Diarrhea

What is diarrhea?

Diarrhea is an increase in the frequency of bowel movements or a decrease in the form of stool (greater looseness of stool). Although changes in frequency of bowel movements and looseness of stools can vary independently of each other, changes often occur in both.

Diarrhea needs to be distinguished from four other conditions. Although these conditions may accompany diarrhea, they often have different causes and different treatments than diarrhea. These other conditions are:

1.     incontinence of stool, which is the inability to control (delay) bowel movements until an appropriate time, for example, until one can get to the toilet

2.     rectal urgency, which is a sudden urge to have a bowel movement that is so strong that if a toilet is not immediately available there will be incontinence

3.     incomplete evacuation, which is a sensation that another bowel movement is necessary soon after a bowel movement, yet there is difficulty passing further stool the second time

4.     bowel movements immediately after eating a meal

How is diarrhea defined?

Diarrhea can be defined in absolute or relative terms based on either the frequency of bowel movements or the consistency (looseness) of stools.

Frequency of bowel movements. Absolute diarrhea is having more bowel movements than normal. Thus, since among healthy individuals the maximum number of daily bowel movements is approximately three, diarrhea can be defined as any number of stools greater than three. Relative diarrhea is having more bowel movements than usual. Thus, if an individual who usually has one bowel movement each day begins to have two bowel movements each day, then diarrhea is present-even though there are not more than three bowel movements a day, that is, there is not absolute diarrhea.

Consistency of stools. Absolute diarrhea is more difficult to define on the basis of the consistency of stool because the consistency of stool can vary considerably in healthy individuals depending on their diets. Thus, individuals who eat large amounts of vegetables will have looser stools than individuals who eat few vegetables. Stools that are liquid or watery are always abnormal and considered diarrheal. Relative diarrhea is easier to define based on the consistency of stool. Thus, an individual who develops looser stools than usual has diarrhea--even though the stools may be within the range of normal with respect to consistency

Why does diarrhea develop?

With diarrhea, stools usually are looser whether or not the frequency of bowel movements is increased. This looseness of stool--which can vary all the way from slightly soft to watery--is caused by increased water in the stool. During normal digestion, food is kept liquid by the secretion of large amounts of water by the stomach, upper small intestine, pancreas, and gallbladder. Food that is not digested reaches the lower small intestine and colon in liquid form. The lower small intestine and particularly the colon absorb the water, turning the undigested food into a more-or-less solid stool with form. Increased amounts of water in stool can occur if the stomach and/or small intestine secretes too much fluid, the distal small intestine and colon do not absorb enough water, or the undigested, liquid food passes too quickly through the small intestine and colon for enough water to be removed. Of course, more than one of these abnormal processes may occur at the same time.

For example, some viruses, bacteria and parasites cause increased secretion of fluid, either by invading and inflaming the lining of the small intestine (inflammation stimulates the lining to secrete fluid) or by producing toxins (chemicals) that also stimulate the lining to secrete fluid but without causing inflammation. Inflammation of the small intestine and/or colon from bacteria or from ileitis/colitis can increase the rapidity with which food passes through the intestines, reducing the time that is available for absorbing water. Conditions of the colon such as collagenous colitis can block the ability of the colon to absorb water.

Diarrhea generally is divided into two types, acute and chronic.

• Acute diarrhea lasts from a few days up to a week.
• Chronic diarrhea can be defined in several ways but almost always lasts more than three weeks.

It is important to distinguish between acute and chronic diarrhea because they usually have different causes, require different diagnostic tests, and require different treatment

What are common causes of acute diarrhea?

The most common cause of acute diarrhea is infection--viral, bacterial, and parasitic. Bacteria also can cause acute food poisoning. A third important cause of acute diarrhea is starting a new medication.

Viral gastroenteritis

Viral gastroenteritis (viral infection of the stomach and the small intestine) is the most common cause of acute diarrhea worldwide. Symptoms of viral gastroenteritis (nausea, vomiting, abdominal cramps, and diarrhea) typically last only 48-72 hrs. Unlike bacterial enterocolitis (bacterial infection of the small intestine and colon), patients with viral gastroenteritis usually do not have blood or pus in their stools and have little if any fever.

