Diarrhea is a symptom, not a disease. It is defined as passing frequent loose stools. The acute form lasts only a day or two and usually isn't serious, but it can be linked with some other problems. It affects people of all ages, and some types are infectious. The average person may get acute diarrhea 3 to 5 times a year, and long-term effects are rare. Children under five years of age experience about 1 to 3 episodes of diarrhea yearly.

Chronic diarrhea lasts longer than 2 weeks, or shows up as repeated episodes of diarrhea lasting less than 2 weeks each. An inflammatory bowel condition such as ulcerative colitis or Crohn's disease may be to blame.

This article explains symptoms and recommended treatments for adults. Children and infants with diarrhea should be seen by a doctor.

People get diarrhea when the feces move too quickly through the bowels so that the intestines don't have enough time to pull water from the waste to "firm it up."

People get diarrhea for many reasons, including:

• not digesting food completely - for example, some people can't digest lactose, the sugar found in milk. Others may not be able to digest or absorb fat or carbohydrates.
• certain intestinal diseases such as ulcerative colitis and Crohn's disease
• bacterial and viral infections such as salmonella or rotavirus, the most common cause of transient diarrhea in children
• intestinal parasites, especially when traveling
• certain medications, such as blood pressure medications and those containing magnesium
• radiation or chemotherapy

In functional bowel disorders like irritable bowel syndrome, the muscles that normally move waste along the intestine can spasm causing diarrhea.

If you think that a medication you're taking is causing the problem, don't stop taking it before talking to your doctor.

Diarrhea isn't always due to things that are eaten or swallowed - emotional stress or turmoil can also bring it on.

Your stool will be loose and watery. You may suffer from abdominal cramping and even have a fever, along with chills. If you've had diarrhea for a few days, you may feel lightheaded or weak. This comes from rapidly losing the minerals, sugar, and water that your body needs. Normally, diarrhea won't cause you to lose control of your bowels; if this happens, you should consult your doctor.

You may notice that you're urinating less. This is because your body is losing water through bowel movements instead of urine. If the diarrhea lasts longer than 48 hours or you have a fever of 38.5ºC or higher, or have severe abdominal pain or vomiting that prevents fluid replacement by mouth, see a doctor immediately. Acute diarrhea accompanied by fever and stools with blood can be signs of a potentially dangerous infection or parasite. Always consult a doctor for a child with diarrhea who hasn't urinated for six hours - the child could be dangerously dehydrated.

Your doctor will first need to find out what's causing your diarrhea by asking questions about your eating habits and medication you've been taking (including nonprescription medication). Blood and stool samples may be taken to check for infection if deemed necessary. It may take several days to get the results of stool samples, but it is important for your doctor to know what is causing the diarrhea to determine the appropriate treatment.

With chronic diarrhea, a colonoscopy may need to be done to be sure it isn't due to more serious problems. This involves inserting a flexible tube with a tiny camera in the tip (an endoscope) by way of the anus to examine the inside of the colon (the last part of the intestines).

The goal of treatment is to ease the symptoms and get the bowel movements back to normal. Preventing dehydration, which can happen due to the extra loss of water during episodes of diarrhea, is also important, especially in children and seniors.

People don't always need to take medication for diarrhea. For adults, if possible it's a good idea to just wait 48 to 72 hours to see if it stops on its own. By allowing it to "run its course," your body can naturally get rid of the diarrhea and whatever caused it. If the diarrhea continues, however, you should talk to your doctor. If the suspected cause is a parasite or bacteria, your doctor may prescribe an antibiotic to get rid of it. Otherwise, a doctor or pharmacist may recommend medications such as attapulgite, bismuth subsalicylate, loperamide*, or psyllium to provide relief from debilitating symptoms. If symptoms continue more than 48 hours from onset of the diarrhea, consult a doctor.

Dehydration caused by losing water through frequent bowel movements can cause serious complications. In particular, it can make any medications you take go through your body much more quickly than they should, so they may not work properly. Be sure to discuss this with your doctor. Signs of dehydration include a dry mouth, increased thirst, decreased urination, and feeling weak or light-headed. Signs may also include nausea, muscle cramps, and a higher body temperature. At the first sign of diarrhea, drink plenty of "clear" fluids, at least two cups an hour. Oral rehydration solutions designed to best match the body's intestinal fluid are best, especially for children and seniors. Be sure to consult a health professional before treating children or if diarrhea is accompanied by vomiting. Once rehydration has been successful, age-appropriate foods should be re-introduced. Standard recommendations no longer include "resting the bowel" after a diarrhea episode. Take it easy physically until the diarrhea is gone - you'll need your strength to get well faster.

Find out what caused your diarrhea - you may be able to prevent it in the future. Because infectious agents cause so many cases, take the same precautions with diarrhea as with the flu:

• Don't touch the hands of someone with diarrhea. If you must touch them, wash your hands immediately afterwards.
• If you have diarrhea, wash your hands before making meals and after using the washroom, and dry your hands with a disposable paper towel, not the towel everyone else uses.
• Many of the infectious agents that cause diarrhea hide out in food. Avoid eating undercooked meat or raw seafood, and watch out for foods that are past their freshness date or have been left in the open.

*All medications have both common (generic) and brand names. The brand name is what a specific manufacturer calls the product (e.g., Tylenol^®). The common name is the medical name for the medication (e.g., acetaminophen). A medication may have many brand names, but only one common name. This article lists medications by their common names. For more information on brand names, speak with your doctor or pharmacist.