I Had Mono 5 Years Ago. Am I Still Contagious?

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?

The virus that causes mono stays in the body for the rest of a person's life, and can be in his or her saliva from time to time. But that person is most contagious from right before their mono symptoms start until the symptoms go away. Over time, the virus becomes less contagious, and after 5 years, it is unlikely for you to give it to someone. Most doctors recommend that people avoid kissing for about 6 months after they feel better. And it’s always a good idea to avoid sharing utensils, cups, and toothbrushes.

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 about 4 to 7 weeks after infection for the symptoms of mono to show up — not 4 days!

Reviewed by: Larissa Hirsch, MD
Date reviewed: January 2010

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