Infectious Mononucleosis: Fact vs Fiction

Infectious mononucleosis, mono, or the “kissing disease,” is an illness causing prolonged fever, sore throat, and swollen lymph nodes. Its original name was actually “glandular fever.” We eventually changed the name to infectious mononucleosis because of the type of white blood cell that increases during the illness.


The Epstein Barr virus (EBV) causes the majority of mono cases. Other viruses, like cytomegalovirus (CMV) and adenoviruses, may cause a mono-like illness. If something other than EBV causes the illness, it’s technically called mononucleosis syndrome, though. Mono is pretty common, too. 25-50% of kids in the US have had EBV by the time they are 4 years old. By adulthood, the EBV prevalence is 90-95%.


I’d like to do a little mono “myth busting.”


Myth #1: Mono is a teenager and young adult illness.


False. Most cases of infectious mononucleosis in children end up being subclinical. That just means it’s not bad enough for someone to go searching for the cause. As kids get older, the incidence of symptomatic mono increases. It makes sense, though. As kids get older, their immune system gets hardier. Which means, the response to illnesses, like mono, are bigger and more noticeable.


Myth #2: Mono is very contagious.


False. Infectious mononucelosis is spread through shared saliva, which is why it is also called the “kissing disease.” But, since mono is not a particularly contagious illness, even sharing saliva with someone who has active mono doesn’t mean you will definitely come down with a case of your own. Mono is, however, contagious for a really long time, and symptoms don’t always show up right away. It may take 2-4 weeks for your symptoms to show up after you’ve been exposed to the illness. Then, once you recover, you can shed the mono virus for decades. Yes. DECADES.


Myth #3: Mono is a really bad illness.


False. Sort of. Many cases of mono are relatively mild. For the most part, mono is a viral illness causing sore throat, fever, and fatigue for 5-10 days. For some people, though, they may have symptoms for weeks to months. Also, when it’s your kid who has a fever, sore throat, and stiff neck from all of the swollen lymph nodes for 5 days, it really doesn’t feel “relatively mild.” Just like every other illness, some people have a particularly rough time with mono. However, overall, infectious mononucleosis is a mild viral illness.


So, here are a few tips if you think your child may have mono:



I realize this may sound unusual. However, remember how I mentioned mono is characterized by prolonged fever? Until you reach the “prolonged” point, mono looks like every other viral pharyngitis. Even the rapid mono test we do at KidMed is more accurate when your child has had symptoms for at least 3 days.



Mono can cause a sore throat with white spots on the tonsils. You know what else causes a sore throat with white tonsils? Strep throat. This is why it’s important not to assume a diagnosis. If you assume it’s strep and it’s mono, then you wrongly treat a viral illness with an antibiotic. If you assume it’s mono and it’s strep, a bacterial illness goes untreated. Here is a super common scenario:

A parent brings her child to KidMed because he has a sore throat, fever, swollen glands, and white spots on his tonsils for 1 day. The strep test is negative, so we send out a culture. The culture comes back 2-3 days later, and says “not strep,” but the child still has all of his symptoms.

It would be very easy to understand why some may lean towards “treat presumptively” for strep. BUT, a better option is to come back to KidMed for mono testing. The mono test is a blood test. We run a rapid test in-house. We can also send out “mono titers,” which tell us if your child has active mono, has had mono in the past, or is completely mono naïve.



Symptomatic management is the mainstay of mono treatment. Acetaminophen and ibuprofen, plenty of fluids and nutrition, and much rest. Some people may need an extra boost to help with the sore throat or stiff neck from swollen lymph nodes. These kids may benefit from an oral steroid, but talk with your diagnosing provider to decide what is best for your child.


Be patient

Mono takes longer to get over than some other viruses. Try not to get discouraged if you don’t feel back to 100% in 3-5 days. This is particularly difficult for my teenage patients. When your baseline is “go, go, go” mono can be quite frustrating. However, your body needs to rest to heal. Athletes also need to take notice: mono can cause your spleen to enlarge. If an enlarged spleen is hit hard, say in a contact sport, it can burst. This is bad, bad news. So, a general rule of thumb is, no contact or strenuous sports involvement for 3-4 weeks after your mono symptoms start.


Hopefully you and your child never have to deal with a mono infection. However, if you do, just remember that the pediatric experts at KidMed are here to help out!




  1. Help me understand this…. my child, a teen, tested positive for mono, a “recent, past infection”, we were told. He never had a sore throat, we never had indication of a fever, but yet, EBV was prevalent in his bloodwork. He sustained damage to his autonomic nervous system as a result of the virus, according to the cardiologist. Also, pediatrician, not believing he was symptomatic of mono, gave a flu shot, “because we don’t want him getting the flu”. We’ve been in a roller coaster for 2 years now. How could his blood indicate EBV infection, but he not have the “typical” symptoms?


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