Globally, an estimated 2 billion cases of diarrheal disease occur each year, and 1.9 million children under the age of 5 years, mostly in developing countries, die from diarrhea.
Diarrhea is characterized by abnormally loose or watery stools.
Some people frequently pass stools, but they are of normal consistency. This is not diarrhea. Similarly, breastfed babies often pass loose, pasty stools. This is normal. It is not diarrhea.
Here are some key points about diarrhea. More detail and supporting information is in the body of this article.
- Most cases of diarrhea are caused by bacteria, viruses, or parasites
- Inflammatory bowel diseases (IBD) including Crohn's disease and ulcerative colitis can cause chronic diarrhea
- Antidiarrheal medications can reduce diarrheal output and zinc supplement is effective in children
- Some nutritional and probiotic interventions may help prevent diarrhea
Correcting dehydration is the priority of diarrhea treatment.
Most cases of diarrhea are caused by an infection in the gastrointestinal tract. The microbes responsible for this infection include:
- parasitic organisms
The most commonly identified causes of acute diarrhea in the United States are the bacteria Salmonella, Campylobacter, Shigella, and Shiga-toxin-producing Escherichia coli.
IBS is a complex of symptoms. There is cramping abdominal pain and altered bowel habits, including diarrhea, constipation, or both.
Inflammatory bowel disease (IBD) is another cause of chronic diarrhea. It is a term used to describe either ulcerative colitis or Crohn's disease. There is often blood in the stool in both conditions.
Other major causes of chronic diarrhea include:
- Microscopic colitis: This is a persistent diarrhea that usually affects older adults, often during the night.
- Malabsorptive and maldigestive diarrhea: The first is caused by impaired nutrient absorption, the second by impaired digestive function. Celiac disease is one example.
- Chronic infections: A history of travel or antibiotic use can be clues to chronic diarrhea. Various bacteria and parasites can be the cause.
- Drug-induced diarrhea: Laxatives and other drugs, including antibiotics, can trigger diarrhea.
- Endocrine causes: Sometimes hormonal factors cause diarrhea, for example, in the case of Addison disease and carcinoid tumors.
- Cancer causes: Neoplastic diarrhea is associated with a number of gut cancers.
Mild cases of acute diarrhea may resolve without treatment. Persistent or chronic diarrhea will be diagnosed and any underlying causes will be treated in addition to the symptoms of diarrhea.
For all cases of diarrhea, rehydration is key:
- Fluids can be replaced by simply drinking more fluids, or they can be received intravenously in severe cases. Children and older people are more vulnerable to dehydration.
- Oral rehydration solution or salts (ORS) refers to water that contains salt and glucose. It is absorbed by the small intestine to replace the water and electrolytes lost in the stool. In developing countries, ORS costs just a few cents. The World Health Organization (WHO) says ORS can safely and effectively treat over 90 percent of non-severe diarrhea cases.
- Oral rehydration products, such as Oralyte and Rehydralyte, are available commercially. Zinc supplementation may reduce the severity and duration of diarrhea in children.
Over-the-counter (OTC) antidiarrheal medicines are also available:
- Loperamide, or Imodium, is an antimotility drug that reduces stool passage.
- Bismuth subsalicylate, for example, Pepto-Bismol, reduces diarrheal stool output in adults and children. It can also be used to prevent traveler's diarrhea.
There is some concern that antidiarrheal medications could prolong bacterial infection by reducing the removal of pathogens through stools.
Antibiotics are only used to treat diarrhea caused by a bacterial infection. If the cause is a certain medication, switching to another drug might be possible.
Nutritionists from Stanford Health Care offer some nutritional tips for diarrhea:
- Sip on clear, still liquids such as fruit juice without added sugar.
- After each loose stool, replace lost fluids with at least one cup of liquid.
- Do most of the drinking between, not during meals.
- Consume high-potassium foods and liquids, such as diluted fruit juices, potatoes without the skin, and bananas.
- Consume high-sodium foods and liquids, such as broths, soups, sports drinks, and salted crackers.
Other advice from the nutritionists is to:
- eat foods high in soluble fiber, such as banana, oatmeal and rice, as these help thicken the stool
- limit foods that may make diarrhea worse, such as creamy, fried, and sugary foods
Foods and drinks that might make the diarrhea worse include:
- sugar-free gum, mints, sweet cherries, and prunes
- caffeinated drinks and medication
- fructose in high amounts, from fruit juices, grapes, honey, dates, nuts, figs, soft drinks, and prunes
- lactose in dairy products
- olestra, or Olean, a fat substitute
There is mixed evidence for the role of probiotics in diarrhea. They may help prevent traveler's diarrhea. In children, there is evidence that they might reduce diarrheal illness by 1 day.
