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Acute diarrhea is an unpleasant digestive disorder that nearly everyone experiences at one time or another. In fact, it's estimated that most Americans can expect to have diarrhea about four times every year.

The loose-stool consistency that characterizes diarrhea usually lasts a few days at most. Diarrhea often means more-frequent trips to the toilet and a greater volume of stool. Some common causes of loose, watery stools and abdominal cramps are infections from viruses, bacteria or parasites. Other causes include medications — particularly antibiotics — and artificial sweeteners.

Chronic diarrhea lasts much longer than does acute diarrhea, generally longer than four weeks. It can be a sign of a serious disorder, such as inflammatory bowel disease, or it may be due to a less serious condition, such as irritable bowel syndrome. Chronic or recurrent diarrhea may signal poor absorption of nutrients (malabsorption).

Diarrhea may cause a loss of significant amounts of water and salts. Most cases of diarrhea clear on their own without treatment. But if diarrhea persists, you become dehydrated or you pass blood in your stool, see your doctor.

Signs and symptoms associated with diarrhea may include:

• Frequent, loose, watery stools
• Abdominal cramps
• Abdominal pain
• Fever
• Blood in the stool
• Bloating

In addition, other signs and symptoms such as nausea and vomiting may precede diarrhea that's caused by, for example, an infection. Bacterial or parasitic infections sometimes cause bloody stools, and fever may accompany these infections as well.

Normally, the food you eat remains in liquid form during most of the digestive process. When the unabsorbed food residue passes through your colon, most of the fluids are absorbed and what remains is a semisolid stool.

In diarrhea, the food and fluids you ingest pass too quickly or in too large an amount — or both — through your colon. The fluids aren't sufficiently absorbed, and the result is a watery bowel movement. In addition, the lining of your colon may be inflamed or diseased, making it less able to absorb fluids.

The most common causes of diarrhea include:

• Viruses. Common viruses that cause diarrhea are the Norwalk virus, cytomegalovirus, viral hepatitis and the herpes simplex virus. Rotavirus is the most common cause of acute childhood diarrhea. Viral diarrhea spreads easily.
• Bacteria and parasites. Contaminated food or water can transmit bacteria and parasites to your body. Parasites such as Giardia lamblia and cryptosporidium can cause diarrhea. Common bacterial causes of diarrhea include campylobacter, salmonella, shigella and Escherichia coli. This type of diarrhea can be common for people traveling to developing countries.

Other causes

• Lactose. A sugar found in milk and milk products, lactose is a common cause of diarrhea in some people.
• Medications. Diarrhea can also be a side effect of many medications, particularly antibiotics. Antibiotics destroy both good and bad bacteria, which can disturb the natural balance of bacteria in your intestines. This disturbance sometimes leads to an infection with bacteria called Clostridium difficile, which can also cause diarrhea.
• Artificial sweeteners. Sorbitol and mannitol, artificial sweeteners found in chewing gum and other sugar-free products, can cause diarrhea in some otherwise healthy people.
• Surgery. Some people may experience diarrhea after undergoing abdominal surgery or gallbladder removal surgery.
• Other digestive disorders. Chronic diarrhea has a number of other causes, such as Crohn's disease, ulcerative colitis, celiac disease and irritable bowel syndrome.

If diarrhea persists beyond five days or if you become dehydrated — as evidenced by excessive thirst, dry mouth or skin, little or no urination, severe weakness, dizziness or lightheadedness, or dark-colored urine — see your doctor. Also get medical help if you have severe abdominal or rectal pain, bloody or black stools, a temperature of more than 101 F, or signs of dehydration despite drinking plenty of liquids.

In young children, diarrhea can quickly lead to dehydration. Call your doctor if diarrhea persists for more than 24 to 48 hours or if your baby:

• Hasn't had a wet diaper in three or more hours
• Has a high fever
• Has bloody or black stools
• Has a dry mouth or cries without tears
• Is unusually sleepy, drowsy, unresponsive or irritable
• Has a sunken appearance to the abdomen, eyes or cheeks
• Has skin that doesn't flatten if pinched and released

If you have diarrhea that requires medical attention, your doctor will ask about your symptoms and will want to determine if you're dehydrated. Tell your doctor about any medications you're taking, including over-the-counter medications — they may have caused the diarrhea.

Your doctor may examine your abdomen to determine the location of your pain, may listen to your abdomen with a stethoscope and may perform a rectal exam. Your doctor may suggest blood or stool tests to check for signs of infection or other abnormalities.

Most cases of diarrhea clear on their own within a few days without treatment. If you seek medical attention, your doctor likely will advise you to take steps to replace the fluids and salts lost during diarrhea.

Your body needs adequate levels of salts and electrolytes — minerals such as sodium and potassium — in order to maintain the electric currents that keep your heart beating. Disruption of your body's fluid and mineral levels creates an electrolyte imbalance. Unless restored by replacing fluids and drinking an electrolyte mixture, this imbalance can be serious.

If your doctor determines that an antibiotic medication caused your diarrhea, you'll need to stop taking that medication and modify your treatment plan.

If a parasitic infection caused your diarrhea, prescription antibiotics may ease your symptoms. Antibiotics sometimes, but not always, help ease signs and symptoms of bacterial diarrhea. However, antibiotics won't help viral diarrhea.

If you have chronic diarrhea, treating the underlying disease may help ease your diarrhea.

You can help prevent the spread of viral diarrhea by washing your hands and encouraging your children to wash their hands. Because viral diarrhea spreads easily, it's a good idea to keep your children home from school or child care if they have diarrhea.

To guard against diarrhea caused by contaminated food:

• Use dairy products that have been pasteurized. Pasteurization involves heating dairy products for a period of time to kill bacteria.
• Serve food right away or refrigerate it after it has been cooked or reheated. Leaving food out at room temperature can encourage growth of bacteria.

Diarrhea commonly affects people who travel to developing countries, where it is sometimes due to inadequate sanitation and contaminated food and water. To reduce your risk:

• Watch what you eat. Eat hot, well-cooked foods. Avoid raw fruits and vegetables unless you can peel them yourself. Also avoid raw or undercooked meats and dairy foods.
• Watch what you drink. Drink bottled water, soda, beer or wine served in its original container. Avoid tap water and ice cubes. Use bottled water even for brushing your teeth. Keep your mouth closed while you shower. Beverages from boiled water, such as coffee and tea, are usually safe. Remember that alcohol and caffeine can aggravate diarrhea and dehydration.
• Ask your doctor about using antibiotics or bismuth subsalicylate (Pepto-Bismol) to prevent diarrhea if you're traveling to a developing country. Either type of medication, but particularly antibiotics, can significantly reduce the odds that you'll develop traveler's diarrhea.

Diarrhea caused by viral infections typically ends on its own without antibiotics. Over-the-counter (OTC) anti-diarrheal medications may slow diarrhea, but they won't speed your recovery. Certain infections may be made worse by these OTC medications because they prevent your body from getting rid of what's causing the diarrhea. Also, these drugs aren't always safe for children. Check with your doctor before giving these medications to your child.

Take these measures to prevent dehydration and reduce symptoms while you recover:

• Drink plenty of clear liquids , including water, clear sodas and broths, gelatin, and juices every day. But, avoid apple and pear juices until you feel better because they can make your diarrhea worse. Avoid caffeine and alcohol.
• Add semisolid and low-fiber foods gradually as your bowel movements return to normal. Try soda crackers, toast, eggs, rice or chicken.
• Avoid certain foods such as dairy products, fatty foods, high-fiber foods or highly seasoned foods for a few days.