Viral gastroenteritis can occur in a sporadic form (in a single individual) or in an epidemic form (among groups of individuals). Sporadic diarrhea probably is caused by several different viruses and is believed to be spread by person-to-person contact. The most common cause of epidemic diarrhea (for example, on cruise ships) is infection with a family of viruses known as caliciviruses of which the genus norovirus is the most common (for example, "Norwalk agent"). The caliciviruses are transmitted by food that is contaminated by sick food-handlers or by person-to-person contact.

Food poisoning

Food poisoning is a brief illness that is caused by toxins produced by bacteria. The toxins cause abdominal pain (cramps) and vomiting and also cause the small intestine to secrete large amounts of water that leads to diarrhea. The symptoms of food poisoning usually last less than 24 hours. With some bacteria, the toxins are produced in the food before it is eaten, while with other bacteria, the toxins are produced in the intestine after the food is eaten.

Symptoms usually appear within several hours when food poisoning is caused by toxins that are formed in the food before it is eaten. It takes longer for symptoms to develop when the toxins are formed in the intestine (because it takes time for the bacteria to produce the toxins). Therefore, in the latter case, symptoms usually appear after 7-15 hours.

Staphylococcus aureus is an example of a bacterium that produces toxins in food before it is eaten. Typically, food contaminated with Staphylococcus (such as salad, meat or sandwiches with mayonnaise) is left un-refrigerated at room temperature overnight. The Staphylococcal bacteria multiply in the food and produce toxins. Clostridium perfringens is an example of a bacterium that multiplies in food (usually canned food), and produces toxins in the small intestine after the contaminated food is eaten.

Traveler's diarrhea

There are many strains of E. coli bacteria. Most of the E. coli bacteria are normal inhabitants of the small intestine and colon and are non-pathogenic, meaning they do not cause disease in the intestines. Nevertheless, these non-pathogenic E. coli can cause diseases if they spread outside of the intestines, for example, into the urinary tract (where they cause bladder or kidney infections) or into the blood stream (sepsis).

Certain strains of E. coli, however, are pathogenic (meaning they can cause disease in the small intestine and colon). These pathogenic strains of E. coli cause diarrhea either by producing toxins (called enterotoxigenic E. coli or ETEC) or by invading and inflaming the lining of the small intestine and the colon and causing enterocolitis (called enteropathogenic E. coli or EPEC). Traveler's diarrhea usually is caused by an ETEC strain of E. coli that produces a diarrhea-inducing toxin.

Tourists visiting foreign countries with warm climates and poor sanitation (Mexico, parts of Africa, etc.) can acquire ETEC by eating contaminated foods such as fruits, vegetables, seafood, raw meat, water, and ice cubes. Toxins produced by ETEC cause the sudden onset of diarrhea, abdominal cramps, nausea, and sometimes vomiting. These symptoms usually occur 3-7 days after arrival in the foreign country and generally subside within 3 days. Occasionally, other bacteria or parasites can cause diarrhea in travelers (for example, Shigella, Giardia, Campylobacter). Diarrhea caused by these other organisms usually lasts longer than 3 days.

Bacterial enterocolitis

Disease-causing bacteria usually invade the small intestines and colon and cause enterocolitis (inflammation of the small intestine and colon). Bacterial enterocolitis is characterized by signs of inflammation (blood or pus in the stool, fever) and abdominal pain and diarrhea. Campylobacter jejuni is the most common bacterium that causes acute enterocolitis in the U.S. Other bacteria that cause enterocolitis include Shigella, Salmonella, and EPEC. These bacteria usually are acquired by drinking contaminated water or eating contaminated foods such as vegetables, poultry, and dairy products.

Enterocolitis caused by the bacterium Clostridium difficile is unusual because it often is caused by antibiotic treatment. Clostridium difficile is also the most common nosocomial infection (infection acquired while in the hospital) to cause diarrhea. Unfortunately, infection also is increasing among individuals who have neither taken antibiotics or been in the hospital.

