False Positive on Mono Test

Did you know that the blood test used to identify infectious mononucleosis can yield a false positive?  Well, that seems to be the case with my five-year-old.  The good news is that she bounced back from whatever virus she did have in roughly 10 days — a simple nasty cold virus, as it turns out.  The only real down side is that she will not have developed any anti-bodies against mono when she is eventually exposed to it, as apparently almost every human being is at some point.

In the interim when we thought our innocent little five-year-old had mono, I did some research about it, and this is what I learned:

  • Mono seems to be primarily linked with the Epstein-Barr virus and usually results during an initial exposure to the virus.
  • It typically occurs in teenagers ages 15-17, but can be caught at any age.
  • Most adults over the age of 25 are immune, due to previous exposure.
  • The virus is transmitted through saliva, which is why the term “kissing disease” was coined.
  • It can take weeks or months to recover.
  • The main symptoms include a very sore throat with swollen and blistered tonsils, swollen lymph nodes (particularly in the neck), fever, and extreme fatigue.
  • One of the nastier symptoms that can occur is a swollen spleen, which means that anyone with mono should not play contact sports and risk further injury to the spleen.
  • Not everyone develops these symptoms when exposed to the Epstein-Barr virus.
  • The incubation period for mono is roughly 4-7 weeks, which means that people can be contagious for a long time before developing symptoms.
  • There is no medicine that has been shown to be effective in curing mono.  Antibiotics can actually make it worse, sometimes resulting in an additional rash.
  • The best treatment seems to be drinking fluids, getting plenty of rest, gargling with salt-water for the sore throat, and taking an over-the-counter medicine for the fever and discomfort, per your doctor’s recommendation.

A monospot test can be administered using a finger-prick blood test in order to determine whether or not a patient has mono, but according to my own experience, this test is not 100% accurate.  Even given my encounter with the false positive reading though, I’d still want the benefit of the test the next time around.  I’d rather have an educated guess about what my kids may or may not have, and it may be useful in ruling out mono or preparing for a long recovery.


  1. I always test positive for mono and fifths disease- I think some people are just weird like that :p . I hope your little one is feeling better by now.

  2. My little boy tested positive for mono, but dosnt show any signs of mono. The only symptom is swollen lymp nodes, no fever or sore throat. If you have had mono once do you always test postive?

  3. To be honest, I have no idea. Fortunately, she bounced back very quickly from whatever it was. I have heard that young children can be exposed to it and sometimes develop more mild symptoms than teens or adults, and that in some cases younger kids bounce back from it more quickly. I’m sure his doctor would know more about the details than me though. I hope your little boy is feeling better soon.

  4. Our 3 year old son tested positive for mono 3 months ago. We took him in due to him being tired a lot and swollen nodes. He woke up fro his nap today, 3 months later and had the swollen nodes. Took him in and they pricked his finger and he tested positive for mono again. It somewhat worries me that the doctors were puzzled that he would have it again so soon. This time he only has the swollen nodes, no other symptoms. Any ideas? Should we be worried?

  5. Nate, I don’t have any medical knowledge about mono, but from reading the rest of the comments on this post, it sounds like several others have experienced the same thing.

  6. I’m 19, I have tested positive for Mono 4 time since 2008. I’ve seen a specialist last time I tested positive, and really got now answer from her. I was just tested once more due to lack of motivation and just wanting to lay in bed, and tested positive for my fourth time, My doctor doesn’t believe it however. My question is why do I continue to get symptoms and test positive for mono… 😦

  7. Yikes, I sure hope she doesn’t have any of those things! Fortunately, she was vaccinated for two of the items on the list, and she hasn’t shown any other symptoms since she got over whatever the virus was.

