Mononucleosis: symptoms and treatments of kissing disease

Infectious mononucleosis is a disease caused by the Epstein-Barr virus. Mononucleosis mostly affects teenagers and young adults, but it can also affect children. In the latter, it is most often silent and therefore undetected.

What is Mononucleosis?

Mononucleosis is most often manifested by sore throats, headaches, extreme fatigue, loss of appetite, and feeling weak throughout the body. The degree of fatigue, especially in the acute phase, can vary greatly from one person to another. Some hardest-hit people have to stop their activities for a few weeks. 

Sport is in any case not recommended for everyone, during the acute phase, because of the risks to the spleen.

It is also called kissing disease, because most of the time, the virus is transmitted through saliva. However, kissing is far from always the cause (eating with the same cutlery, sharing a toothbrush, etc. can also promote the transmission of the virus, as can droplets of saliva ejected into the air during a coughing effort for example). In the end, sick people generally don’t know how they got the disease, but that’s not the most important thing!

Mononucleosis owes its name to the fact that the virus causes an overgrowth of white blood cells called monocyte lymphocytes or monocytes (lymphocytes, which have only one nucleus) in the blood.

See symptoms of mononucleosis.

Is it possible to have mononucleosis and not know it?

It’s possible. Most of the time, when Epstein-Barr virus infection occurs in young children, the symptoms are so mild that they go unnoticed. In addition, they can be easily confused with the many other minor sore throats experienced during early childhood. 

On the other hand, when the first contact with the virus is made in adolescence or early adulthood (15-25-year-olds are the most affected), the infection is accompanied 1 in 2 times by mononucleosis. . The symptoms are usually much more severe. It is not known why some develop it and others do not. One thing is certain, though: if you’ve had mononucleosis, you won’t get it a second time.

How is mononucleosis caught? Is it very contagious?

The Epstein-Barr virus is very contagious, but still less than the common cold because it does not cause sneezing. It is transmitted by saliva, therefore by kisses, exchanges of utensils, soiled objects, or from mother to child.

An infected person is contagious from the moment they are infected. It is therefore during the incubation period: 4 to 6 weeks before the onset of symptoms. Once cured, the person remains contagious for several months. 

The risk of contagion is however higher in the first weeks of the disease when there is a fever and a sore throat. Moreover, parents are asked not to put their child or teenager in class during this period. In adults, a work stoppage can be prescribed as long as the symptoms are present.

How long does mononucleosis last?

After entering the body, the virus first proliferates in the mouth. It then goes to the lymph nodes and the blood. 4 to 6 weeks pass between the moment the virus enters the body and the appearance of symptoms: this is the incubation period.

Acute symptoms last 2 to 3 weeks. A state of fatigue may persist for several months.

Most infectious mononucleosis will heal in three to five weeks, with fatigue lasting a few more weeks.

Then, the virus remains “hidden” in the immune system without causing symptoms and without talking about it again (except in the case of immunosuppression)

How to identify mononucleosis?

The doctor takes a sample of secretions from the throat to distinguish infectious mononucleosis from bacterial angina (angina or sore throat).

Blood tests are requested to confirm the diagnosis of mononucleosis: they look for the presence of specific anti-Epstein Barr virus (EPV) antibodies. This excludes the possibility that the symptoms are caused by another disease (cytomegalovirus or CMV infection, toxoplasmosis, etc.). 

This distinction is essential in pregnant women in particular: in fact, EPV is not dangerous for the fetus, whereas CMV and the parasite responsible for toxoplasmosis both are.

The doctor also asks (via a blood test):

  • a Blood Formulation Count (NFS) which makes it possible to find the transient increase in monocyte or monocyte lymphocytes;
  • hepatic enzymes: they are willingly increased, in a moderate way.

For people who have had unprotected sex, it may be appropriate to also be tested for human immunodeficiency virus (HIV). Indeed, the first symptoms of HIV infection can resemble those of mononucleosis.

Other illnesses associated with Epstein-Barr virus

This virus is involved in the appearance of Burkitt’s lymphoma (read the article), a type of cancer that forms in white blood cells. This lymphoma is rare in the West, but endemic in Africa. 

