Diarrhea, also spelled diarrhoea, is the condition of having at least three loose or liquid bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin with loss of the normal stretchiness of the skin and irritable behaviour. This can progress to decreased urination, loss of skin color, a fast heart rate, and a decrease in responsiveness as it becomes more severe. Loose but non-watery stools in babies who are breastfed, however, may be normal.

The most common cause is an infection of the intestines due to either a virus, bacteria, or parasite; a condition known as gastroenteritis. These infections are often acquired from food or water that has been contaminated by stool, or directly from another person who is infected. It may be divided into three types: short duration watery diarrhea, short duration bloody diarrhea, and if it lasts for more than two weeks, persistent diarrhea. The short duration watery diarrhea may be due to an infection by cholera, although this is rare in the developed world. If blood is present it is also known as dysentery. A number of non-infectious causes may also result in diarrhea, including lactose intolerance, irritable bowel syndrome, non-celiac gluten sensitivity, celiac disease, inflammatory bowel disease, hyperthyroidism, and a number of medications. In most cases, stool cultures are not required to confirm the exact cause.

Prevention of infectious diarrhea is by improved sanitation, clean drinking water, and hand washing with soap. Breastfeeding for at least six months is also recommended as is vaccination against rotavirus. Oral rehydration solution (ORS), which is clean water with modest amounts of salts and sugar, is the treatment of choice. Zinc tablets are also recommended. These treatments have been estimated to have saved 50 million children in the past 25 years. When people have diarrhea it is recommended that they continue to eat healthy food and babies continue to be breastfed. If commercial ORS are not available, homemade solutions may be used. In those with severe dehydration, intravenous fluids may be required. Most cases; however, can be managed well with fluids by mouth. Antibiotics, while rarely used, may be recommended in a few cases such as those who have bloody diarrhea and a high fever, those with severe diarrhea following travelling, and those who grow specific bacteria or parasites in their stool. Loperamide may help decrease the number of bowel movements but is not recommended in those with severe disease.

About 1.7 to 5 billion cases of diarrhea occur per year. It is most common in developing countries, where young children get diarrhea on average three times a year. Total deaths from diarrhea are estimated at 1.26 million in 2013 – down from 2.58 million in 1990. In 2012, it was the second most common cause of deaths in children younger than five (0.76 million or 11%). Frequent episodes of diarrhea are also a common cause of malnutrition and the most common cause in those younger than five years of age. Other long term problems that can result include stunted growth and poor intellectual development.


Signs and symptoms associated with diarrhea may include:

  • Loose, watery stools
  • Abdominal cramps
  • Abdominal pain
  • Fever
  • Blood in the stool
  • Bloating
  • Nausea
  • Urgent need to have a bowel movement

When to see a doctor

If you’re an adult, see your doctor if:

  • Your diarrhea persists beyond two days
  • You become dehydrated
  • You have severe abdominal or rectal pain
  • You have bloody or black stools
  • You have a fever above 102 F (39 C)

In children, particularly young children, diarrhea can quickly lead to dehydration. Call your doctor if your child’s diarrhea doesn’t improve within 24 hours or if your baby:

  • Becomes dehydrated
  • Has a fever above 102 F (39 C)
  • Has bloody or black stools


A number of diseases and conditions can cause diarrhea, including

  • Viruses. Viruses that can cause diarrhea include Norwalk virus, cytomegalovirus and viral hepatitis. Rotavirus is a common cause of acute childhood diarrhea.
  • Bacteria and parasites. Contaminated food or water can transmit bacteria and parasites to your body. Parasites such as Giardia lamblia and cryptosporidium can cause diarrhea.
  • Common bacterial causes of diarrhea include campylobacter, salmonella, shigella and Escherichia coli. When traveling in developing countries, diarrhea caused by bacteria and parasites is often called traveler’s diarrhea. Clostridium difficile infection can occur, especially after a course of antibiotics.
  • Medications. Many medications, such as antibiotics, can cause diarrhea. Antibiotics destroy both good and bad bacteria, which can disturb the natural balance of bacteria in your intestines. Other drugs that cause diarrhea are cancer drugs and antacids with magnesium.
  • Lactose intolerance. Lactose is a sugar found in milk and other dairy products. People who have difficulty digesting lactose have diarrhea after eating dairy products.
  • Your body makes an enzyme that helps digest lactose, but for most people, the levels of this enzyme drop off rapidly after childhood. This causes an increased risk of lactose intolerance as you age.
  • Fructose. Fructose, a sugar found naturally in fruits and honey and added as a sweetener to some beverages, can cause diarrhea in people who have trouble digesting it.
  • Artificial sweeteners. Sorbitol and mannitol, artificial sweeteners found in chewing gum and other sugar-free products, can cause diarrhea in some otherwise healthy people.
  • Surgery. Some people have diarrhea after undergoing abdominal surgery or gallbladder removal surgery.
  • Other digestive disorders. Chronic diarrhea has a number of other causes, such as Crohn’s disease, ulcerative colitis, celiac disease, microscopic colitis and irritable bowel syndrome.


