Can mononucleosis come back? I thought that once you get mono you can't get it again.

Most people who have mononucleosis, also called mono, will have it only once. The disease often goes away in 2 to 4 weeks after causing symptoms such as fever and fatigue.

Mono is caused by a viral infection. Most cases of mononucleosis are caused by the Epstein-Barr virus (EBV). Once you catch the virus, you carry it for the rest of your life.

Some studies suggest that it's possible to get mononucleosis again after you recover from mono linked to EBV. More research is needed to understand the extent, if any, that this happens in otherwise healthy adults. But overall, it's highly unlikely to happen. Most people will never have another bout of mono caused by EBV.

After you recover from mononucleosis caused by EBV, it's possible to get mono again from a different source. It doesn't come back, but instead is a new infection. Some causes of mono other than EBV are:

  • Cytomegalovirus.
  • Toxoplasmosis.
  • HIV.
  • Rubella.
  • Hepatitis A, B or C.
  • Adenovirus.

Talk to your health care provider if you've had mononucleosis before and you think you have symptoms of it again. Mono symptoms can include:

  • Extreme tiredness.
  • Head and body aches.
  • Fever.
  • Sore throat.
  • Swollen lymph nodes in the neck and underarms.
  • Rash.

Other illnesses can cause these symptoms as well. See your health care provider to get diagnosed.

If you do have mono, your provider may suggest you avoid sports. This is because the spleen can swell during a mono infection. And a swollen spleen can be damaged by pressure on the stomach during sports.

This could happen during a contact sport. It could happen in a sport where the stomach presses on something, such as an uneven bar in gymnastics. It also could happen when stomach muscles are used, as in weightlifting.


Pritish K. Tosh, M.D.

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Feb. 11, 2023 See more Expert Answers