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What is infectious mononucleosis?

Infectious mononucleosis, more commonly known as "mono,” is a viral illness that can cause flu-like symptoms, fatigue, and swollen lymph glands. It is common in teenagers and young adults, especially college students. Infectious mononucleosis is very contagious and is easily spread through saliva. It is often difficult to prevent since many people with the illness have no symptoms. Once you or your child has had infectious mononucleosis, the virus remains inactive in the throat and blood cells for life.

Symptoms & Causes

What are the symptoms of infectious mononucleosis?

Symptoms of infectious mononucleosis can vary child to child. Common symptoms include:

  • Fever
  • Swollen lymph glands in the neck, armpits and groin
  • Extreme fatigue
  • Sore throat, which can make swallowing difficult
  • Swollen spleen or liver
  • Headache or body aches

The symptoms usually last for about two to four weeks, but some people continue to feel tired for weeks after that.

What causes infectious mononucleosis?

The most common cause of infectious mononucleosis is the Epstein-Barr virus (EBV), but other viruses, such as the cytomegalovirus, can also cause it. It's often spread through contact with infected saliva (such as kissing, sneezing, or sharing a glass). Adolescents and young adults who are exposed to the Epstein-Barr virus have a 50 percent chance of developing symptoms.

Diagnosis & Treatments

How is infectious mononucleosis diagnosed?

Infectious mononucleosis is usually diagnosed based on symptoms and a physical exam. In some cases, your child’s doctor may also order tests to confirm a diagnosis, including a white blood cell count, heterophile antibody test, or monospot test.

How is infectious mononucleosis treated?

There is no specific treatment for infectious mononucleosis and no vaccine to prevent it. Symptoms usually go away on their own within two to eight weeks. Your child’s doctor may suggest some ways to help your child feel better while he or she is recovering, including:

  • Getting plenty of rest
  • Drinking lots of fluids
  • Taking over-the-counter medications to treat symptoms, such as fever or headache
  • In some cases, corticosteroids, a type of steroid medication, can reduce swelling of the throat and tonsils

How we care for infectious mononucleosis

The pediatric specialists at the Division of Adolescent/Young Adult Medicine at Boston Children's Hospital provide comprehensive primary care to patients ages 10 to 23. We have vast experience diagnosing and caring for common illnesses like infectious mononucleosis.