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Mononucleosis(Infectious Mononucleosis; Mono)

Mononucleosis is an infectious disease that is associated with fever, fatigue, and swollen lymph glands.

Swollen Glands

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Mononucleosis is caused by the Epstein-Barr virus (EBV). Found mainly in saliva and mucus, EBV is passed from person to person by intimate behavior, such as kissing.

Risk Factors

Many people get EBV during their lifetime. Factors that increase the likelihood that EBV will develop into mononucleosis include:

  • Contracting EBV after age 10
  • Lowered immune resistance due to other illness, stress, or fatigue
  • Living in close quarters with a large number of people, such as in a college dormitory

One episode of mononucleosis usually produces permanent immunity.


Signs of mononucleosis usually begin 4-7 weeks after you were exposed to the virus. The initial symptoms may be a sense of general weakness that lasts about 1 week. This is followed by symptoms that may include:

  • High fever
  • Severe sore throat/swollen tonsils
  • Swelling of the lymph nodes
  • Fatigue
  • Loss of appetite
  • Muscle aches
  • Abdominal swelling
  • Yellowing of the skin and whites of the eyes— jaundice

You will be asked about your symptoms and medical history. A physical exam will be done.

Your bodily fluids may be tested. This can be done with blood tests.


There is no treatment to cure mononucleosis or to shorten the length of the illness. It usually runs its course in 4-6 weeks, although the fatigue may last longer.

During the first few weeks after diagnosis, you should avoid contact sports and lifting anything heavy. Inflammation of the spleen from mononucleosis puts you at high risk of splenic rupture. This can require surgery. In rare cases, it can be fatal.

It is important to get plenty of rest. Other supportive care may involve:

  • Over-the-counter pain relievers, such as ibuprofen
  • Gargling with warm, salty water
  • Steroids to reduce inflammation in the throat
  • Drinking plenty of fluids

Most people contract the EBV virus sometime during their lives. Prevention is geared toward decreasing the likelihood that EBV will develop into mononucleosis. This can be done by:

  • Avoiding intimate contact, especially kissing, with anyone who has active mononucleosis
  • Eating a healthful diet
  • Avoiding excess stress
  • Getting enough rest


Centers for Disease Control and Prevention

National Institute of Allergy and Infectious Diseases


About Kids Health—The Hospital for Sick Children

The College of Family Physicians of Canada


Balfour HH Jr, Hokanson KM, et al. A virologic pilot study of valacyclovir in infectious mononucleosis. J Clin Virol. 2007;39:16-21.

Epstein-Barr virus-associated mononucleosis. EBSCO DynaMed website. Available at: Updated May 11, 2015. Accessed June 9, 2015.

Luzuriaga K, Sullivan JL. Infectious mononucleosis. N Engl J Med. 2010 May 27;362(21):1993-2000.

Mononucleosis. Academy of Family Physicians Family Doctor website. Available at: Updated March 2014. Accessed June 9, 2015.

Last reviewed June 2015 by Fabienne Daguilh, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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