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What Is Mononucleosis?

Mononucleosis (mono) is a group of symptoms usually caused by a virus. In kids and teens it can cause flu-like symptoms such as:

  • a fever
  • muscle aches
  • tiredness
  • a sore throat

These go away on their own after a few weeks of rest and plenty of fluids.

What Causes Mononucleosis?

Mononucleosis (mah-no-noo-klee-OH-sus) usually is caused by the Epstein-Barr virus (EBV). Most kids are exposed to this common virus at some point while growing up. Infants and young kids infected with EBV typically have very mild symptoms or none at all. But infected teens and young adults often develop mono.

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 (sy-toe-meh-guh-low-VY-rus), can cause a similar illness. Like EBV, cytomegalovirus stays in the body for life and may not cause any symptoms.

How Does Mono Spread?

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

What Are the Signs & Symptoms of Mononucleosis?

Symptoms usually show up about 4 to 7 weeks after infection with the virus and can include:

  • being very tired
  • fever
  • sore throat with swollen tonsils that may have white patches
  • loss of appetite
  • swollen lymph nodes (or glands) in the neck, underarms, and groin
  • headaches
  • sore muscles
  • weakness
  • larger-than-normal liver or spleen
  • skin rash
  • belly pain

Mono symptoms usually go away within 2 to 4 weeks. In some teens, though, the tiredness and weakness can last for months.

How Is Mono Diagnosed?

To diagnose mono, the doctor may do 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.

How Is Mono Treated?

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

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

When Can Kids With Mono Play Sports?

Doctors recommend that kids who get mono avoid sports for at least a month after symptoms are gone. That's because the spleen usually is enlarged temporarily from the illness. An enlarged spleen can rupture easily, causing internal bleeding and belly pain, and need emergency surgery.

So vigorous activities, contact sports, weightlifting, cheerleading, or even wrestling with siblings or friends should be avoided until the doctor says it's OK.

What Problems Can Happen?

Most kids who get mono recover completely with no problems. In rare cases, though, complications can include problems with the liver or spleen, anemia, meningitis, trouble breathing, or heart inflammation.

Can Mono Be Prevented?

There is no vaccine to protect again the Epstein-Barr virus. But you can help protect your kids from mono by making sure that they avoid close contact with anyone who has it.

Many people who have mono won't have symptoms, but they can still pass it to others. So kids should wash their hands well and often, and not share drinks or eating utensils with others, even people who seem healthy.

Reviewed by: Elana Pearl Ben-Joseph, MD
Date Reviewed: 01-10-2016

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