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As masks come down and crowd sizes slowly increase, some common contagious diseases we have been able to avoid for the past couple of years are making a comeback.

Infectious mononucleosis—commonly called “the kissing disease" because of how easily it spreads through contact with saliva—is one of them. But what exactly is infectious mononucleosis? Here's a refresher. 

What is infectious mononucleosis?

Infectious mononucleosis, or “mono" for short, is a contagious disease caused by a virus. Usually, that is the Epstein-Barr virus (EBV), a member of the herpes family, explains Carolyn Mudry, DO, an internal medicine physician at Summit Health.

Who gets mono?

"Typically, it spreads among children and teens. Most people have it by adulthood and will have antibodies present on blood testing," says Dr. Mudry.

Teenagers and college students are most at risk, given their behavior and close contact in schools. According to the Centers for Disease Control and Prevention, one in four young people who are infected with EBV will get mono.

"However, adults can get it at any age if not previously exposed," Dr. Mudry adds. “Viruses don't distinguish between individuals. And the transmission is not limited to saliva. You can pass EBV and other mono-causing viruses through contact with blood or semen, transfusions, and organ transplants.”


"The incubation period is four to six weeks from exposure but may be shorter in kids," Dr. Mudry says.

After you come into contact with someone who has mono, you might start to feel inordinately tired. Aside from fatigue, other symptoms include:

  • Swollen lymph nodes in the neck and armpits
  • Sore throat
  • Fever
  • Aches and pains
  • Headache
  • Poor appetite
  • Rash
  • Swollen spleen
  • Swollen liver

Not all symptoms begin and end at the same time, and not everyone will develop every symptom. Sometimes the spleen and liver remain uninvolved.

Dr. Mudry also says, "Some can be asymptomatic and never know they had EBV."

If you are diagnosed and play a contact sport, however, physicians advise you refrain until your organs are completely back to normal, which may take several weeks or even months after the other symptoms disappear. Even for those who don't play sports, Dr. Mudry recommends avoiding significant physical activity for about three weeks. In addition, strenuous contact sports and activities that increase abdominal pressure, such as football and gymnastics, may need longer periods of rest before resumption. She adds, “Fatigue can be persistent and can sometimes last a few months."


Dr. Mudry explains that serious complications are not common but include:

  • Enlarged spleen
  • Kidney failure
  • Cardiac and neuro complications
  • Compromised airway if the tonsils overly enlarge 

Complications are most likely to occur in immunocompromised individuals. "The vast majority of people recover well in a few weeks," she notes.


There's very little treatment for mono itself, other than how you would normally treat a virus.

Dr. Mudry recommends bed rest, lots of fluids, and over-the-counter pain relievers and fever reducers.  

For serious or lingering mono infections, especially in immunocompromised or high-risk patients, physicians might prescribe antivirals that target the underlying EBV. Those are administered intravenously or in pill form. 


You can prevent spreading mono by refusing to share drinks or food, using barrier methods of protection during sex, and washing your hands after touching personal items.