Infectious Mononucleosis Learning Center

  • Enlarge
  • Print
  • Recommend

Infectious Mononucleosis

What is infectious mononucleosis (mono)?

Infectious mononucleosis, or mono, refers to a group of symptoms usually caused by the Epstein-Barr virus (EBV). It typically occurs in teenagers, but you can get it at any age. The virus is spread through saliva, which is why some people call it “the kissing disease.”

People with mono often have a high fever, swollen lymph glands, and a sore throat. Most cases of mono are mild and resolve easily with minimal treatment. The infection is typically not serious and usually goes away on its own in one to two months.

What are the symptoms of mono?

The incubation period of the virus is the time between when you contract the infection and when you start to have symptoms. It lasts four to six weeks. The signs and symptoms of mono typically last for one to two months.

The symptoms may include:

  • a fever
  • a sore throat
  • swollen lymph glands in the neck and armpits
  • a headache
  • fatigue
  • muscle weakness
  • swollen tonsils
  • night sweats

Occasionally, your spleen or liver may also swell, but mononucleosis is rarely ever fatal. 

Mono is hard to distinguish from other common viruses such as the flu. If your symptoms don’t improve after one or two weeks of home treatment such as resting, getting enough fluids, and eating healthy foods, see your doctor.

What causes mono?

Mononucleosis is caused by the EBV. According to the Centers for Disease Control and Prevention (CDC), EBV is a member of the herpes virus family and is one of the most common viruses to infect humans around the world.

The virus is spread through direct contact with saliva from the mouth of an infected person and cannot be spread through blood contact. You can be exposed to the virus by a cough or sneeze, by kissing, or by sharing food or drinks with someone who has mono. It usually takes four to eight weeks for symptoms to develop after you’re infected.

In adolescents and adults, the infection causes noticeable symptoms in 35 to 50 percent of cases. In children, the virus typically causes no symptoms and the infection often goes unrecognized.

Who is at risk for mono?

The following groups have a higher risk for getting mono:

  • young people between the ages of 15 and 30
  • students
  • medical interns
  • nurses
  • caregivers
  • people who take medications that suppress the immune system

Anyone who regularly comes into close contact with large numbers of people is at an increased risk for mono. This is why high school and college students frequently become infected.

How is mono diagnosed?

Your doctor can usually diagnose mono based on the presence of symptoms such as a fever, a sore throat, and swollen lymph glands. Your age is also a good indicator. Mono usually occurs in teenagers, but it can occur in people at any age.

Blood tests may be used to confirm the diagnosis.

White blood cell count

A mono infection typically causes your body to produce more white blood cells as it tries to defend itself. A high white blood cell count cannot confirm an infection with EBV, but the result suggests that it’s a strong possibility.

EBV antibodies (mono spot test)

A positive mono spot test is usually enough to confirm infectious mononucleosis. The mono spot test is a rapid test used to detect the presence of antibodies to EBV. Antibodies are proteins that your immune system releases naturally in response to a harmful substance called an antigen.

Specifically, the mono spot test is used to detect antibodies to EBV antigens. You may not have a detectable level of antibodies early in the illness. If this occurs, the test may need to be repeated in 10 to 14 days.

How is mono treated?

There’s no specific treatment for infectious mononucleosis. However, your doctor may prescribe a corticosteroid medication to reduce throat and tonsil swelling. The symptoms usually resolve on their own in one to two months.

Treatment is aimed at easing your symptoms. This includes using over-the-counter (OTC) medicines to reduce fever and techniques to calm a sore throat, such as gargling salt water. Other home treatments that may ease symptoms include:

  • getting a lot of rest
  • staying hydrated, ideally by drinking water
  • eating warm chicken soup
  • using OTC pain medications such as Tylenol

Contact your doctor if your symptoms get worse or if you have intense abdominal pain.

What are the possible complications of mono?

Mono is typically not serious. In some cases, people who have mono get secondary infections such as strep throat, sinus infections, or tonsillitis. In rare cases, some people may develop the following complications:

Enlarged spleen

You should wait at least one month before doing any vigorous activities or playing contact sports to avoid rupturing your spleen, which may be swollen from the infection. Talk to your doctor about when you can return to your normal activities. A ruptured spleen in people who have mono is rare, but it is a life-threatening emergency. Call your doctor immediately if you have mono and experience a sharp, sudden pain in the upper left part of your abdomen.

Inflammation of the liver

Hepatitis (liver inflammation) or jaundice (yellowing of the skin and eyes) may occasionally occur in people who have mono.

Rare complications

According to the Mayo Clinic, mono can also cause some of these extremely rare complications:

  • anemia, which is a decrease in your red blood cell count
  • thrombocytopenia, which is a decrease in platelets, the part of your blood that begins the clotting process
  • inflammation of the heart
  • complications that involve the nervous system, such as meningitis or Guillain-Barre syndrome
  • swollen tonsils that can obstruct breathing

Outlook and recovery from mono

The symptoms of mono seldom last for more than four months. The majority of people who have mono recover within two to four weeks, and 50 percent can return to regular activities in two weeks, according to the Cleveland Clinic.

An illness called chronic EBV infection can occur if symptoms last for more than six months. EBV will remain dormant in your blood cells for the rest of your life, and it can occasionally reactivate without symptoms. It’s possible to spread the virus to others through contact with your saliva during this time.

EBV also establishes a lifelong, inactive infection in your body’s immune system cells. In some very rare cases, people who carry the virus develop either Burkitt’s lymphoma or nasopharyngeal carcinoma, which are both rare cancers. EBV appears to play a role in the development of these cancers. However, EBV is probably not the only cause.

How can I prevent mono?

Mono is almost impossible to prevent. This is because healthy people who have been infected with EBV in the past can carry and spread the infection periodically for the rest of their lives. Almost all adults have been infected with EBV by age 35 and have built up antibodies to fight the infection. People normally get mono only once in their lives.

Content licensed from:

Written by: Jacquelyn Cafasso
Published on Aug 20, 2012
Medically reviewed on Jul 21, 2017 by Shuvani Sanyal, MD

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
Condition & Treatment Search
Symptom Search
Drug Search



Discounts & Benefits

From companies that meet the high standards of service and quality set by AARP.

Member Benefits AT&T Wireless Cell Phone

Members save 10% on the monthly service charge of qualified AT&T wireless plans.

Member Benefit AARP Regal 2

Members pay $9.50 for Regal ePremiere Tickets purchased online.

Walgreens 1 discount membership aarp

Members earn points on select Walgreens-brand health and wellness products.

Member Benefits

Join or renew today! Members receive exclusive member benefits & affect social change.