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Diarrhea in Children

by Deborah M. Consolini, MD

Diarrhea is a very common problem in children. Diarrhea is frequent, loose, or watery bowel movements (BMs) that differ from a child’s normal pattern. Sometimes diarrhea contains blood or mucus. Identifying mild diarrhea may be difficult because in healthy children, the number and consistency of BMs vary with age and diet. For example, breastfed infants who are not yet receiving solid food often have frequent, loose stools that are considered normal. A sudden increase in number and looseness may indicate diarrhea in these infants. However, having watery stools for more than 24 hours is never normal.

Children with diarrhea may lose their appetite, vomit, lose weight, or have a fever. If diarrhea is severe or lasts a long time, dehydration is likely. Infants and young children can become dehydrated more quickly, sometimes in less than 1 day. Severe dehydration can cause seizures, brain damage, and death.

Worldwide, diarrhea causes 2 to 3 million deaths a year mostly in underdeveloped countries. In the United States, diarrhea accounts for about 9% of hospitalizations for children under 5 years old.

Causes

Likely causes of diarrhea depend on whether it lasts less than 2 weeks (acute) or more than 2 weeks (chronic). Most cases of diarrhea are acute.

Common causes

Acute diarrhea is usually caused by

  • Infectious gastroenteritis

  • Food poisoning

  • Use of antibiotics

  • Food allergies

Gastroenteritis is usually caused by a virus, but it can be caused by bacteria or a parasite (see Gastroenteritis in Children).

Food poisoning usually refers to diarrhea, vomiting, or both caused by eating food contaminated by toxins produced by certain bacteria, such as staphylococci (see Staphylococcal Food Poisoning) or clostridia (see Clostridium perfringens Food Poisoning).

Certain antibiotics can alter the types and number of bacteria in the intestine. As a result, diarrhea can occur. Sometimes using antibiotics enables a particularly dangerous bacteria, Clostridium difficile, to multiply. Clostridium difficile releases toxins that can cause inflammation of the lining of the large intestine (colitis—see Clostridium difficile -Induced Colitis).

Chronic diarrhea is usually caused by

  • Dietary factors, such as lactose intolerance or overconsumption of certain foods

  • Infections (particularly those caused by parasites)

  • Celiac disease

  • Inflammatory bowel disease


Less common causes

Acute diarrhea can also result from more serious disorders such as appendicitis, intussusception, and hemolytic-uremic syndrome (a complication of certain types of bacterial infection—see Thrombotic thrombocytopenic purpura (TTP) and hemolytic-uremic syndrome (HUS)). These serious disorders are usually associated with other worrisome symptoms besides diarrhea, such as severe abdominal pain or swelling, bloody stools, fever, and ill appearance.

Chronic diarrhea can also result from disorders that interfere with the absorption of food (malabsorption disorders—see Overview of Malabsorption), such as cystic fibrosis, and a weakened immune system (due to a disorder such as AIDS or use of certain drugs).

Diarrhea sometimes results from constipation. When hardened stool accumulates in the rectum, soft stool may leak around it and into the child's underwear.


Evaluation

Warning signs

Certain symptoms are cause for concern. They include

  • Signs of dehydration, such as decreased urination, lethargy or listlessness, crying without tears, extreme thirst, and a dry mouth

  • Ill appearance

  • Blood in stool

  • Pain in the abdomen and, when touched, extreme tenderness

  • Bleeding in the skin (seen as tiny reddish purple dots [petechiae] or splotches [purpura])


When to see a doctor

Children with any warning signs should be evaluated by a doctor right away, as should those who have had more than 3 or 4 episodes of diarrhea and are not drinking or are drinking very little.

If children have no warning signs and are drinking and urinating normally, the doctor should be called if diarrhea lasts 2 days or more or if there are more than 6 to 8 episodes of diarrhea a day. If diarrhea is mild, a doctor’s visit is unnecessary. Children with diarrhea for 14 days or more should be seen by a doctor.


What the doctor does

Doctors first ask questions about symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause and the tests that may need to be done (see Some Causes of Diarrhea).

Doctors ask what the BMs look like, how frequent they are, how long they last, and whether the child has other symptoms, such as fever, vomiting, or abdominal pain.

Doctors also ask about potential causes, such as diet, use of antibiotics, consumption of possibly contaminated food, recent contact with animals, and recent travel.

A physical examination is done, looking for symptoms of dehydration and disorders that can cause diarrhea. The abdomen is checked for swelling and tenderness. Doctors also evaluate growth.

Some Causes and Features of Diarrhea

Cause

Common Features*

Tests

Acute (lasting less than 2 weeks)

Antibiotic use

Recent use of antibiotics

Often no other symptoms

A doctor’s examination

Sometimes tests for Clostridium difficile toxin in stool

Gastroenteritis due to viruses, bacteria, or parasites

Often with vomiting

Dehydration common especially among infants and young children

Sometimes fever and abdominal pain

Rarely blood in stool

Sometimes recent contact with infected people (such as those at a day care center, at a camp, or on a cruise), with animals at a petting zoo (where Escherichia [E.] coli may be acquired), or with reptiles (which may be infected with Salmonella bacteria) or recent consumption of undercooked, contaminated food or contaminated water

A doctor’s examination

Sometimes examination and testing of stool

Food allergy

Hives, swelling of the lips, and difficulty breathing within minutes to several hours after eating

