Mono, or infectious mononucleosis, 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 refer to it as “the kissing disease.”

Many people develop EBV infections as children after age 1. In very young children, symptoms are usually nonexistent or so mild that they aren’t recognized as mono.

Once you have an EBV infection, you aren’t likely to get another one. Any child who gets EBV will probably be immune to mono for the rest of their life.

However, plenty of children in the United States and other developed countries don’t get these infections in their early years. According to the Centers for Disease Control and Prevention (CDC), mono occurs 25 percent of the time when an adolescent or young adult is infected with EBV. For this reason, mono affects mainly high school and college students.

People with mono often have a high fever, swollen lymph glands in the neck and armpits, 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 1 to 2 months.

Other symptoms may include:

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 1 or 2 weeks of home treatment such as resting, getting enough fluids, and eating healthy foods, see your doctor.

The incubation period of the virus is the time between when you contract the infection and when you start to have symptoms. It lasts for 4 to 6 weeks. The signs and symptoms of mono typically last for 1 to 2 months.

The incubation period may be shorter in young children.

Some symptoms, like sore throat and fever, typically lessen after 1 or 2 weeks. Other symptoms such as swollen lymph nodes, fatigue, and an enlarged spleen may last a few weeks longer.

Mononucleosis is usually caused by EBV. The virus is spread through direct contact with saliva from the mouth of an infected person or other bodily fluids, such as blood. It’s also spread through sexual contact and organ transplantation.

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 4 to 8 weeks for symptoms to develop after you’re infected.

In adolescents and adults, the infection sometimes doesn’t cause noticeable symptoms. In children, the virus typically causes no symptoms, and the infection often goes unrecognized.

Epstein-Barr virus (EBV)

The Epstein-Barr virus (EBV) is a member of the herpes virus family. According to the CDC, it’s one of the most common viruses to infect humans around the world.

After you become infected with EBV, it remains inactive in your body for the rest of your life. In rare cases it can reactivate, but there usually won’t be any symptoms.

In addition to its connection with mono, experts are looking into possible links between EBV and conditions such as cancer and autoimmune diseases. Learn more about how EBV is diagnosed with the Epstein-Barr virus test.

Mono is contagious, although experts aren’t really sure how long this period lasts.

Because EBV sheds in your throat, you can infect someone who comes into contact with your saliva, such as by kissing them or sharing eating utensils. Due to the long incubation period, you may not even be aware you have mono.

Mono can continue to be contagious for 3 months or more after you experience the symptoms. Find out more about how long mono is contagious.

The following groups have a higher risk for getting mono:

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.

Because other, more serious viruses such as hepatitis A can cause symptoms similar to mono, your doctor will work to rule out these possibilities.

Initial exam

Once you visit your doctor, they’ll normally ask how long you’ve had symptoms. If you’re between ages of 15 and 25, your doctor might also ask if you’ve been in contact with any individuals who have mono.

Age is one of the main factors for diagnosing mono along with the most common symptoms: fever, sore throat, and swollen glands.

Your doctor will take your temperature and check the glands in your neck, armpits, and groin. They might also check the upper left part of your stomach to determine if your spleen is enlarged.

Complete blood count

Sometimes your doctor will request a complete blood count. This blood test will help determine how severe your illness is by looking at your levels of various blood cells. For example, a high lymphocyte count often indicates an infection.

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 can’t confirm an infection with EBV, but the result suggests that it’s a strong possibility.

The monospot test

Lab tests are the second part of a doctor’s diagnosis. One of the most reliable ways to diagnose mononucleosis is the monospot test (or heterophile test). This blood test looks for antibodies —these are proteins your immune system produces in response to harmful elements.

However, it doesn’t look for EBV antibodies. Instead, the monospot test determines your levels of another group of antibodies your body is likely to produce when you’re infected with EBV. These are called heterophile antibodies.

The results of this test are the most consistent when it’s done between 2 and 4 weeks after symptoms of mono appear. At this point, you would have sufficient amounts of heterophile antibodies to trigger a reliable positive response.

This test isn’t always accurate, but it’s easy to do, and results are usually available within an hour or less.

EBV antibody test

If your monospot test comes back negative, your doctor might order an EBV antibody test. This blood test looks for EBV-specific antibodies. This test can detect mono as early as the first week you have symptoms, but it takes longer to get the results.

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 1 to 2 months.

Contact your doctor if your symptoms get worse or if you have intense abdominal pain. Learn more about treating mono.

Treatment at home 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 remedies that may ease symptoms include:

  • getting a lot of rest
  • staying hydrated, ideally by drinking water
  • eating warm chicken soup
  • boosting your immune system by eating foods that are anti-inflammatory and rich in antioxidants, such as leafy green vegetables, apples, brown rice, and salmon
  • using OTC pain medications such as acetaminophen (Tylenol)

Never give aspirin to children or teenagers because it could lead to Reye’s syndrome, a rare disorder that can cause brain and liver damage. Find out more about home remedies for 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 1 month before doing any vigorous activities, lifting heavy objects, 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:

Mono symptoms like fatigue, fever, and a sore throat usually last for a few weeks. In rare cases, the symptoms can flare up months or even years later.

EBV, which usually is what causes a mono infection, remains in your body for the rest of your life. It’s usually in a dormant state, but the virus can be reactivated.

Mono mostly affects people in their teens and 20s.

It occurs less commonly in adults over the age of 30. Older adults with mono will usually have a fever but may not have other symptoms such as a sore throat, swollen lymph nodes, or an enlarged spleen.

Children can become infected with mono by sharing eating utensils or drinking glasses, or by being near an infected person who coughs or sneezes.

Because children may only have mild symptoms, such as a sore throat, a mono infection may go undiagnosed.

Children who are diagnosed with mono can usually continue to attend school or day care. They may need to avoid some physical activities while they recover. Children with mono should wash their hands frequently, especially after sneezing or coughing. Learn more about the mono symptoms in children.

Most people are infected with EBV early in life. As with older children, toddlers can become infected with mono by sharing eating utensils or drinking glasses. They can also become infected by putting toys in their mouths that have been in the mouths of other children with mono.

Toddlers with mono rarely have any symptoms. If they do have a fever and sore throat, it may be mistaken for a cold or the flu.

If your doctor suspects your toddler has mono, they will probably recommend that you make sure your child gets rest and plenty of fluids.

Mono is usually caused by EBV, which remains dormant in your body after you recover.

It’s possible, but unusual, for EBV to become reactivated and for the symptoms of mono to return months or years later. Get a better understanding of the risk of mono relapse.

Most people have mono only once. In rare cases, the symptoms can recur due to a reactivation of EBV.

If mono returns, the virus is in your saliva, but you probably won’t have any symptoms unless you have a weakened immune system.

In rare instances, mono can lead to what’s called chronic active EBV (CAEBV) disease. This is a serious condition in which the mono symptoms persist longer than 6 months.

If you are experiencing the symptoms of mono and have had it before, see your doctor.

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 and have built up antibodies to fight the infection. People normally get mono only once in their lives.

The symptoms of mono rarely last for more than 4 months. The majority of people who have mono recover within 2 to 4 weeks.

EBV 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.