How is diarrhea diagnosed?

Lawrence S. Friedman, MD
During a diarrhea diagnosis, the doctor will ask questions about your symptoms and try to determine whether the diarrhea is chronic, or whether it's the result of a virus or bacterium and thus likely to be short-lived. If it's chronic, the doctor will want to probe further to establish whether the diarrhea is due to an organic problem or whether it's functional. You may be asked questions about your habits, including drug or alcohol use. Alcohol abuse commonly results in diarrhea, as does use of certain drugs, including cocaine.

The doctor will probably ask questions such as these:
  • When did the diarrhea start?
  • Have any other family members been sick?
  • Have you recently traveled out of the country?
  • Are you having abdominal pain? Fever? Chills?
  • Is there blood in the stool?
  • Is it worse when you are under stress?
  • Do any specific foods make it worse?
  • Do you drink coffee? Alcohol?
  • What medications are you taking or have you taken recently?
If blood or pus in the stool accompanies diarrhea, or if there is fever, anemia, profound loss of appetite, or severe vomiting, it's not functional diarrhea.

For most people and for most mild episodes of diarrhea, no specific lab tests are required. But for more severe cases, or when symptoms of inflammation are present, the doctor will order stool tests to look for the presence of certain bacteria or parasites.

Blood can be drawn to test for hemoglobin, white blood cell count, and sedimentation rate. A sigmoidoscopy may also be performed. For people over 40, a colonoscopy or a barium enema may be ordered to check for organic diseases. Doctors must exclude the possibility of Crohn's disease, ulcerative colitis, or other serious illness, such as colon cancer. These are usually accompanied by blood in the stool, fever, or weight loss.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.