Mononucleosis (also called “mono”) is an illness, caused by infection with the Epstein-Barr virus, that most often affects young adults. Symptoms of mononucleosis include high fever, sore throat, swollen lymph nodes (glands), and fatigue.

Symptoms tend to be mild in young children and worse in teens and adults. The illness also causes the spleen (an organ in the abdomen) to swell, so a person who has mono needs to avoid activities that could injure the abdomen.

Mono is usually a mild illness that goes away without treatment after several weeks. During this time, symptoms may come and go and may change with time. It is normal for the lymph nodes to remain enlarged for up to a month. Fatigue that makes normal activities difficult or impossible may linger for 2 to 3 months. There is no specific treatment except rest, plenty of fluids, and nonprescription pain relievers, such as acetaminophen (Tylenol) and ibuprofen (Motrin, Advil), for body aches. Aspirin should not be given to anyone younger than age 20 because its use has been linked to Reye's syndrome, a serious illness.

Last Updated: September 8, 2009

Author: Maria Essig

Medical Review: Michael J. Sexton, MD - Pediatrics & W. David Colby IV, MSc, MD, FRCPC - Infectious Disease

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