In the West, it only occurs in people with very weak immune systems (for example, those who received anti-rejection drugs after an organ transplant or chemotherapy). In Asians (Southeast Asia, China), Epstein-Barr virus infection is still implicated in nasopharyngeal cancer.

See the section “How to treat mononucleosis?”

Concretely, there is no specific treatment to cure mononucleosis, but certain drugs help to relieve the symptoms.

What are the causes of mononucleosis?

Mononucleosis is caused by infection with the Epstein-Barr virus. It is an extremely widespread virus, which is transmitted by saliva but does not always lead to infection. 

It is even harmless in the majority of cases, and “colonizes” us without even realizing it. Indeed, from the age of 5 years, 50% of individuals are carriers of the Epstein-Barr virus. In adulthood, the percentage is 90%. In some cases, without knowing why, the first infection with this virus causes mononucleosis.

Antibodies against this virus can be detected in the blood of these people and this protection is long-lasting. Once infected, the person keeps the virus in his body all his life, without having any symptoms. 

She doesn’t relapse. Nevertheless, if a person later becomes immunocompromised for whatever reason, reactivation of the virus becomes possible and it can take a serious, complicated form.

What are the possible complications of mononucleosis?

Although it induces the proliferation of certain blood cells, mononucleosis is a mild disease in the vast majority of cases. Complications are rare, but can still be very serious.

The most serious complication is the rupture of the spleen (a small organ located in the left part of the abdomen and which plays a role in the purification of the blood). The infection can cause swelling of the spleen (splenomegaly). This can then break spontaneously or after a shock, even slightly. This occurs rarely (0.5% to 1% of cases), but the risk is real. 

This is why demanding sports and contact sports are contraindicated for people who have mononucleosis. When the spleen is swollen, a sharp pain localized to the upper and left of the abdomen is then felt. This situation requires emergency treatment. Rupture of the spleen leads to bleeding in the abdominal cavity and pain throughout the abdomen. It can be fatal and surgery is required.

In some cases, the virus induces a large enlargement of the tonsils, which can obstruct the airways and cause significant difficulty in breathing (respiratory distress).

The liver, nervous system, and red blood cells can also be the target of complications (hepatitis, jaundice, encephalitis, meningitis, hemolytic anemia, the proliferation of white blood cells, etc.).

Immunocompromised people are more at risk of developing these complications.

It is rare to hospitalize a person with infectious mononucleosis, except in the event of a complication.

People at risk of mononucleosis

Teenagers and young adults, although the disease can occur at any age.

Mononucleosis risk factors

The symptoms of mononucleosis would be greater in societies where hygiene measures are predominant. Indeed, the infection is then transmitted later in life (during adolescence rather than during childhood). 

However, when contracted at a young age, the infection causes far fewer symptoms and often even goes unnoticed.

Can mononucleosis be prevented?

There is no way to prevent infectious mononucleosis. There is also no vaccine against the Epstein-Barr virus.

People whose health is very fragile and who have never had mononucleosis have an interest in adopting various measures when they meet people with mononucleosis or who have had it in the previous months.

To avoid contagion:

  • avoiding kisses on the mouth with the person with mononucleosis;
  • refrain from sharing kitchen utensils, glasses, and dishes with an infected person (and clean them well);
  • not sharing food;
  • wash your hands well;
  • protect against sneezing and coughing.

How to recognize mononucleosis?

What are its signs and symptoms?

All the answers can be found in this article.

How to recognize mononucleosis?

The symptoms of mononucleosis are:

  • extreme tiredness;
  • swelling and tenderness of the lymph nodes in the neck: many of them may swell at this level;
  • bouts of fever up to 40.5 ºC (105 ºF) and often accompanied by chills. Fever and chills can last one to two weeks;
  • a pronounced sore throat (which can go, in the extreme, to the inability to swallow). The throat is red with white deposits, even membranes;
  • headaches ;
  • loss of appetite;
  • sometimes generalized muscle pain and joint pain;
  • a rash may appear, most often after taking antibiotics;
  • an increase in the size of the spleen is sometimes perceptible by the doctor (by feeling the abdomen).

