Diarrhea is, quite simply, the passage of loose or watery stools (bowel movements).  They are often quite frequent and sometimes contain fat or mucus. These loose bowel movements may be accompanied by gas.  It's more of a problem when they contain intestinal tissue or blood, or when there's also fever, vomiting or cramping pain.

The underlying reason that diarrhea occurs is that the large intestine isn't working as well as it needs to.  Usually the large intestine absorbs the extra water that comes downstream from the small intestine.  In an adult, the large intestine may filter as much as 10 quarts of fluid a day.Even when there's diarrhea,the intestine may still absorb 9 1/2 quarts.But it's that 1/2 quart of extra fluid that loosens the bowel movements.

The Causes

Typically, the different causes of diarrhea can be grouped.

  • Infections--the most frequent cause, can come from viruses, bacteria or parasites.
  • Inflammation--where the intestinal surface can't absorb and swelling causes pain and diarrhea  (in Crohn's disease and ulcerative colitis, for example).
  • Incomplete absorption--this group can be divided into problems like lactose intolerance and celiac disease where the foods that aren't absorbed go downstream and drag extra water with them; and problems like an overactive thyroid or where surgery has shortened the intestine, so that nutrients don't have time to be absorbed.
  • Irritation--certain medications can irritate the intestine or the normal bacteria that live there (the flora).  That's the case with antibiotics, and some cancer or heart medicines.  That's also the main feature of what's known as Irritable Bowel Syndrome, where the intestine goes into an often painful spasm that can then send the intestinal contents right on through.


Infections that come quickly generally leave quickly.  But when they come make sure to:

  • Rehydrate-drink plenty of fluids, especially with fruit juices and soups that have the salts your body needs to replenish.  Hydration fluids like Pedialyte or Oralyte are preferred over sugary sports drinks.
  • Gradually introduce bread, pasta, rice and potatoes that tend to slow your intestine.  You can slowly add lean meats, fruits and yogurt.  
  • Avoid spicy or greasy foods, extra sugar and even high fiber foods that create more gas.
  • Consider a probiotic, especially if it seems to be an infection.
  • And if an infection is likely, make sure to wash your hands frequently so you don't spread it.  Also be careful not to let the kids share their cups, drinks, foods or towels.  
  • If the diarrhea continues, this is known as persistent or chronic diarrhea.  Make sure you bring your child to the doctor for further evaluation and to check and see that you are accomplishing the hydration that's needed.