What Increases Your Risk

Mono is usually caused by the Epstein-Barr virus (EBV). You are at increased risk of getting mono if you:

• Are age 15 to 24, especially if you are in close contact with many people.¹ In the United States, college students, nurses, and people in the military are most likely to get mono.
• Have intimate contact with a person who has mono or an active EBV infection. (A brief kiss on the lips is not likely to spread EBV. It is spread when saliva from an infected person gets into another person's mouth.)
• Share drinking glasses, eating utensils, dishes, or a toothbrush with an infected person. A person does not have to have symptoms of mono to spread EBV.

After you have been infected with EBV, the virus may stay in your body for the rest of your life. But you will not get mono again.

EBV is not spread through the air. You can live with a person who has mono and never become infected with the virus.

Most people have been infected with EBV before, so they usually don't get mono when they are exposed to a person who has it.

When To Call a Doctor

If you have been diagnosed with mono, seek care immediately if:

• You have severe pain in the upper left part of your abdomen. This may mean that your spleen has ruptured. Rupture of an enlarged spleen caused by mono is rare. It is most likely to happen because of a blow to the abdomen.⁴
• Your tonsils become so swollen that you find it difficult to breathe or swallow.

If you have not been diagnosed with mono and you have a severe sore throat that has lasted longer than 2 to 3 days after trying home treatment, call your doctor in 1 to 2 days.

If you have not been diagnosed with mono and have tried home treatment for 7 to 10 days, contact your doctor if you have:

• A lack of energy.
• Body aches.
• Swollen lymph nodes (sometimes called swollen glands).

Watchful waiting

Most cases of mono do not require treatment, but you still need to take care of yourself until the illness goes away. You should see your doctor to make sure your symptoms are not caused by a treatable infection, such as strep throat. If it is certain you have mono:

• Get plenty of rest.
• Gargle with salt water or use throat lozenges to soothe your throat.
• Take nonprescription pain relievers to reduce fever and relieve a sore throat and headaches.
• Avoid contact sports and heavy lifting for 4 weeks after you become ill with mono (or until a doctor tells you it is okay). Mono can cause your spleen to enlarge, and these activities can increase your risk for injuring your spleen.

Who to see

The following health professionals can diagnose and treat mono:

• Family medicine doctor
• Pediatrician
• Internist
• Physician assistant
• Nurse practitioner

To prepare for your appointment, see the topic Making the Most of Your Appointment.