E. coli O157:H7 is a strain of E. coli that produces a toxin that causes hemorrhagic enterocolitis (enterocolitis with bleeding). There was a famous outbreak of hemorrhagic enterocolitis in the U.S. traced to contaminated ground beef in hamburgers (hence it is also called hamburger colitis). Approximately 5% of patients infected with E. coli O157:H7, particularly children, can develop hemolytic uremic syndrome (HUS), a syndrome that can lead to kidney failure . Some evidence suggests that prolonged use of anti-diarrhea agents or use of antibiotics may increase the chance of developing HUS.

Parasites

Parasitic infections are not common causes of diarrhea in the U. S. Infection with Giardia lamblia occurs among individuals who hike in the mountains or travel abroad and is transmitted by contaminated drinking water. Infection with Giardia usually is not associated with inflammation; there is no blood or pus in the stool and little fever. Infection with amoeba (amoebic dysentery) usually occurs during travel abroad to undeveloped countries and is associated with signs of inflammation--blood or pus in the stool and fever.

Cryptosporidium is a diarrhea-producing parasite that is spread by contaminated water because it can survive chlorination. Cyclospora is a diarrhea-producing parasite that has been associated with contaminated raspberries from Guatemala.

Drugs

Drug-induced diarrhea is very common because many drugs cause diarrhea. The clue to drug-induced diarrhea is that the diarrhea begins soon after treatment with the drug is begun. The medications that most frequently cause diarrhea are antacids and nutritional supplements that contain magnesium. Other classes of medication that cause diarrhea include:

• nonsteroidal anti-inflammatory drugs (NSAIDs),
• chemotherapy medications,
• antibiotics,
• medications to control irregular heartbeats (antiarrhythmics), and
• medications for high blood pressure.

A few examples of specific medications that commonly cause diarrhea are:

• misoprostol (Cytotec),
• quinidine (Quinaglute, Quinidex),
• olsalazine (Dipentum),
• colchicine (Colchicine),
• metoclopramide (Reglan), and
• cisapride (Propulsid, Motilium).

What are common causes of chronic diarrhea?

Irritable bowel syndrome. The irritable bowel syndrome (IBS) is a functional cause of diarrhea or constipation. Inflammation does not typically exist in the affected bowel. (Nevertheless, recent information suggests that there MAY be a component of inflammation in IBS.) It may be caused by several different underlying problems, but it is believed that the most common cause is rapid passage of the intestinal contents through the colon.
Infectious diseases. There are a few infectious diseases that can cause chronic diarrhea, for example, Giardia lamblia . Patients with AIDS often have chronic infections of their intestines that cause diarrhea.
Bacterial overgrowth of the small intestine. Because of small intestinal problems, normal colonic bacteria may spread from the colon and into the small intestine. When they do, they are in a position to digest food that the small intestine has not had time to digest and absorb. The mechanism that leads to the development of diarrhea in bacterial overgrowth is not known.
Post-infectious. Following acute viral, bacterial or parasitic infections, some individuals develop chronic diarrhea. The cause of this type of diarrhea is not clear, but some of the individuals have bacterial overgrowth of the small intestine. This condition also is referred to as post-infectious IBS.
Inflammatory bowel disease (IBD). Crohn's disease and ulcerative colitis, diseases causing inflammation of the small intestine and/or colon, commonly cause chronic diarrhea.
Colon cancer. Colon cancer can cause either diarrhea or constipation. If the cancer blocks the passage of stool, it usually causes constipation. Sometimes, however, there is secretion of water behind the blockage, and liquid stool from behind the blockage leaks around the cancer and results in diarrhea. Cancer, particularly in the distal part of the colon, can lead to thin stools. Cancer in the rectum can lead to a sense of incomplete evacuation.
Severe constipation. By blocking the colon, hardened stool can lead to the same problems as colon cancer, as discussed previously.
Carbohydrate (sugar) malabsorption. Carbohydrate or sugar malabsorption is an inability to digest and absorb sugars. The most well-recognized malabsorption of sugar occurs with lactase deficiency (also known as lactose or milk intolerance) in which milk products containing the milk sugar, lactose, lead to diarrhea. The lactose is not broken up in the intestine because of the absence of an intestinal enzyme, lactase, that normally breaks up lactose. Without being broken up, lactose cannot be absorbed into the body. The undigested lactose reaches the colon and pulls water (by osmosis) into the colon. This leads to diarrhea. Although lactose is the most common form of sugar malabsorption, other sugars in the diet also may cause diarrhea, including fructose and sorbitol.
Fat malabsorption. Malabsorption of fat is the inability to digest or absorb fat. Fat malabsorption may occur because of reduced pancreatic secretions that are necessary for normal digestion of fat (for example, due to pancreatitis or pancreatic cancer) or by diseases of the lining of the small intestine that prevent the absorption of digested fat (for example, celiac disease). Undigested fat enters the last part of the small intestine and colon where bacteria turn it into substances (chemicals) that cause water to be secreted by the small intestine and colon. Passage through the small intestine and colon also may be more rapid when there is malabsorption of fat.
Endocrine diseases. Several endocrine diseases (imbalances of hormones) may cause diarrhea, for example, an over-active thyroid gland (hyperthyroidism) and an under-active pituitary or adrenal gland (Addison's disease).
Laxative abuse. The abuse of laxatives by individuals who want attention or to lose weight is an occasional cause of chronic diarrhea.

