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  • Definition

    Most people experience frequent, watery bowel movements once or twice a year. This change from the usual pattern of stools is recognized as diarrhea, although many less "formal" names are sometimes used.


    For most people, the episode is more an inconvenience than an illness. Symptoms commonly disappear in a short time, and the only important effect is that water and salts are lost from the body.

    Sometimes diarrhea lasts for weeks or months, and then it can be an indication of major disease. This more serious form of diarrhea may be accompanied by blood, mucus, or undigested food in the stools.

    The underlying cause of diarrhea also may produce fever, abdominal cramps, weight loss, nausea, and/or vomiting. So, we should try to separate the mild and short-lived episodes of diarrhea from continuous and severe diarrhea with these other features.

    People living in certain areas are usually well adjusted to commonly found bacteria in their environment, but people who are new arrivals are susceptible to these bacterial infections.

    Although most infectious diarrheas are brief illnesses, some do not go away after a few days. More serious forms can be caused by microbes such as amoebae and giardia, which can become established in the bowel and cause problems that persist for weeks or months. Contaminated food or water, public swimming pools, and communal hot tubs are possible sources of these infections.

    Infectious diarrhea can have serious consequences in certain persons. Young infants, very old people, or those who have major illnesses can be seriously weakened by even a minor infection. Simple infectious diarrhea is still a major killer in underdeveloped countries, where infections of the bowel are estimated to cause millions of deaths annually among infants.


    A hundred or more different diseases can be associated with diarrhea. Fortunately, most of the severe causes are rare and the most common form is the one that affects most of us for a few days each year. It is due to a simple infection, usually caused by a virus.

    Bacterial infections can cause more serious cases of diarrhea as a result of eating contaminated food or drinks (food poisoning). Common bacteria are campylobacter, salmonellae, and shigella organisms; less common are Escherichia coli (E coli), yersinial, listerial, and cryptosporidial bacteria. These can cause fairly severe diarrhea with vomiting, abdominal cramping and fever.

    The more serious causes include ulcerative colitis (when blood is usually present in the stools), regional ileitis (crohn's disease), some forms of intestinal cancer (when pain and weight loss might also be present), and some disorders of the intestine that lead to poor digestion of food.

    "Nervous diarrhea," in its more severe form a component of irritable bowel syndrome (IBS), is very common and often shows up briefly when we face the stress of a term paper or a job interview. However, some people suffer nervous stress fairly constantly and may have continuous diarrhea because of it.


    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.


    When diarrhea is present, how long until seeing a doctor?

    What other symptoms would make me need to see a doctor?

    What are the symptoms of dehydration in the baby? In the adult? How do I treat dehydration while at home?

    What and when are medicines used for diarrhea?

    What are the side effects of medications used for diarrhea?

    Is there any special hygiene techniques that should be practiced when traveling?

    Can I prevent Travelers’ diarrhea?