Mononucleosis

Mononucleosis is a viral condition often called “mono” or glandular fever. It is usually caused by Epstein-Barr virus, or EBV. EBV is very common and belongs to the herpesvirus family.

The virus mainly spreads through saliva. Mono is sometimes called the “kissing disease,” but kissing is only one way it can spread. Sharing drinks, eating utensils, toothbrushes, or other objects that touch the mouth may also pass it on.

Mono matters because the fatigue can be intense and may last longer than the fever or sore throat. The condition can also enlarge the spleen, an organ under the left side of the ribs that helps filter blood. An enlarged spleen is easier to injure, so sports and heavy physical activity may need to be paused during recovery.

Most people recover without specific antiviral treatment. EBV remains inactive, or dormant, in the body afterward. This does not mean that you remain ill.

Symptoms often develop gradually several weeks after infection. Some people, especially young children, have mild symptoms or none that are noticed.

Typical symptoms include:

• Marked tiredness or weakness
• Fever
• A painful or inflamed throat
• Swollen lymph nodes, especially along the neck
• Enlarged or coated tonsils
• Headache and body aches
• Reduced appetite

Lymph nodes are small parts of the immune system sometimes called glands. They may feel like tender lumps beneath the skin.

Some people develop an enlarged spleen or liver. This may cause discomfort beneath the ribs, although enlargement often causes no obvious symptoms. Mild liver inflammation is common on blood tests. Yellow skin or eyes, known as jaundice, is less common and needs medical assessment.

A blotchy rash can occur. A rash is especially likely if someone with mono takes ampicillin or amoxicillin. This reaction does not always mean the person has a lasting penicillin allergy, but it should be recorded and discussed before future antibiotic use.

The fever and throat symptoms often improve before the fatigue. Tiredness may continue for several weeks and occasionally for months.

Most cases are caused by Epstein-Barr virus. Less often, a similar mono-like condition can result from another infection, such as cytomegalovirus. Testing may be needed when the cause is uncertain.

EBV spreads mainly through saliva. It can also be present in blood and semen, but mono is not usually described as a sexually transmitted infection.

A person may pass EBV before symptoms begin and for months afterward. The virus can later be released in saliva from time to time without causing symptoms. For this reason, it is usually impossible to identify exactly when or from whom an infection was acquired.

Teenagers and young adults are more likely than young children to develop the classic combination of sore throat, swollen neck glands, fever, and fatigue. Having close contact with saliva increases the chance of exposure. Mono is not inherited.

Once a person has had EBV, the virus stays dormant in certain immune cells. Reactivation can happen, but it usually causes no symptoms in people with healthy immune systems.

A clinician may suspect mono from your symptoms and an examination. They may look at your throat and lymph nodes and gently examine your abdomen for signs that the liver or spleen is enlarged.

Blood tests can help confirm the diagnosis. A heterophile antibody test, sometimes called a Monospot test, looks for antibodies often produced during mono. Antibodies are proteins made by the immune system in response to infection.

A heterophile test can be negative early in the illness even when EBV is the cause. It is also less reliable in young children. If the result does not fit the symptoms, EBV-specific antibody tests may be used. These tests look for patterns of antibodies that help distinguish a new infection from an infection that happened in the past.

A complete blood count may show increased lymphocytes, which are a type of white blood cell. Some may have an unusual appearance called atypical lymphocytes. Liver blood tests may also be temporarily abnormal. These findings support the diagnosis but do not confirm EBV by themselves.

Other tests may be considered when symptoms could have another cause, such as strep throat, cytomegalovirus, or acute HIV infection. Ultrasound is not routinely needed just to check spleen size, but imaging may be used if there is concern about an injury or another abdominal problem.

There is no specific cure for typical EBV mononucleosis. Treatment focuses on comfort, hydration, and protecting the spleen while the immune system controls the infection.

Helpful measures may include:

• Resting while symptoms are strongest
• Drinking enough fluid to avoid dehydration
• Using appropriate nonprescription medicine for pain or fever
• Trying cool drinks, warm liquids, or salt-water gargles for throat pain
• Returning gradually to school, work, and normal activity

Follow the medicine label and ask a pharmacist or clinician if you have liver, kidney, stomach, bleeding, or other health problems. Children and teenagers with a viral illness should not take aspirin because of the risk of Reye syndrome, a rare but serious condition affecting the brain and liver.

Antibiotics like amoxicillin or doxycycline do not treat EBV. They are only useful if there is also a bacterial infection. Ampicillin and amoxicillin are generally avoided when mono is suspected because they commonly trigger a rash.

Steroid medicines are not routine treatment for uncomplicated mono. They may be used under close medical supervision for certain serious problems, such as severe tonsil swelling that threatens breathing, major destruction of red blood cells, or a very low platelet count. Antiviral medicines have not shown enough benefit to be routine treatment for typical mono.