What are the complications of diarrhea?

Dehydration occurs when there is excessive loss of fluids and minerals (electrolytes) from the body due to diarrhea, with or without vomiting.

• Dehydration is common among adult patients with acute diarrhea who have large amounts of stool, particularly when the intake of fluids is limited by lethargy or is associated with nausea and vomiting.
• It also is common in infants and young children who develop viral gastroenteritis or bacterial infection.
• Patients with mild dehydration may experience only thirst and dry mouth.
• Moderate to severe dehydration may cause orthostatic hypotension with syncope (fainting upon standing due to a reduced volume of blood, which causes a drop in blood pressure upon standing), a diminished urine output, severe weakness, shock, kidney failure, confusion, acidosis (too much acid in the blood), and coma.

Electrolytes (minerals) also are lost with water when diarrhea is prolonged or severe, and mineral or electrolyte deficiencies may occur. The most common deficiencies occur with sodium and potassium. Abnormalities of chloride and bicarbonate also may develop.

Finally, there may be irritation of the anus due to the frequent passage of watery stool containing irritating substances.

When should the doctor be called for diarrhea?

Most episodes of diarrhea are mild and of short duration and do not need to be brought to the attention of a doctor. The doctor should be consulted when there is:

• High fever (temperature greater than 101 F)

• Moderate or severe abdominal pain or tenderness

• Bloody diarrhea that suggests severe intestinal inflammation

• Diarrhea in persons with serious underlying illness for whom dehydration may have more serious consequences, for example, persons with diabetes, heart disease, and AIDS

• Severe diarrhea that shows no improvement after 48 hours.

• Moderate or severe dehydration

• Prolonged vomiting that prevents intake of fluids orally

• Acute diarrhea in pregnant women because of concern for the health of the fetus

• Diarrhea that occurs during or immediately after completing a course of antibiotics because the diarrhea may represent antibiotic-associated infection with C. difficile that requires treatment

• Diarrhea after returning from developing countries or from camping in the mountains because there may be infection with Giardia (for which there is treatment)

• Diarrhea that develops in patients with chronic intestinal diseases such as colitis, or Crohn's disease because the diarrhea may represent worsening of the underlying disease or a complication of the disease, both requiring treatment

• Acute diarrhea in an infant or young child in order to ensure the appropriate use of oral liquids (type, amount, and rate), to prevent or treat dehydration, and to prevent complications of inappropriate use of liquids such as seizures and abnormal blood electrolytes

• Chronic diarrhea

What tests are useful in the evaluation of diarrhea?

Acute diarrhea. Acute diarrhea usually requires few tests.

