Mononucleosis

What Is "Mono"?

Kids and teens with mononucleosis (mono) develop flu-like symptoms that usually go away on their own after a few weeks of rest and plenty of fluids.

Mono usually is caused by the Epstein-Barr virus (EBV), a very common virus that most kids are exposed to at some point while growing up. Infants and young kids infected with EBV usually have very mild symptoms or none at all. But teens and young adults who become infected often develop mono.

Mono is spread through kissing, coughing, sneezing, or any contact with the saliva of someone who has been infected with the virus. (That's how mono got nicknamed "the kissing disease.") It also can spread spread by sharing a straw or an eating utensil. Researchers believe that mono may be spread sexually as well.

People who have been infected with EBV will carry the virus for the rest of their lives — even if they never have any signs or symptoms of mono. Those who did have mono symptoms probably will not get sick or have symptoms again.

Although EBV is the most common cause of mono, other viruses, such as cytomegalovirus (sye-toe-meh-guh-low-VYE-rus), can cause a similar illness. Like EBV, cytomegalovirus stays in the body for life and may not cause any symptoms.

Signs & Symptoms

Symptoms of mono — such as fever, a sore throat, swollen lymph nodes (in the neck, underarms, or groin), or unexplained fatigue or weakness — can be mistaken for the flu or strep throat.

Other symptoms of mono include:

• headaches
• sore muscles
• swollen tonsils
• skin rash
• abdominal pain

Kids with mono may have different combinations of these symptoms, while some teens might have symptoms so mild that they're hardly noticeable. Mono symptoms usually go away on their own within 2 to 4 weeks. In some teens, though, the fatigue and weakness can last for months.

To make a diagnosis, the doctor may perform a blood test and physical exam to check for things like swollen tonsils and an enlarged liver or spleen, which often is a sign of the infection.