Antibiotic-associated diarrhea might be reduced by the use of probiotics, as may diarrhea related to Clostridium difficile, although the evidence is mixed.
People should ask their doctor for advice, as there are numerous strains. The strain most studied for antibiotic-associated diarrhea are probiotics based on Lactobacillus rhamnosus and Saccharomyces boulardii.
Probiotics to help with Clostridium difficile and antibiotic diarrheas were investigated in a trial published in The Lancet. They found no evidence that a multi-strain preparation of bacteria was effective in preventing these conditions, calling for a better understanding of the development of antibiotic-associated diarrhea.
Probiotics are available in capsules, tablets, powders, and liquids.
Symptoms of diarrhea can include bloating, thirst, and weight loss.
Diarrhea refers to watery stools, but it may be accompanied by other symptoms.
- stomach pain
- abdominal cramps
- weight loss
Diarrhea is a symptom of other conditions, some of which can be serious.
Other possible symptoms are:
- blood or pus in the stools
- persistent vomiting
If these accompany diarrhea, or if the diarrhea is chronic, it may indicate a more serious illness.
Two potentially serious complications of diarrhea are:
- dehydration, with acute or chronic diarrhea
- malabsorption, with chronic diarrhea
Diarrhea can also be a sign of a wide range of underlying chronic conditions. These conditions need to be diagnosed treated to prevent further problems.
Tests and diagnosis
Parasites or their eggs can be seen under a microscope.
The doctor will ask about the symptoms and about any current medications, past medical history, and other medical conditions.
They will also ask:
- when the problem started
- how frequent the stools are
- whether blood is present in the stool
- whether there has been vomiting
- whether the stools are watery, mucus- or pus-filled, and how much stool there is
The doctor will also look for signs of dehydration.
Severe dehydration can be fatal if treatment with rehydration therapy is not given urgently.
Tests for diarrhea
Most cases of diarrhea resolve without treatment, and a doctor will often be able to diagnose the problem without tests.
However, in more severe cases, a stool test may be needed, especially if the patient is very young or old.
Further tests may also be recommended if the patient:
- has signs of fever or dehydration
- has stools with blood or pus
- has severe pain
- has low blood pressure
- has a weakened immune system
- has recently traveled to places outside Western Europe, North America, Australia, and New Zealand
- has recently received antibiotics or been in hospital
- has diarrhea persisting for more than 1 week
If a person has chronic or persistent diarrhea, the doctor will order tests according to the suspected underlying cause.
These may include the following investigations:
- Full blood count: Anemia or a raised platelet count will suggest inflammation.
- Liver function tests: This 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 (ESR) and C-reactive protein (CRP): Raised levels may indicate inflammatory bowel disease (IBD).
- Testing for antibodies: This may detect celiac disease.
When to see a doctor
Diarrhea often resolves without specialist medical treatment, but sometimes it is important to seek a doctor's help.
Infants under 1 year should see a doctor if they have had 6 bouts of diarrhea or 3 bouts of vomiting within 24 hours.
Children over 1 year should see a doctor if they have had 6 episodes or more of diarrhea in 24 hours, or if there is diarrhea and vomiting at the same time.
It is important to seek medical help in the following cases:
- persistent vomiting
- persistent diarrhea
- significant weight loss
- pus in the stool
- blood in the stool, which may turn the stool black
Anyone who experiences diarrhea after surgery, after spending time in hospital, or after using antibiotics, should seek medical assistance.
Adults whose sleep is persistently disturbed by diarrhea may be able to get help to solve this problem.
In developing countries, prevention of diarrhea may be more challenging due to dirty water and poor sanitation.
The following can help prevent diarrhea:
- clean and safe drinking water
- good sanitation systems, for example, waste water and sewage
- good hygiene practices, including handwashing with soap after defecation, after cleaning a child who has defecated, after disposing of a child's stool, before preparing food, and before eating
- breastfeeding for the first 6 months of life
- education on the spread of infection
There is evidence that interventions from public health bodies to promote hand washing can cut diarrhea rates by about one-third.