• Measurement of blood pressure in the upright and supine (lying) positions can demonstrate orthostatic hypotension and confirm the presence of dehydration. If moderate or severe dehydration or electrolyte deficiencies are likely, blood electrolytes can be measured.
• Examination of a small amount of stool under the microscope may reveal white blood cells indicating that intestinal inflammation is present and prompting further testing, particularly bacterial cultures of stool and examination of stool for parasites.
• If antibiotics have been taken within the previous two weeks, stool should be tested for the toxin of C. difficile.
• Testing stool or blood for viruses is performed only rarely, since there is no specific treatment for the viruses that cause gastroenteritis.
• If there has been recent travel to undeveloped countries or the mountains, stool may be examined under the microscope for Giardia and other parasites.
• There are also immunologic tests that can be done on samples of stool to diagnose infection with Giardia.

Chronic diarrhea. With chronic diarrhea, the focus usually shifts from dehydration and infection (with the exception of Giardia, which occasionally causes chronic infections) to the diagnosis of non-infectious causes of diarrhea. (See the prior discussion of common causes of chronic diarrhea.)

• This may require X-rays of the intestines (upper gastrointestinal series or barium enema), or endoscopy (esophagogastroduodenoscopy or EGD, or colonoscopy) with biopsies.
• Fat malabsorption can be diagnosed by measuring the fat in a 72 hour collection of stool.
• Sugar malabsorption can be diagnosed by eliminating the offending sugar from the diet or by performing a hydrogen breath test. Hydrogen breath testing also can be used to diagnose bacterial overgrowth of the small intestine.
• An under-active pituitary or adrenal gland and an overactive thyroid gland can be diagnosed by measuring blood levels of cortisol and thyroid hormone, respectively.
• Celiac disease can be diagnosed with blood tests and a biopsy of the small intestine.

How can dehydration be prevented and treated?

Oral rehydration solutions (ORS) are liquids that contain a carbohydrate (glucose or rice syrup) and electrolyte (sodium, potassium, chloride, and citrate or bicarbonate). Originally, the World Health Organization (WHO) developed the WHO-ORS to rapidly rehydrate victims of the severe diarrheal illness, cholera. The WHO-ORS solution contains glucose and electrolytes. The glucose in the solution is important because it forces the small intestine to quickly absorb the fluid and the electrolytes. The purpose of the electrolytes in the solution is the prevention and treatment of electrolyte deficiencies.
In the United States, convenient, premixed commercial ORS products that are similar to the WHO-ORS are available for rehydration and prevention of dehydration. Examples of these products are Pedialyte, Rehydralyte, Infalyte, and Resol.
Most of the commercially available ORS products in the U.S. contain glucose. Infalyte is the only one that contains rice carbohydrate instead of glucose. Most doctors believe that there are no important differences in effectiveness between glucose and rice carbohydrate.
Infants and young children. Most acute diarrhea in infants and young children is due to viral gastroenteritis and is usually short-lived. Antibiotics are not routinely prescribed for viral gastroenteritis. However, fever, vomiting, and loose stools can be symptoms of other childhood infections such as otitis media (infection of the middle ear), pneumonia, bladder infection, sepsis (bacterial infection in the blood) and meningitis. These illnesses may require early antibiotic treatment.
Infants with acute diarrhea also can quickly become severely dehydrated and therefore need early rehydration. For these reasons, sick infants with diarrhea should be evaluated by their pediatricians to identify and treat underlying infections as well as to provide instructions on the proper use of oral rehydration products.
Infants with moderate to severe dehydration usually are treated with intravenous fluids in the hospital. The pediatrician may decide to treat infants who are mildly dehydrated due to viral gastroenteritis at home with ORS.
Infants that are breast-fed or formula-fed should continue to receive breast milk during the rehydration phase of their illness if not prevented by vomiting. During, and for a short time after recovering from viral gastroenteritis, babies can be lactose intolerant due to a temporary deficiency of the enzyme, lactase (necessary to digest the lactose in milk) in the small intestine. Patients with lactose intolerance can develop worsening diarrhea and cramps when dairy products are introduced. Therefore, after rehydration with ORS, an undiluted lactose-free formula and diluted juices are recommended. Milk products can be gradually increased as the baby improves.
Older children and adults. During mild cases of diarrhea, diluted fruit juices, soft drinks containing sugar, sports drinks such as Gatorade, and water can be used to prevent dehydration. Caffeine and lactose containing dairy products should be temporarily avoided since they can aggravate diarrhea, the latter primarily in individuals with transient lactose intolerance. If there is no nausea and vomiting, solid foods should be continued. Foods that usually are well tolerated during a diarrheal illness include rice, cereal, bananas, potatoes, and lactose-free products.
ORS can be used for moderately severe diarrhea that is accompanied by dehydration in children older than 10 years of age and in adults. These solutions are given at 50 ml/kg over 4-6 hours for mild dehydration or 100 ml/kg over 6 hours for moderate dehydration. After rehydration, the ORS solution can be used to maintain hydration at 100 ml to 200 ml/kg over 24 hours until the diarrhea stops. Directions on the solution label usually state the amounts that are appropriate. After rehydration, older children and adults should resume solid food as soon as any nausea and vomiting subside. Solid food should begin with rice, cereal, bananas, potatoes, and lactose free and low fat products. The variety of foods can be expanded as the diarrhea subsides.

