Diarrhea

Diarrhea is defined as the passage of three or more loose or watery stools within 24 hours, often with urgency, cramps, and sometimes nausea. It is a common symptom that can be acute, lasting a few days, or chronic, lasting several weeks or longer. Acute diarrhea usually results from infection, medication, or a dietary change; persistent diarrhea lasts 14–28 days; chronic diarrhea lasts more than four weeks.

Common causes include viral infections such as norovirus and rotavirus, bacterial infections such as Salmonella or Campylobacter, and parasites such as Giardia. Noninfectious causes include lactose intolerance, malabsorption, inflammatory bowel disease, irritable bowel syndrome, medications (particularly antibiotics and certain laxatives), and contamination of food or water. Travelers’ diarrhea is a well-known form caused by enteric pathogens.

Symptoms may include loose stools, cramping abdominal pain, urgency, bloating, nausea, fever, or blood in the stool. Dehydration is a key complication, especially in young children and older adults, and can lead to electrolyte disturbances and reduced kidney function.

Diagnosis relies on history and examination; stool studies, blood tests, and imaging are used when stools are persistent, severe, or accompanied by fever or dehydration. In persistent diarrhea, endoscopy or colonoscopy may be needed to assess the bowel.

Treatment focuses on rehydration, usually with oral rehydration solution, and maintaining nutrition. Zinc supplementation is recommended for children in many settings. Antibiotics are used selectively, depending on the suspected or confirmed cause. Prevention includes good hand hygiene, safe food and water, vaccination against rotavirus, and prudent antibiotic use.