Mononucleosis, or mono, is a viral infection that causes fever, sore throat, and swollen lymph glands, most often in the neck.
Mono is often spread by saliva and close contact. It is known as "the kissing disease." Mono occurs most often in people ages 15 to 17, but the infection may develop at any age.
Mono is caused by the Epstein-Barr virus (EBV). Rarely, it is caused by other viruses, such as cytomegalovirus (CMV).
Mono may begin slowly with fatigue, a general ill feeling, headache, and sore throat. The sore throat slowly gets worse. Your tonsils become swollen and develop a whitish-yellow covering. Often, the lymph nodes in the neck are swollen and painful.
A pink, measles-like rash can occur, and is more likely if you take the medicine ampicillin or amoxicillin for a throat infection. (Antibiotics are typically not given without a test that shows you have a strep infection.)
Common symptoms of mono include:
Less common symptoms are:
Your health care provider will examine you. They may find:
Blood tests will be done, including:
The goal of treatment is to relieve symptoms. Steroid medicine (prednisone) may be given if your symptoms are severe.
Antiviral drugs, such as acyclovir, have little or no benefit.
To relieve typical symptoms:
Also avoid contact sports if your spleen is swollen (to prevent it from rupturing).
The fever usually drops in 10 days, and swollen lymph glands and spleen heal in 4 weeks. Tiredness usually goes away within a few weeks, but it may linger for 2 to 3 months.
Complications of mononucleosis may include:
Death is possible in people who have a weakened immune system.
The early symptoms of mono feel very much like any other illness caused by a virus. You do not need to contact a provider unless your symptoms last longer than 10 days or you develop:
Call 911 or go to an emergency room if you develop:
People with mono may be contagious while they have symptoms and for up to a few months afterwards. How long someone with the disease is contagious varies. The virus can live for several hours outside the body. Avoid kissing or sharing utensils if you or someone close to you has mono.
Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.