Diarrhea can cause dehydration, which can be life-threatening if untreated. Dehydration is particularly dangerous in children, older adults and those with weakened immune systems.

If you have signs of serious dehydration, seek medical help.

Indications of dehydration in adults

These include:

  • Excessive thirst
  • Dry mouth or skin
  • Little or no urination
  • Weakness, dizziness or lightheadedness
  • Fatigue
  • Dark-colored urine

Indications of dehydration in infants and young children

These include:

  • Not having a wet diaper in three or more hours
  • Dry mouth and tongue
  • Fever above 102 F (39 C)
  • Crying without tears
  • Drowsiness, unresponsiveness or irritability
  • Sunken appearance to the abdomen, eyes or cheeks


Treatments for diarrhea

Mild cases of acute diarrhea may resolve without treatment. Persistent or chronic diarrhea will be diagnosed and treated in addition to the symptoms of diarrhea.

For all cases of diarrhea, the first important step in treatment is to rehydrate:

  • 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/salts (ORS) – this is 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 are available commercially – for example Oralyte and Rehydralyte. Zinc supplementation may reduce the severity and duration of diarrhea in children.

OTC antidiarrheal medicines are also available:

  • Loperamide (Imodium, for example) is an antimotility drug that reduces stool passage.
  • Bismuth subsalicylate (for example, Pepto-Bismol) reduces diarrheal stool output in adults and children and may be a safer alternative to loperamide. This drug 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 via 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, replacing lost water after each loose stool with at least one cup of liquid
  • Do most of the drinking between, not during meals
  • Consume high-potassium foods and liquids – examples include diluted fruit juices, potatoes (without the skin), bananas
  • Use high-sodium foods and liquids – broths, soups, sports drinks, salted crackers

Other advice from the nutritionists is to:

  • Eat foods high in soluble fiber to help thicken the stool – bananas, rice, oatmeal, for example
  • Limit certain foods that may make diarrhea worse such as creamy, fried, and sugary foods

Certain food and drink might make the diarrhea worse:

  • Sugar-free gum, mints, sweet cherries, 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
  • Magnesium
  • Olestra (Olean) – a fat substitute


There is mixed evidence for the role of probiotics in diarrhea. In children, there is evidence that they might reduce diarrheal illness by 1 day.

Probiotics may also help prevent traveler’s diarrhea.

Antibiotic-associated diarrhea might be reduced by the use of probiotics, as may diarrhea related to Clostridium difficile, although the evidence is mixed. Advice from the doctor is recommended since there are numerous strains, but the 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.

Tests and diagnosis of diarrhea

The doctor will start by asking questions about the problem, including current medications, past medical history, and other medical conditions.

They will also ask:

  • When the problem started
  • Stool frequency, type (for example, watery, mucus-filled, pussy) and volume
  • Whether blood is present in the stool
  • Whether there has been vomiting

Doctors will also be concerned about whether there is dehydration. Severe dehydration can be fatal if treatment with rehydration therapy is not given urgently.

Tests for diarrhea

Because most cases of diarrhea resolve themselves, and because the diagnosis can be made clinically, tests are not usually required. But in more severe cases, for example, doctors may order further testing.

Acute cases, particularly if the patient is very young or old, may require a stool sample to be tested. Other factors might also need to be investigated; for instance, if the patient:

  • Has signs of fever or dehydration
  • Has stools with blood or pus
  • Has severe pain
  • Has low blood pressure
  • Is immunocompromised
  • 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

Chronic cases of diarrhea will be tested according to the suspected underlying cause, and may include the following investigations:

  • Full blood count – for anemia or a raised platelet count which suggests inflammation
  • Liver function tests, including albumin level
  • Tests for malabsorption – calcium, vitamin B12, folate, iron status (ferritin), thyroid function tests
  • ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein) – with raised levels possibly pointing to inflammatory bowel disease (IBD)
  • Celiac disease testing – for antibodies

Prevention of diarrhea

In developing countries, prevention of diarrhea may be more challenging due to dirty water and poor sanitation. The following practical measures help to prevent the condition:

  • Clean/safe drinking water
  • Good sanitation (toilets and sewerage, for example)
  • 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
  • For mothers with young babies, breastfeeding for the first 6 months of life
  • Good hygiene practices – both personal hygiene and in the kitchen
  • Education on the spread of infection

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



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