Physical exam

Your doctor may suspect mononucleosis based on your signs and symptoms, how long they've lasted and a physical examination. He or she will look for signs like swollen lymph nodes, tonsils, liver or spleen, and consider how these signs relate to the symptoms you describe.

Blood tests

  • Antibody tests. If there's a need for additional confirmation, a monospot test may be done to check your blood for antibodies to the Epstein-Barr virus. This screening test gives results within a day. But it may not detect the infection during the first week of the illness. A different antibody test requires a longer result time, but can detect the disease even within the first week of symptoms.
  • White blood cell count. Your doctor may use other blood tests to look for an elevated number of white blood cells (lymphocytes) or abnormal-looking lymphocytes. These blood tests won't confirm mononucleosis, but they may suggest it as a possibility.
Dec. 11, 2015
  1. AskMayoExpert. Epstein-Barr virus infection. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2014.
  2. Sullivan JL. Clinical manifestations and treatment of Epstein-Barr virus infection. http://www.uptodate.com/home. Accessed Oct. 26, 2015.
  3. Aronson MD, et al. Infectious mononucleosis in adults and adolescents. http://www.uptodate.com/home. Accessed Oct. 26, 2015.
  4. Epstein-Barr virus and infectious mononucleosis. Centers for Disease Control and Prevention. http://www.cdc.gov/epstein-barr/index.html. Accessed Oct. 26, 2015.
  5. Infectious mononucleosis. Merck Manual Professional Version. http://www.merckmanuals.com/professional/infectious-diseases/herpesviruses/infectious-mononucleosis. Accessed Oct. 26, 2015.
  6. Reye's syndrome information page. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/reyes_syndrome/reyes_syndrome.htm. Accessed Oct. 26, 2015.