What is infectious mononucleosis in teens and young adults?

Infectious mononucleosis is a contagious illness. It’s common in teens and young adults. It is also known as mononucleosis, mono, glandular fever, or the “kissing disease.”

What causes mono in a teen or young adult?

Mono is often caused by the Epstein-Barr virus (EBV). It may also be caused by cytomegalovirus (CMV). Both viruses are members of the herpes simplex virus family.

Mono is most often spread by contact with infected spit (saliva). But it can also be spread through blood or other body fluids. It's hard to keep it from spreading because even people with no symptoms can carry the virus in their saliva and infect other people.

What are the symptoms of mono in a teen or young adult?

Most healthy people who get the CMV virus have few or no symptoms. Some may develop symptoms. Mono caused by EBV causes symptoms more often.

Symptoms of mono can take between 4 to 6 weeks to appear. They can last for weeks or months. They usually don’t last beyond 4 months.

The most common symptoms of mono include:

• Fever

• Headache

• Extreme tiredness (fatigue)

• Swollen lymph glands in the neck, armpits, and groin

• Headaches and body aches

• Sore throat because of enlarged tonsils (tonsillitis). This can make it hard to swallow.

• Enlarged spleen

• Mild liver damage that can cause short-term yellowing of the skin and eyes (jaundice)

• Rash

Once a child gets mono, the virus stays inactive in the body for life. Only rarely can it become active again. 

The symptoms of mono can be like other health conditions. Have your child see their healthcare provider for a diagnosis.

How is mono diagnosed in a teen or young adult?

The healthcare provider will ask about your child’s symptoms and health history. The provider will give your child a physical exam. The symptoms may be enough to diagnose mono. The diagnosis may be confirmed with blood tests for:

• White blood cell count

• Antibodies to the virus

• Direct tests for the virus itself

• Liver function

How is mono treated in a teen or young adult?

Treatment will depend on your child’s symptoms, age, and general health. It will also depend on how bad the condition is.

Prescription medicines are rarely needed in the treatment of mono. In most cases of mono, care to ease symptoms is all that is needed.

To ease symptoms, help your child:

• Get lots of rest

• Drink plenty of fluids to stay hydrated

• Take over-the-counter medicine for fever and discomfort

Antibiotics will not help your child's mono get better.

In more severe cases, swelling of the throat and tonsils may make breathing hard. If breathing becomes difficult, your child should be seen right away in an emergency department. Your child will often be seen by an ear, nose, and throat healthcare provider (otolaryngologist). Corticosteroids will often be used to reduce the swelling.

Corticosteroids may also be prescribed if the fever and fatigue are severe or last a long time, to reduce inflammation and ease the symptoms.

What are possible complications of mono in a teen or young adult?

The spleen may become enlarged because of the virus. An enlarged spleen is at risk of rupture if your child is injured or in an accident, or if major pressure is put on the stomach area. To protect the spleen, your child should not play any contact sports until fully recovered.

As discussed above, swelling of the throat or tonsils can cause difficulty breathing.

Some people will suffer from prolonged or severe fevers and fatigue that can make it difficult to return to normal activities for many weeks or months.

Both EBV and CMV stay in a person's cells for life, even after the symptoms of the virus are gone. The virus can become active again, but it usually doesn't cause symptoms.

When should I call my teen’s or young adult’s healthcare provider?

Call the healthcare provider if your teen or young adult has:

• Symptoms that don’t get better, or get worse

• New symptoms

Key points about mono in teens and young adults

• Infectious mononucleosis (mono) is often caused by the Epstein-Barr virus (EBV). It may also be caused by cytomegalovirus (CMV). 

• Mono is most often spread by contact with infected spit (saliva).

• Symptoms of mono can take between 4 to 6 weeks to appear. They can last for weeks or months. The most common symptoms of mono include fever, headache, extreme tiredness, swollen lymph glands, and sore throat.

• The spleen may enlarge because of the virus. It’s then at risk of rupture if your child is injured or in an accident.

• Corticosteroids may be prescribed for certain complications of mono.

• Both EBV and CMV stay in a person's cells for life, even after the symptoms of the virus are gone. The virus can become active again, but it usually doesn't cause symptoms.

Next steps

Tips to help you get the most from a visit to your child’s healthcare provider:

• Know the reason for the visit and what you want to happen.

• Before your visit, write down questions you want answered.

• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you for your child.

• Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.

• Ask if your child’s condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if your child does not take the medicine or have the test or procedure.

• If your child has a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your child’s healthcare provider after office hours. This is important if your child becomes ill and you have questions or need advice.