8 Signs You Could Have Mono–and You’re Not Just Super Tired

Mono, short for mononucleosis, is a common viral illness–and unwelcome rite of passage–for many adolescents and young adults. College students are particularly vulnerable, but infants and young children can get it too (although their mono symptoms are usually mild, if they have symptoms at all).

Classic signs of mono include fever, sore throat, swollen lymph nodes, and fatigue. Doctors often diagnose this infection based on a patient’s symptoms and physical exam results, although sometimes mono blood testing is ordered to confirm the diagnosis or rule out other causes.

Serious complications can occur, but most people recover with plenty of rest, fluids, gargling, and over-the-counter pain relievers. (Mono treatment is pretty much what your mom would recommend!)

Is mono contagious? Let’s put it this way: Mono is called “the kissing disease”–and not because there’s anything romantic about it! The Epstein-Barr virus (EBV), the most common cause of mono, hitches a ride in people’s saliva.

“You can pass it on when you have direct sharing of secretions, like kissing or sharing a cup,” says Christine Hermos, MD, assistant professor at the University of Massachusetts Medical School and pediatric infectious disease specialist at the UMass Memorial Children’s Medical Center.

Luckily, mono is less contagious than the common cold. People with mono don’t usually have coughing or sneezing, so they’re not spraying virus-containing droplets of saliva into the air, Dr. Hermos explains.

Mono can also be spread through blood and semen, but that occurs less frequently, according to the U.S. Centers for Disease Control and Prevention (CDC).

If you do come in contact with mono, it can take four to six weeks after you’ve been infected for mono symptoms to even appear. Many people start to feel better two to four weeks after that, but fatigue can persist for many weeks or even months.

So, how long are you contagious with mono? Studies have not established a firm timeline. It may depend on your symptoms, so patients should talk to their doctors. “I usually tell them they’re probably shedding virus for about three weeks until their fever resolves,” Dr. Hermos says.

At least it’s uncommon to get mono more than once. After you’ve had mono, the Epstein-Barr virus hides in your body but rarely causes symptoms a second time. Roughly 90% of adults have antibodies against Epstein-Barr in their blood, meaning they’ve been exposed to the virus years earlier, probably in childhood.

Think you might be tangling with a case of mono? Here’s a symptom-by-symptom checklist of what to look for.

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Lymph nodes play a role in cancer diagnoses, as well as trapping bacteria and viruses.