepto-Bismol reduces diarrheal stool output in adults and children. It can also prevent traveler’s diarrhea. People can buy this product online or over the counter.

There is some concern that antidiarrheal medications could prolong bacterial infection by reducing the removal of pathogens through stools.


Antibiotics can only treat diarrhea due to bacterial infections. If the cause is a certain medication, switching to another drug might help.

Always talk to a doctor before switching medications.


The following diet tips may help with diarrhea:

  • sipping on clear liquids, such as electrolyte drinks, water, or fruit juice without added sugar
  • after each loose stool, replacing lost fluids with at least 1 cup of liquid
  • doing most of the drinking between, not during, meals
  • consuming high potassium foods and liquids, such as diluted fruit juices, potatoes without the skin, and bananas
  • consuming high sodium foods and liquids, such as broths, soups, sports drinks, and salted crackers
  • eating foods high in soluble fiber, such as banana, oatmeal, and rice, as these help thicken the stool
  • limiting foods that may make diarrhea worse, such as creamy, fried, high dairy, and sugary foods

Foods and beverages that might make diarrhea worse include:

  • sugar-free gum, mints, sweet cherries, and prunes
  • caffeinated drinks and medications
  • fructose in high amounts, from fruit juices, grapes, honey, dates, nuts, figs, soft drinks, and prunes
  • lactose in dairy products
  • magnesium
  • olestra (Olean), which is a fat substitute
  • anything that contains artificial sweeteners

Learn more about foods to eat with diarrhea here.


There is mixed evidence for the role of probiotics in diarrhea. They may help prevent traveler’s diarrhea, and in children, there is evidence to suggest that they might reduce diarrheal illness by 1 day.

People should ask their doctor for advice, as there are numerous strains. Researchers have most studied probiotics based on Lactobacillus rhamnosus and Saccharomyces boulardii for antibiotic-associated diarrhea.

Research in The Lancet found no evidence to suggest that a multistrain preparation of bacteria was effective in preventing Clostridium difficile or antibiotic-related diarrhea. They call for a better understanding of the development of antibiotic-associated diarrhea.

Probiotics come in capsules, tablets, powders, and liquids, and they are available online.

Diarrhea refers to watery stools, but it may be accompanied by other symptoms. These include:

  • stomach pain
  • abdominal cramps
  • bloating
  • weight loss
  • fever
  • body aches
  • chills

Diarrhea is also a symptom of other conditions, some of which can be serious. Other possible symptoms are:

  • blood or pus in the stool
  • persistent vomiting
  • dehydration

If any of these accompany diarrhea, or if the diarrhea is chronic, it may indicate a more serious illness.

Two potentially serious complications of diarrhea are dehydration (in cases of severe and frequent diarrhea) and malabsorption (in cases of chronic diarrhea).

Diarrhea can also indicate a wide range of underlying chronic conditions. Diagnosis and treatment can help prevent further problems.

When diagnosing the cause of diarrhea, a doctor will ask about the person’s symptoms and:

  • any current medications they take
  • their past medical history
  • their family history
  • their travel history
  • any other medical conditions they have

They will also ask:

  • when the diarrhea started
  • how frequent the stools are
  • if blood is present in the stool
  • if the person has been vomiting
  • whether the stools are watery or contain mucus or pus
  • how much stool there is

They will also look for signs of dehydration. Severe dehydration can be fatal if the person does not receive rehydration therapy immediately.

Tests for diarrhea

Most cases of diarrhea resolve without treatment, and a doctor will often be able to diagnose the problem without the use of tests.

However, in more severe cases, a stool test may be necessary — especially if the symptoms persist for longer than a week.

The doctor may also recommend further tests if the person has:

  • signs of fever or dehydration
  • stools with blood or pus
  • severe pain
  • low blood pressure
  • a weakened immune system
  • recently traveled
  • recently received antibiotics or been in the hospital
  • diarrhea persisting for longer than 1 week

If a person has chronic or persistent diarrhea, the doctor will order tests according to the suspected cause.

These may include:

  • A full blood count: Anemia may suggest malnutrition, bleeding ulcerations, or IBD.
  • Liver function tests: These will include testing albumin levels.
  • Tests for malabsorption: These will check the absorption of calcium, vitamin B-12, and folate. They will also assess iron status and thyroid function.
  • Erythrocyte sedimentation rate and C-reactive protein: Raised levels may indicate IBD.
  • Tests for antibodies: These may detect celiac disease.
  • Stool tests: Doctors can identify parasites, bacteria, and a few viruses in stool cultures. Stool tests can also reveal microscopic blood, white blood cells, and other clues for diagnosis.

Diarrhea often resolves without medical treatment, but it is important to seek medical help when there is:

  • persistent vomiting
  • persistent diarrhea
  • dehydration
  • significant weight loss
  • pus in the stool
  • blood in the stool, which may turn the stool black if it is coming from higher up in the gastrointestinal tract

Anyone who experiences diarrhea after surgery, after spending time in the hospital, or after using antibiotics should seek medical attention.

Adults who lose sleep due to diarrhea should also seek medical care as soon as possible, as this is usually a sign of more serious causes.

Children should see a doctor as soon as possible if they have had more than five bouts of diarrhea or vomited more than twice within 24 hours.

The following can help prevent diarrhea:

  • drinking clean and safe water only
  • having good sanitation systems, such as wastewater and sewage
  • having good hygiene practices, such as regularly washing the hands with soap, especially before preparing food and eating and after using the bathroom
  • educating oneself on the spread of infection

There is evidence to suggest that interventions from public health bodies to promote hand-washing can reduce diarrhea rates by about one-third.

In developing countries, however, the prevention of diarrhea may be more challenging due to dirty water and poor sanitation.

Diarrhea is a common problem with many potential causes.

In most cases, a range of home remedies and medical treatments can help. However, a person should see their doctor if they are concerned about diarrhea or other symptoms.