  8. My daughter just got a positive diagnoses for Mono yesterday but I’m not convinced that she does, in fact, have Mono. She has a fever that comes and goes, swollen lymph nodes. But she also has a horrible head congestion, a nasty cough, a lost of appetite and diaherra. I’m curious about the false-positive and wonder if this is the case with my 5 yr. daughter. Could it be something else??! How do I find out? and exactly how does a 5 yr. get MONO?…

  9. Rebekah, I was just as baffled as you. My daughter had the other cold symptoms too when she tested positive for mono. In her case, she bounced right back within a week and a half. I would speculate that children can be exposed to mono by sharing drinks back and forth, since the virus can be passed through saliva, but apparently mono is more common in teens. A few other comments on this post have speculated as to reasons why a false positive might show up.

  10. I am 27, and this is the third time I have been diagnosed with mono. I have read a lot of contradicting info about if you can get it more then once. I don’t think it is mono, and can’t believe I have it for the third time. A family friend, a doctor, told me the problem with mono is every time I am tested it will show up as positive since it stays in your system. That friend has passed away, and now I have a different doctor and he is unwilling to consider anything else because the test for mono returns positive… time for a new doctor.

  11. My little girl who is 3 1/2 has tested positive for mono 3 times now. 1st time what March 2010, second was Jan. 2011 and the third time was April 2011. My pediatrician had a Epstein Barr Virus panel done on her and as it turns out the bloodwork showed that she’s never had mono; so three times she got a false positive. Somewhat concerns me as to what she may have had, but overall she seems healthy.

  12. Unfortunately my wife as child had a mother with Munchausen-by-proxy syndrome. She used some type of contact medication when my wife was 11, and it created all the symptoms of Epstein Barr/Infectious Mono, and the mono-spot test was positive. What she actually had was “drug-induced hepatitis.” It’s definitely NOT what your child had, but the doctor blew it and sent her home to her abuser. It wasn’t until, of all things, the school nurse called in a doctor who said he wanted to isolate her in the hospital for a week to see what would happen. (That would have cured her). “Miraculously”, she got better right after that.

  13. My son was recently diagnosed with mono. He had nothing but severe G.I. symptoms and I was thinking he could possibly have giardia. The next day we found out he also tested positive for giardia. All along my suspicions have told me he does not have mono. Is there any way I can find out if his mono test was a false positive?

  14. I don’t know of any definitive source for determining false positive results, but from what I’ve read on these comments and from my own experience, it seems like it sure does happen from time to time. Perhaps ask the doctor about it.

    In any case, I hope your son is feeling better soon!

  15. Monospot testing in young children can often yield a false positive result. That test should always be accompanied by EBV titers; if the IgM (early antibody) is positive, then it’s mono. If any of the other antibodies (IgG) are positive, this indicates a prior infection or merely exposure. My 4yr old had a false positive monospot a few months ago with negative EBV titers; therefore not mono. Currently, she has had swollen glands, exudative tonsillitis and fatigue. This time, her monospot was negative but EBV IgM was positive; therefore that equals mono. A monospot can also stay positive for many months; so once someone is positive; it is pointless to retest for a period of time afterward. EBV testing is much more specific and reliable. One can build up antibodies to EBV, but it is possible to have mono more than once, contrary to popular belief.

  16. My 9 year old daughter was diagnosed just today with infectious mono along with strep. She started running a fever on a Friday, and since it’s that time of the year and she wasn’t complaining about much else, I just took a wait and see approach. She’s my youngest of three and I have seen some weird stuff with fevers out of them. heck, my son once was running around, eating, laughing with a 104 for days. But by Tuesday, when she was still cycling up and down and was periodically telling me her throat hurt, I ran her in to the doc suspecting strep. Strep test came back negative, not the flu, no stomach problems, no rashes and just slightly swollen lymph nodes. She actually started getting better by Thursday, and I thought we were out of the woods. Friday afternoon, her fever came back with a vengeance and she went downhill from there. She was so sick by this morning that we literally jumped out of bed, threw on clothes and took her in. Her monospot test was positive, and I will say, this is one obviously very sick girl. No kinda sorta feeling bad, but clearly barely conscious sick., And she has the classic fever, throat, glands but nothing else (no rash, no chest congestion, no stomach issues either way). With some of the symptoms I see reported here, I would have questioned a positive test. Our neighbors college aged son had it last year and he was in a very similar state as our daughter and they had to make 2 ER runs. I know mono can present mildly, but in our case and others I know, these are really sick people.

