Infectious mononucleosis. Complexities of a common syndrome.

Infectious mononucleosis is common in adolescents and young adults. Although the syndrome is most often associated with Epstein-Barr virus, several other organisms can also cause infectious mononucleosis. Diagnosis is based on clinical findings and the presence of heterophil antibodies and atypical lymphocytes. Diagnosis may be more difficult in older adults because the presenting symptoms often differ from those seen in children. Symptoms usually resolve in 2 to 3 weeks. Treatment of uncomplicated infectious mononucleosis is supportive, but corticosteroids may be beneficial for the treatment of several complications associated with Epstein-Barr virus. Physically active patients should be counseled about the risks of splenic injury.