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Mononucleosis, infectious mononucleosis, or “mono”, refers to a group of symptoms that can occur after infection with the Epstein-Barr virus (EBV). Mono symptoms include fatigue, a fever, and a sore throat.

According to the Centers for Disease Control and Prevention (CDC), most people experience infection with EBV, also known as glandular fever, at some point in their lives. Many do not develop symptoms of mono, but they become carriers.

Symptoms can vary between age groups. In young children, any symptoms that appear tend to be mild. In teenagers and young adults, however, they can be more severe.

Here, learn more about the symptoms and treatment of mono.

Anyone who has a fever of 104 degrees Fahrenheit or above should see a doctor.Share on Pinterest
Image credit: solidcolours/istock.

The classic symptoms of mono are:

However, the symptoms vary widely between different age groups.

Teens and young adults

People aged 15–24 years are most likely to develop the classic symptoms of mono. They also tend to have the most severe symptoms.

Symptoms often last 2–4 weeks, but they can persist for longer. Fever, sore throat, and other common symptoms may last for several days and then gradually get better.

However, the tiredness can last for weeks or months after other symptoms have gone.

Why symptoms affect teens and young adults more severely remains unclear.

If kissing is a factor in spreading mono, it may be that the higher levels of saliva exchange lead to more severe symptoms.

Another theory is that younger children gradually build up an immunity to the virus if exposure occurs from a lower age, as happens in some countries.

In the United States, exposure to EBV is less common during infancy and young childhood. An adolescent with no previous exposure to the virus may be more vulnerable, as their immune system is less able to repel the attack.

Young children

Children often do not have classic symptoms, or they may have mild symptoms that resemble those of a common cold or the flu.

It is unclear how they get the virus. One possiblity is that parents, as carriers, pass the virus on to their children when it reactivates and sheds. The amount of virus spread from a parent’s past infection may be lower, causing fewer, milder symptoms in a child.

If a child has mild mono symptoms, a parent may think this is a cold or flu, especially if fever and a sore throat are the main symptoms.

Older adults

A study from 2006 notes that mono is less common in adults aged over 40 years. Adults may not experience the classic symptoms of a red throat and swollen lymph nodes.

Instead, liver problems may occur. A fever with liver inflammation can make mono harder to spot in this age group. Muscle aches may also be more common in this group, according to one older study.

When to see a doctor

Many illnesses cause fever and sore throat, particularly colds, flu, and common viruses.

Mono can resemble other illnesses, so people should contact a doctor if they have concerns about symptoms that may indicate mono.

Parents should call a doctor if a child:

  • shows unusual behavior
  • does not want to eat
  • has a severe headache or sore throat
  • has a rash
  • has a seizure
  • has a temperature of 104° Fahrenheit or above
  • shows signs of dehydration, such as not urinating

Those with symptoms of a ruptured spleen should seek emergency care immediately.


In a teenager or young adult with classic symptoms, a doctor can usually diagnose mono through a physical examination.

However, symptoms can be less obvious in younger children and older adults, so additional testing may be needed.

Blood tests can identify whether or not a person has had a recent or past infection with EBV.

Mono is a virus, so antibiotics cannot treat it.

Doctors recommend managing symptoms through:

  • pain relievers and fever reducers, such as ibuprofen or acetaminophen, which is available to buy online.
  • salt water gargles for a sore throat
  • rest
  • avoiding sports until symptoms are gone

Infectious mononucleosis, also known as glandular fever, can emerge as a result of infection with EBV, or herpes virus 4.

Mono refers to the symptoms of infection, and EBV is the most common cause.

Many people are infected with EBV but never experience symptoms of mono, or the symptoms are very mild, and similar to those of another common illness, such as a cold or flu.

Adolescents and young adults are most likely to have noticeable symptoms, and mono is common among college students.

Even in a person with no symptoms, the virus can be active or reactivated at a later date. When it is active, symptoms may or may not appear, and the virus can be passed on to another person. This person may develop symptoms of mono.

Once a person has experienced symptoms of mono, they are unlikely to have them again.

While EBV is the most common cause of mono, other infections can cause mono symptoms.

These include:

Mono is often called the “kissing disease,” but it is not only spread by kissing. Sharing drinks, toothbrushes, or a plate of food can spread it. It can also be passed on through breast milk, other bodily floods such as blood or semen, or through blood transfusions.

The consquences are not usually serious, but the symptoms can be debilitating while they last, and it can take a long time to recover, especially from the fatigue.

Risk factors

The EBV virus, which causes mono, is most often spread through saliva.

Many people contract the virus during childhood and never notice any symptoms. Once the virus enters the body, it stays there forever, and it can occasionally reactivate at a later time.

The reactivated virus can spread to others through saliva, so a person can catch mono from someone who has no signs of illness.

The following can increase the risk:

  • sharing drinks, toothbrushes, or anything that touches the mouth and saliva
  • sexual contact
  • having a blood transfusion
  • receiving a transplanted organ

A person whose immune system is compromised has a higher risk of:

  • developing symptoms on a first exposure to EBV
  • the virus reactivating and causing a second bout of mono

Mono is most common in teens and young adults. Most people will not have it a second time.

The incubation period for mono is around 6 weeks.

During this period, from the time of infection until symptoms appear, a person is contagious. They appear healthy, but they can spread mono to others.

When symptoms emerge, they may be severe for a few days, then gradually get milder.

Most people feel better after 2–4 weeks, but the fatigue can last for several weeks or months.

Serious complications are rare, but 0.5% of people may experience a ruptured spleen. This can be fatal.

Symptoms of a ruptured spleen include:

  • pain in the upper left abdomen
  • pain in the left shoulder that feels worse when breathing in
  • pain in the left chest area
  • a sudden drop in blood pressure, which may cause fainting, confusion, dizziness, or paleness

A blow to the abdomen near the spleen may cause a swollen spleen to rupture. For this reason, athletes should avoid contact sports for at least 3 to 4 weeks after getting mono.

If mono causes liver problems, jaundice may occur. The whites of the eyes or the skin appear yellow. In most cases, the liver inflammation will improve on its own as the body clears the infection.

In rare cases, mono can also cause:

  • blood problems such as anemia or low platelet counts
  • inflammation of the heart muscle
  • inflammation of the brain and spinal cord membranes, known as meningitis
  • encephalitis, or inflammation of the brain
  • Guillain-Barre syndrome
  • breathing problems due to swollen tonsils

These problems are rare. They are more likely in a person with a weakened immune system, due, for example, to HIV or AIDS, some kinds of cancer treatment, or having had an organ transplant.

There is no proven way to prevent mono, but a few simple tips can help avoid it:

  • washing hands after using the bathroom and before eating
  • coughing or sneezing into a sleeve or tissue and washing hands afterward
  • avoiding people who have mono or symptoms of mono until they recover
  • staying home from work or school if you have symptoms
  • not sharing objects that come into contact with the mouth

Mono symptoms may interfere with life for several days or weeks, but most people recover without any long-term problems. Managing symptoms with self-care and rest is often the best way to deal with mono.