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:

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.

Mono and Sports

Doctors usually recommend that kids who get mono avoid sports for at least a month after symptoms are gone because the spleen is usually enlarged temporarily from the illness. An enlarged spleen can rupture easily — causing internal bleeding, fever, and abdominal pain — and require emergency surgery. Vigorous activities, contact sports, weightlifting, cheerleading, or even wrestling with siblings or friends should be avoided until your doctor gives the OK.


Most kids who get mono recover completely with no problem, but in rare cases, complications can occur. These can include problems with the liver or spleen, anemia, meningitis, trouble breathing, or inflammation of the heart.

Prevention and Treatment

There is no vaccine for the Epstein-Barr virus, but you can try to protect your kids from mono by making sure that they avoid close contact with other kids who have it. But sometimes people have the virus without any symptoms and can still pass it to others. So teach your kids to wash their hands often, and not to share drinks or eating utensils with others, even when they seem healthy.

The best treatment for mono is plenty of rest, especially early in the course of the illness when symptoms are the most severe. Acetaminophen or ibuprofen can help to relieve the fever and aching muscles. Remember, never give aspirin to a child who has a viral illness because this has been associated with the development of Reye syndrome, which may lead to liver failure and can be fatal.

In most cases, the symptoms of mono go away in a matter of weeks with plenty of rest and fluids. After If the symptoms seem to linger, or if you have any other questions, talk with your doctor.

Reviewed by: Elana Pearl Ben-Joseph, MD
Date reviewed: February 2013

Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.

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OrganizationCenters for Disease Control and Prevention (CDC) The CDC (the national public health institute of the United States) promotes health and quality of life by preventing and controlling disease, injury, and disability.
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