Infectious Mononucleosis

It (also called mono) is a viral infection. It is a common infection, but often it causes no symptoms, especially when younger children have it. However, for adolescents and young adults it is a frequent cause of illness and missed school.

How does it occur?

The virus that causes infectious mono is called the Epstein-Barr virus (EBV). It is spread mainly through saliva, which is why it has the nickname "kissing disease."

What are the symptoms?

After the virus enters the body it can take up to a month before symptoms begin. The first symptoms usually are:

Many people have extreme tiredness before they have any other symptoms. They may find that they are sleeping 12 to 16 hours a day.

After a few days of fever and aches, other symptoms are:

You may also have:

How is it diagnosed?

Your healthcare provider will ask about your symptoms and examine you. Your provider will look for fever; a red throat with enlarged tonsils, sometimes covered with pus; and enlarged lymph nodes in the neck. You may also have a red rash, especially on the chest, and an enlarged spleen (in the upper left abdomen).

A blood sample will be taken to test for infectious mono. The first blood test might be negative. If your provider thinks you have mono, you may be asked to return in a few days for another blood test. If you have mono, this second test is usually positive.

You may also have a throat swab to check for strep throat.

How is it treated?

There is no specific drug treatment for infectious mono. Because it is a viral illness, antibiotics are not helpful. The most important thing you can do is to get plenty of rest. Take acetaminophen or ibuprofen for fever and sore throat.

If your symptoms seem to be worsening rather than getting better after a couple of weeks, tell your healthcare provider. You could develop strep throat or a sinus infection.

An uncommon complication of infectious mono is an abscess (pocket of infection) on one or both tonsils. These infections need to be treated with antibiotics.

Sometimes the mono infection causes the tonsils to become so big that they nearly block the throat. Your healthcare provider might prescribe steroids (Prednisone) to try to decrease the size of the tonsils.

The virus might inflame your liver. Do not drink alcohol when you have mono because alcohol could further hurt your liver.

You should avoid heavy lifting and any kind of jarring activity or contact sport for about 1 month. If your spleen is enlarged from the mono, it could rupture if it is hit or strained. A rupture of the spleen causes severe bleeding and is a medical emergency.

Check with your healthcare provider about how long you should avoid these activities. Otherwise, you will gradually be able to return to school, work, and sports.

How long will the effects last?

Usually the fever, sore throat, and extreme fatigue last about 1 to 2 weeks. The illness is most contagious during this time.

It can take several weeks, and in some cases several months, for the body's immune system to overcome the virus, but the illness is less contagious after the fever has been gone a few days.

The Epstein-Barr virus stays in the body even after you recover. You could have mono again, but this does not usually happen.

How can I take care of myself?

How can I help prevent mononucleosis?

The best way to prevent others around you from getting mono is for them to avoid contact with your saliva. They should avoid kissing you and not share food, eating utensils, or drink containers until it has been several days since you stopped having a fever. The virus becomes less contagious at this time.

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This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.

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