When Ashley came home with a headache and body aches and pains, she thought she had caught the flu. By the next morning, Ashley's temperature had soared to 103°F (39.4°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 are exposed to the virus at some time in childhood.

Not everyone who is exposed to EBV develops 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 it's no joke if you have it. 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 nicknamed the "kissing disease." If you've 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 contact with saliva (spit), such as by sharing a drink, a toothbrush, an eating utensil, or even lip gloss, lipstick, or lip balm with someone who is infected with EBV. Researchers believe that mono may be passed sexually as well.

Experts think people with mono are most from the time they first get infected and then for the first 18 months after getting mono. But, because EBV stays in the body for life, the virus can show up in a person's saliva from time to time, and there's a chance that person may be contagious during these times, even if he or she feels OK.

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.

How Do I Know if I Have It?

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

• fatigue
• fever
• sore throat with swollen tonsils that may have white patches
• loss of appetite
• swollen lymph nodes (commonly called glands, located in your neck, underarms, and groin)
• headaches
• sore muscles
• weakness
• 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. Some people who get infected with EBV might not have any symptoms.

Even if you have several of these symptoms, don't try to diagnose yourself. See a doctor if you have a fever, sore throat, and swollen glands, or if you are unusually tired for no apparent reason. The symptoms of mono also can be signs of other illnesses, like the flu or strep throat, and how doctors treat you will depend on what's wrong. The treatments might be very different: For example, strep throat requires antibiotics, but mono does not.

To diagnose what's going on, the doctor will do a physical exam (for example, looking at your throat or feeling your lymph glands or spleen to see if they're larger). The doctor will usually do a throat swab and possibly also do some blood tests.

Sometimes a person might have mono and strep throat at the same time, though that's rare.

How Can I Get Better?

There is no cure for mononucleosis. Mono needs to run its course naturally. Symptoms may last 2 to 4 weeks, and some people feel tired for several weeks longer (that's why it's important to take care of yourself and get lots of rest).

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, some 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. Stay home from school, sports, and other activities and rest up in bed.

For fever and aching muscles, try taking acetaminophen or ibuprofen. Don't take aspirin unless your doctor tells you to: Aspirin has been linked to a serious disease in kids and teens called Reye syndrome, which can lead to liver failure and death.

Even if you're not hungry, try to eat healthy foods and drink lots of water to prevent dehydration. If you have a sore throat, gargle saltwater, drink tea with honey, or suck on hard candy or ice pops. 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 and don't overdo it. 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 and activity for at least a month after the illness because the spleen (an organ in the body that sits under the left ribcage) is often enlarged temporarily while you're ill. An enlarged spleen can burst easily, causing internal bleeding and abdominal pain and requiring emergency surgery. Do not participate in vigorous activities, contact sports, cheerleading, weightlifting, or even wrestling with your little siblings or your friends until your doctor gives you the OK.

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: Elana Pearl Ben Joseph, MD
Date reviewed: February 2013