Is it OK to have sex with my girlfriend if she has mono?

Q: My girlfriend currently has mono and I have already had it. Is it OK if we have sex? What are any risks associated with having sex with her while she has mono?

A: Great question. Seems simple, but really lots of layers.

“Mono” (infectious mononucleosis) technically refers to a syndrome of symptoms – swollen lymph nodes, fever, sore throat, fatigue, etc. – rather than a specific infection.  Most cases of mono in the US are thought to be caused by the Epstein-Barr virus (EBV) but other viruses, such as Cytomegalovirus, can cause mono as well.  But let’s assume that we’re talking about the usual EBV version of mono.

If your girlfriend has typical symptoms and a blood test that confirmed the diagnosis, then she is almost certainly infectious.  EBV concentrates in saliva, so people usually catch it through a cough, sharing utensils, or most famously, kissing.  EBV can be transmitted in other ways.  Although not technically considered a sexually transmitted infection, one published study suggests that EBV can be transmitted through sexual intercourse and that condoms offer some protection.   

Most (not all) healthy people who have had EBV mono develop immunity to it and do not get sick from subsequent exposures, so there is little risk of you getting mono again if you guys have sex.  You will almost assuredly be exposed to your girlfriend’s EBV – so there is a significant risk that you will be re-infected, but miniscule risk that you will develop mono again.

But let’s think about your girlfriend for a second.  Assuming she actually feels up to having sex, is it safe for her?

It’s unlikely that having sex would pose any particular risks.  Mono will sometimes cause a person’s spleen to become enlarged, however, which places them at risk of having a spleen rupture, a true surgical emergency.  In fact, we often tell people with mono to avoid contact sports and certain other physical activities for several weeks to make sure the spleen has had time to return to normal size.  So theoretically, depending on the vigorousness of the sex, there might be a risk of injury to your girlfriend’s spleen.

The severity of EBV mono can range from unnoticeable to severe (sometimes requiring hospitalization), with most people falling somewhere in the middle.  I have no idea where along this spectrum your girlfriend falls, but if she was feeling lousy enough to end up in the doctor’s office, maybe sex isn’t really a priority for her at the moment?  Why don’t you pick up some popsicles for her or offer to take her dog for a walk and reassess the sex thing in a day or two… or ten.

James R. Jacobs, M.D., Ph.D.
Student Health Services
The Ohio State University

19 thoughts on “Is it OK to have sex with my girlfriend if she has mono?

    • If your girlfriend has fully recovered and she feels well enough, and her doctor has not said otherwise, it should be OK. Let your girlfriend be the deciding factor in this one. She’ll know when she’s ready.

  1. i think having sex with your girlfriend is immoral.
    i can not accept this .
    but if you want to marry her it would be something else.
    it takes a lot of time to discuss.

  2. I had mono a year ago and it became reactive. I have no symptoms of it and I feel fine and normal. But sense it is reactive, if I kiss somebody or do anything with them will they get it?

    • Recurrent mono is extremely rare. There are multiple “mono-like” illnesses that may cause the same symptoms as mono. Mono is not a highly contagious illness, and if the diagnosis of mono was made one year ago and documented by laboratory testing, it would be highly unlikely that the patient in question is contagious.

  3. I caught mono flats Friday and i don’t have symptoms now , is it okay to have sex with my girl ?

  4. I have a question, please someone answer…. i was diagnosed with mono around two weeks ago. I was sick for about a month. Now i feel better, but how long until i can kiss my boyfriend again ?

  5. i think it’s better to wait for illness to cure first, sex not important priority

  6. Can I get mono by eating out my girlfriend? I have mono but she doesn’t, will eating her out infect her?

  7. I was diagnosed with mono a month ago. My boyfriend has never had mono. I have no swollen organs. Would it be safe to have sex/ oral sex with each other if no mouth to mouth kissing is involved? By safe I mean could he become infected with the EBV virus that could potentially lead to mono if his urethra is exposed to my vaginal/ oral fluids or if his mouth is exposed to my vaginal fluids? How long do I have to wait until I can kiss him without infecting him? Are there any lab tests to determine when it is safe to kiss him without infecting him? Are there any lab tests to determine if he has been exposed to the EBV virus before? If he has been exposed before, could he still develop mono if he is reinfected?

  8. My 46 year old girlfriend had mono at a young age. She gets intermittent periods of sores in her mouth. Recently (2 weeks ago) she had flu-like symptoms. She seems to be gettng better, fever free for almost a week.The doctor says she may have another bout of EBV. She seemingly is on the mend.
    a-is she at risk flying?
    b-am I at risk performing oral sex with her and or intercourse?

  9. Q: when I was 15 I had mono from sharing a Gatorade with a friend that had mono and didn’t know it.. Now that I’m 26 and had my son at 19 and mono stays in the body for life . Does that mean my child has it ? Sense he was in my body?

  10. I got my test back the other day saying I have mono, my boyfriend ive been with for a few months had lately not feeling the best and thinks he has it which he is getting tested. If he ends up having it is it okay that we still kiss and have sex ?

  11. I wants to know that when i kiss a guy he is facing soar throat problem all the time but at the same time i am not facing any symptoms of Mononucleosis . Am i suffering from Mononucleosis???

  12. so my bf has never had mono before and he went to the doctor and apparently he has mono and strep. I have never had mono before so is there any way strep can trugger mono? how does two people get mono if they both have never had it before?

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