Diarrhea

Diarrhea (or diarrhoea) is when a person has at least three loose, watery, or liquid bowel movements in a single day. The episode usually goes on for a few days and can lead to dehydration because the body loses fluids.

Early signs of dehydration include skin that has lost its normal stretchiness and irritable behavior. As it gets worse, a person may urinate less, have paler skin, a faster heart rate, and become less responsive. In babies who are exclusively breastfed, loose but not watery stools are normal.

The most common cause is an infection of the intestines—called gastroenteritis—from a virus, bacterium, or parasite. These infections often come from food or water contaminated with feces, or from direct contact with an infected person. There are three types: short-duration watery diarrhea, short-duration bloody diarrhea, and persistent diarrhea (lasting more than two weeks, which can be watery or bloody). Short-duration watery diarrhea can be caused by cholera, though this is rare in developed countries.

When blood is present, it is called dysentery. Non-infectious causes include lactose intolerance, drug withdrawal side effects, irritable bowel syndrome, non-celiac gluten sensitivity, celiac disease, inflammatory bowel diseases like ulcerative colitis, hyperthyroidism, bile acid diarrhea, and certain medications. In most cases, stool cultures to identify the exact cause are not needed.

Prevention includes better sanitation, clean drinking water, hand washing with soap, breastfeeding for at least six months, and rotavirus vaccination. The main treatment is oral rehydration solution (ORS)—clean water with small amounts of salts and sugar. Zinc tablets are also recommended.

These treatments have saved an estimated 50 million children over the past 25 years. People with diarrhea should keep eating healthy food, and babies should continue breastfeeding. If commercial ORS is unavailable, homemade solutions can be used.

Severe dehydration may require intravenous fluids, but most cases can be managed with fluids by mouth. Antibiotics are rarely used but may be recommended for bloody diarrhea with high fever, severe diarrhea after travel, or when specific bacteria or parasites are found in the stool. Loperamide can reduce the number of bowel movements but is not advised for severe cases.

Epidemiology

About 1.7 to 5 billion cases of diarrhea occur each year.