Diarrhea Diagnosis

How is the cause of diarrhea diagnosed?
If acute diarrhea lasts 2 days or less, diagnostic tests are usually not necessary. If diarrhea lasts longer or is accompanied by symptoms such as fever or bloody stools, a doctor may perform tests to determine the cause.

Diagnostic tests to find the cause of diarrhea may include the following:

  • Medical history and physical examination: Dr. Jones will ask about eating habits and medication use and will perform a physical examination to look for signs of illness.
  • Stool culture: A sample of stool is analyzed in a laboratory to check for bacteria, parasites, or other signs of disease and infection.
  • Blood tests: Blood tests can be helpful in ruling out certain diseases.
  • Fasting tests: To find out if a food intolerance or allergy is causing the diarrhea, Dr. Jones may ask a person to avoid foods with lactose, carbohydrates, wheat, or other ingredients to see whether the diarrhea responds to a change in diet.
  • Sigmoidoscopy or colonoscopy: These tests may be used to look for signs of intestinal diseases that cause chronic diarrhea.