Avoid contact sports, collision activities, heavy lifting, and activities with a risk of falling while the spleen may be enlarged. Feeling better does not prove that the spleen has returned to normal. The timing of a safe return to sports should be based on recovery, the activity involved, and medical guidance.

Alcohol is best avoided during the illness, particularly if liver tests are abnormal. Alcohol and excessive amounts of some pain medicines can add stress to an inflamed liver.

Most people recover without major complications. Problems that can occur include:

• Dehydration from fever or painful swallowing
• Temporary liver inflammation or jaundice
• Severe swelling of the tonsils and nearby tissues
• Low platelets, which help blood clot
• Anemia caused by early breakdown of red blood cells
• Inflammation affecting the nervous system or heart

The spleen can become enlarged and, rarely, rupture or tear. A ruptured spleen may cause internal bleeding. Warning signs include sudden or severe pain in the upper left abdomen, pain felt at the left shoulder, faintness, unusual paleness, or severe weakness. This is an emergency.

Breathing difficulty from throat swelling is also an emergency. Most sore throats caused by mono are uncomfortable but do not block the airway.

There is no licensed vaccine that prevents Epstein-Barr virus infection, and mono cannot always be prevented. People can spread EBV without knowing they carry it.

To reduce the chance of passing saliva while you are ill, avoid kissing and do not share drinks, utensils, lip products, toothbrushes, or objects placed in the mouth. Wash reusable cups and utensils normally.

There is no clear point when saliva is guaranteed to contain no virus. Long-term isolation is therefore not practical or generally recommended. Routine handwashing and avoiding saliva-sharing are more useful than trying to disinfect an entire home.

The strongest throat symptoms, fever, and swollen glands often settle within a few weeks. Fatigue may improve more slowly. Some people feel tired for several additional weeks or months, especially when they try to resume a full schedule too quickly.

During recovery, energy may be uneven. You may feel well after resting and then become exhausted after school, work, or exercise. A gradual return to normal activity is often easier than pushing through severe fatigue. Sleep, fluids, regular meals, and temporary adjustments at school or work may help.

Most people eventually return to their previous level of health and activity. Mono does not usually become an ongoing active condition. EBV remains dormant in the body, but this is common and does not mean that symptoms will continue.

The greatest activity-related concern during early recovery is injury to an enlarged spleen. Do not use energy level alone to decide when to restart contact sports or heavy training. Follow the return plan given for your situation.

A second classic episode of mono is uncommon. If similar symptoms return months or years later, another infection or health problem may be responsible and may need assessment.

Arrange a routine medical appointment if you have persistent fever, a severe sore throat, swollen neck glands, or fatigue that is disrupting daily life. Testing may help distinguish mono from strep throat or another infection.

Contact a clinician promptly if you cannot drink enough, are urinating much less than usual, develop yellow skin or eyes, have worsening abdominal discomfort, or are not improving as expected. Ongoing fatigue should also be reviewed if it is severe, getting worse, or lasting longer than expected.

Seek emergency care immediately for:

• Trouble breathing or noisy, strained breathing
• Inability to swallow saliva
• Sudden or severe upper-left abdominal pain
• Abdominal pain with left shoulder pain
• Fainting, marked dizziness, unusual paleness, or confusion

These symptoms may indicate severe throat swelling, internal bleeding, or another urgent problem. Do not drive yourself if you feel faint or seriously unwell.

How long does mono last?

Fever and throat symptoms often improve within two to four weeks. Fatigue can last several weeks longer and sometimes persists for months. Recovery is not identical for everyone, and energy may return gradually.

How long am I contagious with mono?

There is no exact end date. EBV may be present in saliva before symptoms and for months afterward. It can also appear in saliva from time to time later in life. Avoid sharing saliva while you are ill, but prolonged isolation is generally not practical.

Can I go to school or work with mono?

You may be able to return when fever has settled and you feel well enough to participate. You do not usually need to remain away until the virus is gone from saliva. A shorter schedule or lighter workload may be useful while fatigue continues.

Why do I need to avoid sports?

Mono can enlarge the spleen, making it more vulnerable to tearing. Contact sports, heavy lifting, falls, and blows to the abdomen increase that risk. Return gradually and obtain appropriate clearance before restarting higher-risk activities.

Can mononucleosis come back?

A repeat episode of classic EBV mono is uncommon. EBV stays dormant and can reactivate, but reactivation usually causes no symptoms. Similar symptoms later may come from another infection or condition.

Is mononucleosis a sexually transmitted infection?

Mono is mainly spread through saliva and is not usually classified as a sexually transmitted infection. EBV can also be present in semen and may spread during sexual contact, especially when kissing or saliva exposure is involved.