Fever and sore throat last 2-3 weeks, but fatigue may persist for several months.

Important. In case of acute localized pain in the upper and left abdomen, consult a doctor without delay. This could mean that the spleen is swollen and susceptible to rupture.

This sheet details the different ways to cure mononucleosis, as well as the drug treatments.

Check out all the information below.

Mononucleosis treatments

How to cure mononucleosis?

There is no specific treatment to cure mononucleosis. This is a mild illness that usually goes away on its own after 4-8 weeks, although fatigue may persist for several months. The goal of treatment is therefore to provide supportive care until recovery.

Some tips for a good recovery


Observe a good period of rest (some people will need to leave school or work for a few days or weeks) and gradually resume their previous activities. You have to know how to listen to your body (and in particular its fatigue) so as not to ask too much of it, at the risk of delaying healing.

To drink

Drink plenty of water, broth, and juices to prevent dehydration. Attention, alcohol is not authorized as much as the liver can be affected.


To relieve sore throats, gargle with a saltwater solution (½ tsp salt in a glass of water) several times a day.

Prioritize cold foods

Drinking and eating cold or even frozen foods. When they are not well supported, avoid spicy or acidic foods which further irritate the throat.

Pay attention to the ambient air

The ambient air must not be too dry or too hot. Ideally, the temperature should therefore be below 19°C, with a humidity of 55%. 

And to reduce the concentration of microbes in the room where the patient is resting, it is imperative to ventilate (and therefore open the windows wide) for at least 20 minutes, every day and in all weathers.

Balanced diet

Adopt a balanced diet to help the body recover from the virus (see How to eat well?).

Precautions in case of mononucleosis

  • Give up strenuous sports and contact sports for at least 2 months to avoid rupture of the spleen. The spleen remains fragile even if it is not swollen;
  • avoid lifting heavy objects for at least 2 months to avoid rupture of the spleen;
  • precautions to be taken also for those around you;
  • the risk of transmission of the virus to his relatives is real. To limit this risk, wash your hands often with soap, use a single-use handkerchief to blow your nose, sneeze, or cough (and wash your hands thoroughly afterward), do not kiss anyone as long as there is a risk of contagion, do not share food or cutlery or toiletries and disinfect any object used by the family (such as a telephone, computer keyboard, etc.).

Medicines to relieve symptoms

If needed, medication can help treat complications or relieve symptoms, if they are severe.


To relieve fever, headaches, throat pain, and body aches, the doctor may advise taking paracetamol or, if this is not possible, anti-inflammatories which also have an analgesic and antipyretic effect (against fever), such as ibuprofen. 

Warning: aspirin is strongly discouraged in cases of viral infections for children under 16, as it can cause Reye’s syndrome, a rare but serious condition that can cause neurological sequelae and/or liver damage, or even lead to death.


Some people affected by mononucleosis simultaneously develop a bacterial infection of the throat, sinuses, or tonsils. Certain types of antibiotics, such as ampicillin and amoxicillin, should be avoided, however, as they can cause a skin reaction all over the body in people with mononucleosis. 

A skin reaction to an antibiotic that occurs during mononucleosis does not necessarily mean that the person is allergic to that drug.


Corticosteroids are not prescribed automatically. They are sometimes prescribed for abnormal enlargement of the tonsils (which risks obstructing the airways), or to treat other serious complications, but the analysis of several studies looking at the use of corticosteroids against symptoms of infectious mononucleosis versus placebo did not allow us to find sufficient evidence of their benefit in this indication. Additionally, there is a lack of research on side effects and long-term.

What are the complementary approaches that can be implemented to treat mononucleosis?

Discover our advice in this article.

Complementary approaches to treat mononucleosis

Rest is the main treatment. No specific complementary approach has been studied.

To learn about the basic elements that promote good immune system health (sleep, physical activity, stress control, etc.), see our Strengthening your immune system fact article.

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