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Diarrhea

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:

 

  • 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.
  • 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.
  • 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.
  • bowel movements immediately after eating a meal.

Symptoms

Diarrhea may be accompanied by cramping, abdominal pain, nausea, an urgent need to use the bathroom, or loss of bowel control. Some infections that cause diarrhea can also cause a fever and chills or bloody stools.

 

The common illness, which may last several days, often called "intestinal flu", is often due to one of a number of viruses that infect the bowel, making it weep fluid. The excess of fluid in the bowel leads to liquid stools. The inflammation may also be associated with cramping abdominal pain, nausea, and vomiting.

 

Other common infectious diarrheas may be caused by bacteria. These bacteria irritate the bowel and make it pour out fluid. The inflammation may also be associated with cramping abdominal pain. "Travelers' diarrhea" is due to particular bacteria common in certain areas of the world.

Causes

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 genusnorovirus 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. colicause 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),
  • 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),
  • 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.

Treatment

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 attapulgiteare:

 

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

 

Examples of products containing polycarbophil are:

 

  • Equalactin,
  • Konsyl Fiber,
  • Mitrolan,
  • 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.

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