Infectious mononucleosis is an extremely common problem in the athletic population. "Mono" occurs in 3% of college students. Diagnosing infectious mononucleosis requires an understanding of the clinical features such as fever, lymphadenopathy, pharyngitis, and splenomegaly, as well as laboratory findings. The time at which these clinical features and laboratory abnormalities develop is also important to understand. Splenomegaly is common, but splenic rupture is very rare. Whether an athlete may return to activity usually relates to the presence of splenomegaly and the duration of the illness. Splenic rupture has not been reported after an individual has been ill for more than 3 weeks. This article provides an overview of infectious mononucleosis. The most common complications are reviewed and the management of these problems discussed. A practical approach to determining when an athlete may return to activity is presented.
