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When Ashley came home with a headache and body aches and pains, she thought she had caught the flu. But by the next morning, Ashley's temperature had soared to 103° F (39° C) and her throat felt like she'd swallowed hot coals. Even worse, she was so tired she could hardly lift her head off the pillow. Ashley had never felt this bad with any cold or flu.

Ashley's mom took her to the doctor, where a physical examination and a blood test revealed that Ashley had mononucleosis.

What Is Mono?

Infectious mononucleosis (pronounced: mah-no-noo-klee-oh-sus), sometimes called "mono" or "the kissing disease," is an infection usually caused by the Epstein-Barr virus (EBV). EBV is very common, and many people have been exposed to the virus at some time in childhood.

Not everyone who is exposed to EBV develops the symptoms of mono, though. As with many viruses, it is possible to be exposed to and infected with EBV without becoming sick.

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. People who do show symptoms of having mono probably will not get sick or have symptoms again.

Although EBV is the most common cause of mono, other viruses, such as cytomegalovirus (pronounced: 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.

People often kid around about mono, but as Ashley discovered, it's no joke. A case of mono can keep you out of commission for weeks.

How Do People Get Mono?

One common way to "catch" mono is by kissing someone who has been infected, which is how the illness got its "kissing disease" nickname. If you have never been infected with EBV, kissing someone who is infected can put you at risk for getting the disease.

But what if you haven't kissed anyone? You can also get mononucleosis through other types of direct contact with saliva (spit) from someone infected with EBV, such as by sharing a straw, a toothbrush, or an eating utensil.

Some people who have the virus in their bodies never have any symptoms, but it is still possible for them to pass it to others. Experts believe that EBV can even spread from people who had the virus months before.

How Do I Know if I Have It?

Symptoms usually begin to appear 4 to 7 weeks after infection with the virus. Signs that you may have mono include:

  • constant fatigue
  • fever
  • sore throat
  • loss of appetite
  • swollen lymph nodes (commonly called glands, located in your neck, underarms, and groin)
  • headaches
  • sore muscles
  • larger-than-normal liver or spleen
  • skin rash
  • abdominal pain

People who have mono may have different combinations of these symptoms, and some may have symptoms so mild that they hardly notice them. Others may have no symptoms at all.

Even if you have several of these symptoms, don't try to diagnose yourself. Always consult your doctor if you have a fever, sore throat, and swollen glands or are unusually tired for no apparent reason.

Because the symptoms of mono are so general and can be signs of other illnesses, it's possible to mistake mononucleosis for the flu, strep throat, or other diseases. In fact, occasionally some people may have mono and strep throat at the same time.

When making a diagnosis, the doctor may want to take some blood tests to see if mono is causing the symptoms. But even if the blood tests indicate mono, there isn't much the doctor can do other than advise a person to drink lots of fluids and get plenty of rest.

How Can I Get Better?

There is no cure for mononucleosis. But the good news is that even if you do nothing, the illness will go away by itself, usually in 3 to 4 weeks. Because mono is caused by a virus, antibiotics such as penicillin won't help unless you have an additional infection like strep throat. In fact, certain antibiotics can even cause a rash if you take them while you have mono.

Although there's no magic pill for mono, you can do some things to feel better. The best treatment is to get plenty of rest, especially during the beginning stages of the illness when your symptoms are the worst. Put yourself to bed and pass on school, sports, and other activities.

For the fever and aching muscles, try taking acetaminophen or ibuprofen. Steer clear of aspirin unless your doctor tells you to take it: Aspirin has been linked to a serious disease in kids and teens called Reye syndrome, which can lead to liver failure and death.

If you have a sore throat, chew gum, drink tea with honey, or suck on hard candy or ice pops. Even if you're not hungry, try to eat a well-balanced diet and drink lots of water and juices to prevent dehydration. You can get some nutrition and soothe your throat with cold fruit smoothies or low-fat shakes.

When you start feeling better, take it slow. Although you can return to school once your fever disappears, you may still feel tired. Your body will tell you when it's time to rest — listen to it. By taking good care of yourself and resting as much as you need to, you will soon be back to normal, usually within a few weeks.

Doctors also recommend avoiding sports for at least a month after the illness because the spleen (an organ in the body that sits under the left rib cage) is often enlarged temporarily while you are ill. An enlarged spleen can rupture easily, causing internal bleeding and abdominal pain and requiring emergency surgery. Do not participate in contact sports, cheerleading, or even wrestling with your little siblings or your friends until your doctor gives you permission.

As you recover, make sure you don't share the virus with your friends and family. Chances are they will not get the disease from casual contact with you, but you can take a few steps to help them stay germ free. Wash your hands often, cover your nose and mouth when you sneeze or cough, and keep your drinks and eating utensils to yourself. This is one time when your friends and family will thank you for being selfish.

Reviewed by: Larissa Hirsch, MD
Date reviewed: January 2007
Originally reviewed by: Catherine L. Lamprecht, MD

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

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