UT University Health Services


Mononucleosis (also called mono) is a viral infection that frequently affects young people. It is a common infection and often causes minimal symptoms, especially when children have it. However, in adolescents and young adults, it often causes more intense symptoms and missed school.


The virus that causes infectious mono is called EBV (Epstein-Barr virus). It is spread mainly through saliva, which is why it has the nickname "kissing disease." EBV is a common virus that stays dormant in the body, occasionally becoming active but causing no notable symptoms. When the virus is active, it can be spread to others. Therefore it is possible, though rare, to get mono from someone who is not obviously sick.


After the virus enters the body, it can take up to a month before symptoms begin. The first symptoms usually include fatigue, fever, headache, and muscle aches. Many people have extreme fatigue and sleep 12 to 16 hours a day before they have any other symptoms. After just a few days of fever and aches, the throat becomes sore and the lymph nodes (glands) in the neck get bigger.

Other common symptoms are loss of appetite, nausea, joint aches, rash, and a vague sense of fullness or abdominal pain.


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

A blood sample will be taken to test for mono. The first blood test might be negative, but a complete blood count can show that a mono infection might be developing. Your provider may ask you to return in a few days for another blood test. If you have mono, the second test may be positive.


There is no specific drug treatment for 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 for the fever and sore throat.

If your symptoms seem to be worsening rather than gradually improving after one or two weeks, tell your health care provider. You could develop strep throat, a sinus infection, or another secondary infection that needs to be treated with antibiotics.

Sometimes the mono infection causes the tonsils to swell so much that they nearly block the throat. Steroids may be prescribed to try to decrease the size of the tonsils.

The virus may inflame your liver, so it is important not to drink alcohol when you have mono. Alcohol could further injure your liver.

An enlarged spleen might rupture should it be hit or strained. A rupture of the spleen causes severe bleeding and is a medical emergency. For this reason, you should avoid heavy lifting and any kind of jarring activity or contact sport while recovering from mono. Your activities will need to be restricted until your spleen returns to a normal size. Otherwise, you will gradually be able to return to school, work, and sports.

Recovery Time

Symptoms may get worse for two or three weeks after they first appear. Usually the fever, sore throat, and extreme fatigue last about one to two weeks. It can take several weeks, and in some cases several months, for the body's immune system to overcome the virus. You may continue to be contagious for many months after you recover from the infection.

After you recover from mono, the Epstein-Barr virus stays dormant in the body. It may become active occasionally throughout your life without causing any symptoms. When the virus is active, it can be spread to others. That is why people who have had mono can be contagious even when they feel well.


The best way to prevent others from getting mono is for them to avoid contact with your saliva. They can do this, for example, by avoiding kissing you and by not sharing food or eating and drinking containers and utensils.

Developed by RelayHealth.
Published by RelayHealth.
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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