How much activity is safe with mononucleosis?
Ask the doctor
Q. To what extent should a person who has been diagnosed with infectious mononucleosis limit physical activities? And for how long? I know to avoid contact sports, but what about swimming?
A. As you say, a person who has been diagnosed with infectious mononucleosis ("mono") should avoid any kind of activity that could cause injury to the belly. Why? Because mono often causes a temporary enlargement of the spleen. A normal-sized spleen generally lies underneath the lower part of the rib cage, on the left side of the body. Here it is protected against blows to the chest or abdomen. However, an enlarged spleen pushes into the abdomen where there is no hard covering (like the ribs) to protect it against physical injury.
If an enlarged spleen is injured, it can rupture, causing serious — even life-threatening — bleeding. It can be hard for a doctor to tell whether the spleen is enlarged in a person with mono. As you mention, you should continue to avoid contact sports until your doctor says you can. I suspect your doctor will recommend waiting until
- at least three to four weeks have elapsed since they became sick
AND
- there is no sign of an enlarged spleen, fever, or swollen glands (in their neck, under their arms, or in their groin).
What about activities that don't raise the risk of physical injury to the abdomen? Most doctors would tell you the same thing that your grandmother would: don't start exercising until you feel that you are back to normal. That means your energy and appetite are back, and your fever and swollen glands have gone away. Swimming at a slow pace could be a great way to start back into an exercise program.
Mind you, we don't have a lot of scientific data to support that advice: We cannot say for sure that you risk harming yourself if you return to vigorous non-contact sports before you feel you've recovered. It just makes sense that you might. Mono is a viral infection, and the immune system needs a lot of energy to fight it.
Image: © Fiordaliso/Getty Images
About the Author
Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
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