Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at December 10, 2015

Though it isn't pleasant, diarrhea is not typically a serious condition. It generally clears up within a couple of days on its own. Most people get diarrhea a few times a year. However, some individuals may have more frequent episodes of runny stool due to conditions, such as Irritable bowel syndrome, Crohn's disease, and ulcerative colitis.


Definition & Facts

Diarrhea can be classified as either absolute or relative. Absolute diarrhea is defined as having liquid stools or more than five bowel movements in one day.

Relative diarrhea is defined as an increase in the looseness of stool or an increase in the number of bowel movements one has in a day compared to that individual's usual bowel movement habits. Diarrhea can also be acute or chronic, each having different causes and remedies.

Additionally, incontinence, the inability to control or delay bowel movements, urgency, and incomplete evacuation, the sensation that one needs to have another bowel movement shortly after having had one, can accompany diarrhea but often have different causes. Nausea, vomiting, stomach cramps, dehydration, and bloating may also accompany diarrhea.


Acute and chronic diarrhea have different causes and treatments. Acute diarrhea lasts two weeks or less. The most common cause of acute diarrhea is infection with a virus, bacteria, or parasite.

The most common viruses responsible for causing runny stool are rotavirus, enterovirus, norovirus, and hepatitis viruses. Salmonella, E. coli, clostridium, shigella, and vibrio cholerae are common bacterium responsible for loose stool.

Parasites that cause giardiasis and amebiasis may also lead to acute diarrhea. Additionally, alcohol abuse, medication, laxative abuse, food allergies, and food poisoning can also lead to acute bouts of diarrhea.

People can pick up an infectious agent from another infected individual or get it from eating or drinking contaminated food or water. Many individuals who travel to foreign countries may get what is called, “traveler's diarrhea”, most often from drinking contaminated water.

Several medical conditions are also associated with watery stool. Hyperthyroidism, an overactive thyroid, diabetes, Zollinger-Ellison syndrome, and adrenal gland disorder, for instance, are associated with diarrhea.

Additionally, lactose intolerance and celiac disease, a reaction to consuming gluten, a protein in barley, wheat, and rye, may also lead to loose stool. Certain types of rare tumors, such as pheochromocytoma and carcinoid tumors may produce diarrhea-causing hormones as well. Colorectal cancer may cause either diarrhea or constipation.

Chronic diarrhea may be caused by several digestive diseases, such as Inflammatory bowel disease, Crohn's disease, microscopic colitis, and ulcerative colitis. Irritable bowel disease may cause alternating bouts of constipation and diarrhea. Ischemic bowel disease, which may be caused by blocked arteries, may lead to bouts of bloody diarrhea.

When to see a doctor

Most bouts of diarrhea are mild and short in duration and do not need medical attention. However, there are some situations in which a doctor should be consulted. A doctor should be consulted when a person has diarrhea and a high temperature (greater than 101 degrees Fahrenheit (38,3 °C), moderate to severe stomach pain or tenderness, moderate to severe dehydration, or vomiting that prevents one from drinking fluids.

Pregnant women who experience an acute bout of diarrhea should also consult a doctor for the health of their fetuses. A doctor should also be consulted when someone has severe diarrhea that shows no improvement after 48 hours.

In addition, one should seek medical attention when experiencing diarrhea during or immediately after completing a course of antibiotics because loose stool may be an indication of an antibiotic-associated infection called Clostridium difficile. C. difficile requires medical treatment. People who develop diarrhea after traveling to developing countries or camping in the mountains should also seek medical attention and be tested for Giardia, a parasite for which there is treatment.

Those with chronic intestinal disease, such as Crohn's disease, microscopic colitis, and ulcerative colitis should also see a doctor when having a bout of diarrhea because loose stool may indicate a complication in or worsening of the underlying condition.

Infants and children who have watery stool should see a pediatrician in order for a parent to attain advice on the appropriate use of liquids to avoid or treat dehydration. Finally, individuals experiencing chronic diarrhea should consult a medical professional to determine the cause of the problem.