  17. Cat, I hope your daughter feels better soon. It sounds like we got off lucky in our case, but I know mono can keep you down for the count for quite some time. Best wishes for a speedy recovery!

  18. My 14 year old daughter just tested positive for mono and she has no symptoms at all! I am so frustrated because she feels great but has to sit from sports for a month. I am wondering if she was exposed at a younger age and we passed it off for a cold or the flu and now maybe she is in a reactivation period and that’s why she tested positive.

  19. my 15 year old son tested positive for mono after having allergic reaction to amoxacilin that i feel dosage 0f 875 mg was to much. i had his spleen checked and it is not enlarged. he has no symtoms is playing sports a bad idea even though hes not sick?

    • If one has mono, taking Amoxicillin and Ampicillin can “bring out” the mono rash. It is not likely an allergic reaction. Also, 875 mg twice a day is not likely too much for a 15 year old. The recommended dose for ear infections, sinus infections, etc is 90 mg per kg of body weight. Enlarged spleen or not, no contact sports for at least 4 weeks is the official recommendation. After being in practice for 11 years with primarily a pediatric population, I have seen more than my share of mono!

  20. Hi my 5 year old just started kindergarten.. he came home with a fever on a tuesday of 102.8 after school. I kept him home the rest of the week. He was having fever spikes of 104 I took him to the Dr. Friday afternoon and they said.. Well it’s viral.. mono or strep or maybe the flu.. (No tests) and gave him an antibiotic. (Just in case) so Friday morning his fever was 104.8. So I maintained motrin tylenol alternating and kept it down through the day.. It started to go up after eve so I took him to an urgent care.. big mistake.. again no tests.. no fluids.. no answer.. Hes 5 for goodness sake! Sunday we managed and then Monday morning it spiked to 105.6.. Scared me to death. Ran him to the er.. they almost sent us away with no tests and I said hes not drinking and Im worried about his kidneys bc of lack of fluid. They found protein in his urine and then did blood tests and he has mono.. took him to his reg dr again the next day they swabbed him he has strep too! So.. its been 10 days and after antibiotic shots he still has a fever and his eyes are still swelled. HELP.. Will this ever end?

    • Jessica, it’s the worst thing for a parent to have to watch a child be sick and struggle with health issues. I’m so sorry you’re going through this. In my case, my daughter bounced back quickly, but you’re absolutely doing the right thing to keep seeking medical care until you get some answers. It sounds like you’re doing a great job advocating on your son’s behalf. I hope he gets better soon!

  21. When the test comes back positive for mono, was the testing a monospot type test? If so, were epstein viral antibodies for IgM and IgG done as a followup especially if there is a question about the test being positive. We are going thru something similiar with our 20 month granddaughter. She has a similiar presentation 4 months ago. We are not sure what’s going on at this point.

    • Yes, it was a monospot test, but I don’t think any follow up testing was done on the blood work, since it was a simple finger prick test. She didn’t have any tests other than that. Fortunately, in our case, my daughter bounced back in about 10 days. I’ve had colds that lasted longer. That’s why we had the impression that the test was likely a false positive, since mono usually lasts much longer.

  22. Glad I found this article. I was tested the other day for mono and was positive. Although I feel like I could have mono, I really wasn’t convinced it was mono based on my symptoms. Specifically swollen hands and feet. Well today my 10 year old woke up and looked like someone slapped her on both cheeks. That’s the classic diagnostic symptom for Fifth Disease. And sure enough so is peripheral edema in an adult. My mother told me I had mono as a child which is supposed to provide immunity and may explain a false positive test result.

    • Chris, I hope your doctor and your daughter’s doctor are able to figure it out and provide you with some relief. It’s never fun to be sick, but even more worrisome when you aren’t sure of the cause or treatment. Good luck!

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