Mono is caused by the Epstein-Barr virus (EBV). It is passed from person to person through contact with someone else's saliva, such as through:

  • Intimate behavior, such as kissing
  • Sharing food or drinks

Risk Factors

Many people get EBV during their lifetime. Things that raise the risk that EBV will turn into mono are:

  • Getting EBV after age 10
  • Lowered immune system due to other illness, stress, or lack of energy
  • Living in close quarters with many people, such as in a college dorm

Getting mono once means a person will be immune to it in the future.



Signs of mono start four to seven weeks after a person was exposed to the virus. The first symptoms may be a sense of weakness that lasts about one week. Next, a person may have:

  • High fever
  • Severe sore throat
  • Swollen glands
  • Lack of energy
  • Loss of hunger
  • Muscle aches
  • Belly swelling
  • Yellowing of the skin and whites of the eyes


The doctor will ask about symptoms and past health. A physical exam will be done.

Blood tests may be done to look for signs of infection.



There is no way to cure mono or to shorten how long the illness lasts. It lasts 4 to 6 weeks, but the lack of energy may last longer.

The goal is to manage symptoms. Choices are:

  • Lifestyle changes, such as limiting contact sports and heavy lifting to avoid injury to a swollen spleen
  • Supportive care, such as getting rest, drinking plenty of fluids, and gargling with salt water
  • Medicines to ease pain and swelling in the throat, such as pain relievers or steroids


To lower the risk of this problem:

  • Avoid contact with anyone who has active mono.
  • Do not share drinks or food with anyone who may be sick.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.