person holding mug

—Camden*, Saint Louis, Missouri

I get this question fairly often. Here’s what’s important to know: Most students know someone who has been diagnosed with mono (infectious mononucleosis) in the past year and a half, and virtually all students have people in their close circles who’ve recently had mono, though neither party may be aware of it (some people have mild or uncharacteristic cases of mono and may not get diagnosed). The question, then, is not “Might I have mono?” but rather “Would it matter if I had mono?”

Someone with no symptoms who’s at no risk of complications might not need to know if they have or have had mono. Why? Because there’s no specific vaccine, cure, or treatment for mono; just ways to make symptoms (e.g., sore throat) more bearable. If you don’t have symptoms, there isn’t anything to treat and just knowing someone with mono isn’t really grounds for getting tested.

If, however, you have a terrible sore throat or fatigue, or if, for some other reason, you’re having trouble performing at your usual cognitive or physical levels, you should consider making an appointment with your health care provider.

But since you asked, let’s dig in a little deeper to get the backstory on mono.

What exactly is “mono”?

Infectious mononucleosis—or mono, for short—can be caused by any of several viruses, but most commonly it’s caused by Epstein-Barr virus (EBV). Mono is transmitted via saliva, hence why it’s commonly referred to as the “kissing disease.”

People are most contagious when they’re most symptomatic, but may remain contagious for up to 18 months. Because of its long-lasting infectiousness and how easy it is to spread, mono is a pretty common problem for students.

Interestingly, people who are infected with EBV at a younger age (e.g., in elementary school) may get less sick from it. We sometimes find that people have antibodies to EBV without known past history of mono; they had an infection that, for whatever reason, didn’t get recognized or diagnosed. Prior infection with EBV is fairly protective; in most cases, you can only get mono once (though that’s not exclusively the case, so don’t bank on it). 

What are the symptoms of mono?

sick girl in bed vectorNewly onset mono most often looks like this:

  • Swollen, inflamed tonsils coated in fluffy, white patches of white blood cells (called exudative tonsillitis)
  • Swollen lymph nodes, especially in the back of the neck
  • Fever
  • Nausea
  • A horrendous sore throat that usually lasts 5–10 days (and is treatable with various medication strategies)

After the sore throat phase, the patient usually experiences about two weeks of very intense fatigue. You might find it’s hard to do much more than eat and get to school. After that, it’s two to four more weeks of less-than-usual energy levels and easy fatigue. For some people, one or more of these phases may be more or less intense, longer, or shorter. Some people only feel bad for a few days. Rarely, some are so miserable and exhausted they need to take a medical leave from school or work. Occasionally, people ask their health care provider to test for mono only because they’ve been experiencing intense fatigue or other less classic symptoms.

How do I know if I have it?

If you suspect that you might have mono, go to your school nurse or make an appointment with your health care provider. If, based on your symptoms and physical exam findings, your provider suspects mono, this will be confirmed with one of several tests. Many clinics have a rapid mono test that gives results in about 10 minutes. Sometimes a blood count may be ordered.

In certain circumstances, the doctor may order EBV serology, which is testing for antibodies to EBV, the profile of which helps us understand how recently the person was infected.

What are the complications?

what are the symptoms of monoFatigue and sore throat

The most common complications of mono are the effects on the ability to keep up with academics and participate in sports. Pain from the sore throat and potentially intrusive fatigue can make attending class and getting schoolwork done a challenge. People with mono should avoid vigorous exercise for the first 30 days of illness. Spending energy on exercise can delay or prolong recovery.

Rupture of the spleen

A more worrisome—but very rare—complication of mono is injury to or rupture of the spleen that’s enlarged and inflamed.

Liver inflammation

Some people with mono can develop inflammation of the liver.

*Name changed