How is diarrhea treated?

Absorbents. Absorbents are compounds that absorb water. Absorbents that are taken orally bind water in the small intestine and colon and make diarrheal stools less watery. They also may bind toxic chemicals produced by bacteria that cause the small intestine to secrete fluid; however, the importance of toxin binding in reducing diarrhea is unclear.

The two main absorbents are attapulgite and polycarbophil, and they are both available without prescriptions.

Examples of products containing attapulgite are:

• Donnagel,
• Rheaban,
• Kaopectate Advanced Formula,
• Parepectolin, and
• Diasorb.

Examples of products containing polycarbophil are:

• Equalactin,
• Konsyl Fiber,
• Mitrolan, and
• Polycarb.

Equalactin is the antidiarrheal product containing attapulgite; however the laxative, Konsyl, also contains attapulgite. Attapulgite and polycarbophil remain in the intestine and, therefore, have no side effects outside of the gastrointestinal tract. They may occasionally cause constipation and bloating. One concern is that absorbents also can bind medications and interfere with their absorption into the body. For this reason, it often is recommended that medications and absorbents be taken several hours apart so that they are physically separated within the intestine.

Anti-motility medications. Anti-motility medications are drugs that relax the muscles of the small intestine and/or the colon. Relaxation results in slower flow of intestinal contents. Slower flow allows more time for water to be absorbed from the intestine and colon and reduces the water content of stool. Cramps, due to spasm of the intestinal muscles, also are relieved by the muscular relaxation.

The two main anti-motility medications are loperamide (Imodium), which is available without a prescription, and diphenoxylate (Lomotil), which requires a prescription. Both medications are related to opiates (for example, codeine ) but neither has the pain-relieving effects of opiates.

Loperamide (Imodium), though related to opiates, does not cause addiction.

Diphenoxylate is a man-made medication that at high doses can be addictive because of its opiate-like, euphoric (mood-elevating) effects. In order to prevent abuse of diphenoxylate and addiction, a second medication, atropine, is added to loperamide in Lomotil. If too much Lomotil is ingested, unpleasant side effects from too much atropine will occur.

Loperamide and diphenoxylate are safe and well-tolerated. There are some precautions, however, that should be observed.

• Anti-motility medications should not be used without a doctor's guidance to treat diarrhea caused by moderate or severe ulcerative colitis, C. difficile colitis, and intestinal infections by bacteria that invade the intestine (for example, Shigella). Their use can lead to more serious inflammation and prolong the infections.

• Diphenoxylate can cause drowsiness or dizziness, and caution should be used if driving or performing tasks that require alertness and coordination are required.

• Anti-motility medications should not be used in children younger than two years of age.

• Most unimportant, acute diarrhea should improve within 72 hours. If symptoms do not improve or if they worsen, a doctor should be consulted before continuing treatment with anti-motility medications.

