What Are the Symptoms of Mono in Teens?

Your teenager has been complaining about being tired for weeks, despite your insistence that they don’t stay up late texting, watching TV or playing video games. Then one day, they come home with a sore throat and you notice swollen lymph nodes in their neck.

You mentally go down the list of things they could have: It could be the flu, but they aren’t stuffed up. It could be strep throat, but their mouth looks okay—no white or gray patches on the tongue or throat.

Next on the list is mono (or mononucleosis), a virus typically characterized by fatigue, sore throat, fever and swollen lymph nodes. Here, everything you need to know about mono, how to treat it and how to keep it from spreading.

What is Mono?

The term mono actually refers to a group of viruses, says Rebekah Diamond, MD, a pediatric hospitalist in New York City and Assistant Professor of Pediatrics at Columbia University. “It’s an old term that describes a group of viruses with similar symptoms and laboratory findings. When we talk about mono today, we typically are referring to an infection with a virus called Epstein-Barr Virus (EBV).”

Even though doctors know more about this virus today than they used to, EBV is not technically the only virus that causes this illness. “Other viruses like cytomegalovirus (CMV) and adenovirus can cause a similar presentation that might also get labeled as "mono,” explains Dr. Diamond. But regardless of the specific cause, symptoms and treatment will be the same.

How It Spreads

Mono is typically spread through saliva, which is why it earned its nickname “the kissing disease.” But kissing is not the only way teens can catch the virus. “The vast majority of infections are transmitted through saliva, which can be from kissing, but it can also be from sharing glasses or spoons and occasionally from sneezing or coughing very close to someone,” Dr. Diamond explains.

The virus has a long incubation period of four to six weeks, which means that kids are infected several weeks before they start to show symptoms. This is one of the reasons people think of mono as very contagious, though that’s not really the case.

“Mono is actually not as infectious as the common cold, for example, among other illnesses,” says Vivek Cherian MD, a Chicago-based internal medicine physician. However, Dr. Cherian adds that the virus can hang around in an infected teen for several months after infection, during which it can be spread to others.

Fortunately, because it is transmitted through saliva, it’s relatively easy for parents to limit the spread. Dr. Cherian recommends that teens with mono don’t share food, utensils or glasses at minimum until their fever has improved but the longer the better.

“Parents definitely shouldn't worry about limiting teen kissing or other social contact simply because of the risk of mono,” Dr. Diamond adds. “Focusing on promoting healthy living (vaccines to prevent other damaging diseases) and helping kids remember to report when they have symptoms (so they can stay home and/or be mindful of being contagious) is the way to go.”

Symptoms of Mono

When symptoms do appear, they can be tough for teens. “The classic presentation of mono is
fevers, sore throat, and swollen lymph nodes and/or tonsils. Throat pain and swelling can be significant so some kids have trouble drinking and eating,” says Dr. Diamond. “Many people also experience a lot of fatigue and this can be pretty long lasting. Headache and stomachache also occur.”

While these symptoms are the ones that kids with mono will feel and struggle with, there are other more invisible ones that are important to be aware of. “Mono can cause enlargement of your spleen (and sometimes splenic rupture which can be life threatening),” says Dr. Cherian. “It can also cause inflammation in your liver, and less commonly anemia, inflammation of your heart muscle, or low
platelet counts.”

Diagnosis and Treatment

If you visit your teen’s pediatrician with a suspicion of mono, a simple blood test can confirm the diagnosis. From there, since mono is a virus (and not a bacterial infection like strep throat that can be treated with antibiotics), treatment is supportive.

“This means doctors and parents help kids stay hydrated, provide fever control and pain relief, and let the body heal by itself,” Dr. Diamond says. And these types of treatments, which can include Tylenol or Motrin for fever and aches, may be required for a while.

“It can take weeks for kids to feel fully like themselves and having prolonged symptoms like fatigue and swollen glands is common,” says Dr. Diamond.

Due to the enlargement of the spleen, which is a necessary part of the infection progressing and the body fighting it, your teen may need to be careful for a few months. “Because of the possible complication of a ruptured spleen, sometimes doctors suggest holding off participating in sports (or other intense activities) to help minimize the risk of this occurring,” Dr. Cherian explains.

When to Go Back to the Doctor

After your child’s initial diagnosis, there are two situations in which you may want to give the pediatrician another call. “Any new symptoms are always something to tell them about, and any symptom that was getting better (like fever) but starts to come back should be looked into,” Dr. Diamond says.

If you’re unsure about anything, call your child’s pediatrician at any time—but don’t stress too much, says Dr. Diamond. “Mono is just like a serious cold virus,” she shares. “Most people will have EBV at some point in their lives, even if they don't have symptoms! It's so incredibly common and something to be aware of but nothing to lose sleep over.”