Treatment & Therapy

Several types of treatments exist for relieving diarrhea. Absorbents bind water in the colon and small intestine, making stool less watery. The two main absorbents available over-the-counter are polycarbophil and attapulgite. Another absorbent, psyllium, can also be utilized to treat diarrhea, but it is typically used to treat constipation.

Once taken, absorbents stay in the small intestine and do not have any side effects outside the gastrointestinal system. One should take absorbents several hours before or after taking other medications, though, as absorbents may interfere with the absorption of other medications.

Bismuth compounds, the most popular of which is Pepto-Bismol®, are another treatment option for diarrhea. Pepto-Bismol® contains two active ingredients – bismuth and salicylate. Bismuth compounds seem to be particularly effective in the treatment of traveler's diarrhea and H. pylori infection. It is thought that bismuth compounds have some antibiotic-like properties that affect bacteria responsible for causing diarrhea. Salicylate is an anti-inflammatory and may reduce the secretion of water by reducing inflammation in the small intestine.

Certain individuals should not take Pepto-Bismol®. Salicylate is a chemical related to aspirin. Thus, people who are allergic to aspirin should not take products containing salicylate. Additionally, salicylate-containing products should not be taken with other medications containing aspirin in order to avoid aspirin toxicity. Like aspirin, salicylate can aggravate the stomach.

In addition, children under the age of two should not take Pepto-Bismol®. Salicylate-containing products should never be given to children or teenagers suffering with influenza, chickenpox, or other viral infections because they may lead to Reye's syndrome. Reye's syndrome affects the liver and brain and may lead to coma and liver failure. Reye's syndrome has a mortality rate of at least 20 percent.

Anti-motility medications may also be used in the treatment of diarrhea. Anti-motility medications relax the muscles in the colon and small intestine, slowing the movement of intestinal contents. Slower movement of intestinal contents allows for more time for water to be absorbed from the small intestine and colon, reducing the water in the stool. Stomach cramps caused by spasms of the intestinal muscles are also relieved with anti-motility medications. Loperamide, which is available over-the-counter, and diphenoxylate, which requires a prescription, are the two main anti-motility medications available to treat diarrhea.

Anti-motility medications are typically well-tolerated, but some caution should be used when taking them. Children under the age of two should not be given anti-motility drugs. People with moderate to severe ulcerative colitis, C. difficile colitis, or intestinal infections caused by bacteria that invade the small intestine, such as shigella, should not use this type of medication without consulting a doctor because the medication's use may worsen inflammation and prolong the disease. Finally, diphenoxylate may cause dizziness or drowsiness, so caution should be taken when driving or doing tasks that require alertness and concentration.

Antibiotics are not usually required in the treatment of diarrhea, even when the loose stool is caused by a bacterial infection. However, there are some cases in which the use of antibiotics may be warranted. Individuals with traveler's diarrhea or those with severe and persistent loose stool, for instance, may be treated with antibiotics. Individuals with other serious conditions, such as AIDS, heart diseases, or lung diseases may also need antibiotics. Antibiotics may also be used to treat parasitic and more serious bacterial infections.

Washing one's hands thoroughly and often will help prevent viral diarrhea. Lather hands for 20 seconds before rinsing. Washing hands before and after making food, after handling uncooked meat, changing diapers, using the restroom, coughing, sneezing, and nose blowing will help prevent viral diarrhea. The use of hand sanitizer is a good alternative to hand washing when soap and water aren't available.

Prevention & Prophylaxis

To prevent diarrhea from food contamination, store food in the refrigerator immediately after cooking or reheating it. Leaving food out at room temperature encourages bacteria growth. Wash hands and food surfaces frequently during food preparation in order to avoid spreading germs from one food to another. Use the refrigerator to thaw meat rather than leaving it out on the counter to thaw.

Avoiding consuming undercooked meat and dairy products in foreign countries is one good way to prevent traveler's diarrhea. Avoid drinking tap water and ice cubes. Instead, drink bottled water or soda, beer, or wine served in its original bottle. Starting a course of antibiotics before traveling to a developing country may also help prevent bouts of traveler's diarrhea.

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