Sometimes vomiting

Often an already identified food allergy

A doctor’s examination

Hemolytic-uremic syndrome

Abdominal pain, vomiting, and usually bloody diarrhea for a few days, followed by development of pale skin and decreased urination

Sometimes bleeding in the skin (seen as tiny reddish purple dots or splotches)

Blood tests

Examination and testing of stool

Chronic (lasting 2 weeks or more)

Allergy to cow's milk protein

Vomiting

Poor feeding

Weight loss, poor growth, or both

Blood in stools

Stool tests

Symptoms that lessen when the formula is changed

Possibly endoscopy, colonoscopy, or both

Excessive consumption of fruit juices (especially apple, pear, and prune)

Drinking more than 4–8 ounces of fruit juice a day

Often no other symptoms except diarrhea

A doctor’s examination

Resolution of diarrhea after decreasing consumption of fruit juices

Inflammatory bowel disease such as

  • Crohn disease

  • Ulcerative colitis

Blood in stool, crampy abdominal pain, weight loss, loss of appetite, and poor growth

Sometimes arthritis, rashes, sores in the mouth, and tears in the rectum

Colonoscopy

Sometimes CT or x-rays after barium is inserted in the rectum (barium enema)

Lactose intolerance (inability to digest lactose, the sugar in milk and dairy products )

Abdominal bloating, passing of gas (flatulence), and explosive diarrhea

Diarrhea after consumption of milk and dairy products

A doctor’s examination

Sometimes a breath test to detect hydrogen (indicates undigested carbohydrates)

Examination and analysis of stool to check for unabsorbed carbohydrates

Malabsorption disorders such as

  • Celiac disease

  • Cystic fibrosis

  • Acrodermatitis enteropathica

Light-colored, soft, bulky, and unusually foul-smelling stool that may appear oily

Abdominal bloating and flatulence

Poor weight gain

With cystic fibrosis, frequent respiratory infections

With acrodermatitis enteropathica, rash and cracks in the corners of the mouth

Examination and testing of stool

If celiac disease is suspected, blood tests to measure antibodies against gluten (a protein in wheat) and biopsy of the small intestine

If cystic fibrosis is suspected, a sweat test and possibly genetic testing

If acrodermatitis enteropathica is suspected, a blood test for zinc deficiency

A weakened immune system due to

  • HIV infection or an immunodeficiency disorder

  • Use of drugs that suppress the immune system

Frequent infections

Weight loss or poor weight gain

Sometimes an already identified HIV infection

Blood tests for HIV

A complete blood cell count and other blood tests to evaluate the immune system

*Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present.

Infections by bacteria, parasites, or viruses can also cause chronic diarrhea.

CT = computed tomography; HIV = human immunodeficiency virus.


Testing

If diarrhea lasts less than 2 weeks, the cause is probably gastroenteritis due to a virus, and testing is usually unnecessary. However, if doctors suspect another cause, tests are done to check for it.

Tests are also done when children have warning signs. If they have signs of dehydration, blood tests are done to measure levels of electrolytes (calcium and other minerals necessary to maintain the fluid balance in the body). If other warning signs are present, tests may include a complete blood cell count, urine tests, examination and analysis of stool, abdominal x-rays, or a combination.


Treatment

Specific causes are treated. For example, if children have celiac disease, gluten is removed from their diet. Antibiotics that cause diarrhea are stopped if a doctor recommends it. Gastroenteritis due to a virus usually disappears without treatment.

Drugs to stop diarrhea, such as loperamide, are not recommended for infants and young children.

Dehydration

Because the main concern in children is dehydration, treatment focuses on giving fluids and electrolytes (see see Dehydration in Children). Most children with diarrhea are successfully treated with fluids given by mouth (orally). Fluids are given by vein (intravenously) only if children are not drinking or are severely dehydrated. Oral rehydration solutions that contain the right balance of carbohydrates and sodium are used. In the United States, these solutions are widely available without a prescription from pharmacies and most supermarkets. Sports drinks, sodas, juices, and similar drinks have too little sodium and too much carbohydrate and should not be used.

If children are also vomiting, small, frequent amounts of fluid are given at first. Typically, 1 teaspoon (5 milliliters) is given every 5 minutes. If children keep this amount down, the amount is gradually increased. With patience and encouragement, most children can take enough fluid by mouth to avoid the need for intravenous fluid. However, children with severe dehydration may need intravenous fluids.


Diet

As soon as children have received sufficient fluids and are not vomiting, they should be given an age-appropriate diet. Infants may resume breast milk or formula.

In children with chronic diarrhea, the treatment depends on the cause, but providing and maintaining adequate nutrition and monitoring for possible vitamin or mineral deficiencies is most important.


Key Points

  • Diarrhea is common among children.

  • Gastroenteritis, usually due to a virus, is the most common cause.

  • Children should be evaluated by a doctor if they have any warning sign (such as signs of dehydration, severe abdominal pain, fever, or blood or pus in stool).

  • Testing is rarely necessary when diarrhea lasts less than 2 weeks.

  • Dehydration is likely if diarrhea is severe or lasts a long time.

  • Giving fluids by mouth effectively treats dehydration in most children.

  • Drugs to stop diarrhea, such as loperamide, are not recommended for infants and young children.

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