If I had mononucleosis 5 years ago, can I still give it to someone? I kissed this guy 4 days ago, and he is saying that I gave him mono already! Is this possible?
– Jada*

Although the virus that causes mono stays in the body for the rest of a person's life, that person does not stay contagious forever. Experts believe that people are most contagious from right before their mono symptoms start until the symptoms go away. Most doctors recommend that people avoid kissing or sharing utensils for about 6 months after they feel better. It's very unlikely that a person is still contagious 5 years after symptoms are gone.

So chances are you didn't give your guy mono. Another clue that he didn't get the infection from you is that it usually takes 30–50 days after infection for the symptoms of mono to show up — not 4 days!

For more information, check out these articles:
How Long Is Mono Contagious?
Mononucleosis
Can a Person Get Mono More Than Once?

Reviewed by: Larissa Hirsch, MD
Date reviewed: September 2006

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*Names have been changed to protect user privacy.