Bismuth compounds. Many bismuth-containing preparations are available around the world. Bismuth subsalicylate (Pepto-Bismol) is available in the United States. It contains two potentially active ingredients, bismuth and salicylate (aspirin). It is not clear how effective bismuth compounds are, except in traveler's diarrhea and the treatment of H. pylori infection of the stomach where they have been shown to be effective. It also is not clear how bismuth subsalicylate might work. It is thought to have some antibiotic-like properties that affect bacteria that cause diarrhea. The salicylate is anti-inflammatory and could reduce secretion of water by reducing inflammation. Bismuth also might directly reduce the secretion of water by the intestine.

Pepto-Bismol is well-tolerated. Minor side effects include darkening of the stool and tongue. There are several precautions that should be observed when using Pepto-Bismol.

• Since it contains aspirin, patients who are allergic to aspirin should not take Pepto-Bismol.

• Pepto-Bismol should not be used with other aspirin-containing medications since too much aspirin may be ingested and lead to aspirin toxicity, the most common manifestation of which is ringing in the ears.

• The aspirin in Pepto-Bismol can accentuate the effects of anticoagulants, particularly warfarin (Coumadin), and lead to excessive bleeding. It also may cause abnormal bleeding in people who have a tendency to bleed because of genetic disorders or underlying diseases, for example, cirrhosis, that may cause abnormal bleeding.

• The aspirin in Pepto-Bismol can aggravate stomach and duodenal ulcer disease.

• Pepto-Bismol and aspirin-containing products should not be given to children and teenagers with chickenpox, influenza, and other viral infections because they may cause Reye's syndrome. Reye's syndrome is a serious illness affecting primarily the liver and brain that can lead to liver failure and coma, with a mortality rate of at least 20%.

• Pepto-Bismol should not be given to infants and children younger than two years of age.

When should antibiotics be used for diarrhea?

Most episodes of diarrhea are acute and of short duration and do not require antibiotics. Antibiotics are not even necessary for the most common bacterial infections that cause diarrhea. Antibiotics, however, often are used when (1) patients have more severe and persistent diarrhea, (2) patients have additional debilitating diseases such as heart failure, lung disease, and AIDS, (3) stool examination and testing discloses parasites, more serious bacterial infections (for example, Shigella), or C. difficile, and 4) traveler's diarrhea.

Diarrhea At A Glance

• Diarrhea is an increase in the frequency of bowel movements, an increase in the looseness of stool or both.

• Diarrhea is caused by increased secretion of fluid into the intestine, reduced absorption of fluid from the intestine or rapid passage of stool through the intestine.

• Diarrhea can be defined absolutely or relatively. Absolute diarrhea is defined as more than five bowel movements a day or liquid stools. Relative diarrhea is defined as an increase in the number of bowel movements per day or an increase in the looseness of stools compared with an individual's usual bowel habit.

• Diarrhea may be either acute or chronic, and each has different causes and treatments.

• Complications of diarrhea include dehydration, electrolytes (mineral) abnormalities, and irritation of the anus.

• Dehydration can be treated with oral rehydration solutions and, if necessary, with intravenous fluids.

• Tests that are useful in the evaluation of acute diarrhea include examination of stool for white blood cells and parasites, cultures of stool for bacteria, testing of stool for the toxin of C. difficile and blood tests for electrolyte abnormalities.

• Tests that are useful in the evaluation of chronic diarrhea include examination of stool for parasites, upper gastrointestinal X-rays (UGI series), barium enema, esophago-gastro-duodenoscopy (EGD) with biopsies, colonoscopy with biopsies, hydrogen breath testing, and measurement of fat in the stool.

• Diarrhea may be treated with absorbents, anti-motility medications, and bismuth compounds.

• Antibiotics should not be used in treating diarrhea unless there is a culture-proven bacterial infection that requires antibiotics, severe diarrhea that is likely to be infectious in origin, or when an individual has serious underlying diseases.

Additional resources from WebMD Boots UK on Diarrhoea