Mononucleosis in Adults: Understanding Its Specific Characteristics and Finding Out More

After infection, the virus enters the body and infects certain white blood cells, specifically B lymphocytes. These immune cells then become hosts for the virus, which multiplies within them before spreading throughout the body. This viral invasion triggers a response from our immune defences, which explains the characteristic symptoms of this condition.

The Epstein-Barr virus has a distinctive feature: once contracted, it remains dormant in the body for life. It is estimated that around 90% of the world’s adult population carries the virus, most often following an infection during childhood or adolescence.

The incubation period for the disease is long, generally lasting 4 to 6 weeks. It is therefore difficult to identify the possible source of infection. During this period, the virus is in a latent phase, meaning that the carrier can transmit the virus to others without realising it, which contributes to its widespread transmission.

Mononucleosis in adults has specific characteristics that distinguish it from the juvenile form. The symptoms are more severe, as are the duration of the illness and the so-called convalescence period, which can last for several months. This difference is partly explained by the immune response of a more robust adult immune system when first encountering the virus.

Mononucleosis is caused by the Epstein-Barr virus. However, several factors can influence the likelihood of developing the condition in adulthood, as well as the severity of the symptoms.

Factors that Increase the Risk of Infection With the Epstein-Barr Virus

A Lack of Prior Immunity: People who have never been exposed to the virus during childhood remain susceptible to contracting the illness.

A Weakened Immune System: A weakened immune system, whether due to chronic fatigue, prolonged stress, nutritional deficiencies, or certain medical conditions, makes the body less able to defend itself. 

Environmental Factors: Crowded conditions in enclosed spaces, communal living, lack of sleep, and an unbalanced diet can create favourable conditions. These factors weaken the body and facilitate the transmission of the virus between individuals.

Viral Reactivation of Mononucleosis in Adults

In some adults who are already carriers of the virus, it can reactivate after a few years. This reactivation usually occurs during periods that are quite intense and challenging for the immune system. Examples include periods of extreme fatigue or intense stress. Whilst this is less common than a primary infection, this reactivation causes symptoms identical to those of mononucleosis, although they are generally less severe.

The symptoms of mononucleosis in adults have certain characteristics that distinguish them from the juvenile form. The symptoms are often more severe and the recovery period longer.

• Severe and Persistent Fatigue: This is the most characteristic symptom of infection with the Epstein-Barr virus. This fatigue is not like temporary tiredness and is genuinely debilitating in adults. It sets in gradually until it becomes overwhelming and affects even the simplest daily activities. The fatigue associated with mononucleosis persists even after several nights’ rest. This fatigue can last for several weeks, or even several months, even after the other symptoms have disappeared. We have an article on natural remedies for combating fatigue

• A High Fever: This usually appears at the start of the infection. The fever typically lasts for one to two weeks, sometimes longer. It is accompanied by chills, profuse night sweats and a general feeling of malaise

• Swollen lymph nodes: This is a characteristic sign of mononucleosis in adults. It is the immune system that is activated and takes over to defend the body. These lymph nodes are mainly located in the neck, behind the ears, under the jaw and sometimes as far as the armpits or groin. They become palpable, tender to the touch and can grow to the size of a walnut. In the case of mononucleosis, this condition can persist for up to several weeks, compared with a typical infection

• Enlargement of the Spleen: Around 50% of affected adults experience splenomegaly, i.e. an enlarged spleen. This organ, located beneath the ribs on the left-hand side, sometimes increases considerably in size, causing a feeling of heaviness or pain in the upper left part of the abdomen. This complication requires particular vigilance, as an enlarged spleen becomes more fragile and is at risk of rupturing even with a minor impact

• Skin Symptoms: Some adults develop a skin rash, particularly if they have taken antibiotics from the penicillin group before a correct diagnosis of mononucleosis was made. These rashes take the form of small red spots which may cover a large part of the body and be accompanied by itching

• Liver Symptoms: In some cases, the virus affects the liver and causes mild hepatitis. This manifests as a yellowish discolouration of the skin and the whites of the eyes, dark urine, and pale stools. Pain in the upper right side of the abdomen may also occur

• Loss of Appetite: The combination of fever, a painful sore throat and general malaise often leads to a significant loss of appetite. This can result in noticeable weight loss during the acute phase of the illness

• Persistent Headaches: These frequently accompany the other symptoms and can be severe

If you experience symptoms suggestive of mononucleosis, it is essential to see a doctor promptly. Diagnosis is based on a clinical examination and specific blood tests, which detect the presence of antibodies against the Epstein-Barr virus and identify characteristic changes in white blood cells.

Prevention of mononucleosis relies mainly on hygiene measures and lifestyle habits that reduce the risk of transmitting the virus.

• Avoid Sharing Personal Items: Do not share your glass, water bottle, cutlery or toothbrush with other people. This simple but effective precaution significantly reduces the risk of transmission via saliva. In social situations where sharing is common, keep this hygiene rule in mind

• Boost Your Immune System: A body with optimal defences is better able to resist viral infections. Make sure you maintain a balanced diet, rich in fruit and vegetables which provide vitamins and antioxidants. Sleep also plays a vital role in maintaining immunity. Aim for seven to eight hours’ sleep per night, keeping to a regular schedule, to ensure restorative sleep. Managing chronic stress through relaxation techniques, meditation, or regular physical activity also helps to preserve your natural defences

• Maintain Good Hand Hygiene: Wash your hands regularly with soap, particularly before meals and after coming into contact with shared surfaces. This simple step helps to limit the spread of many pathogens, including the Epstein-Barr virus

• Be Vigilant When You’re Tired: When you’re going through periods of extreme tiredness, intense stress, or overwork, your susceptibility to infections increases. During these challenging times, be extra vigilant about hygiene measures and make sure you get plenty of rest

• Inform Those Around You if You Fall Ill: If you are diagnosed, let the people with whom you have been in close contact over the previous few weeks know. This openness enables them to be on the lookout for any symptoms that may develop and to seek medical advice promptly if necessary

• Adjust Your Lifestyle: Limit your consumption of alcohol and tobacco, as these can damage the mucous membranes and weaken the immune system. Regular, moderate physical activity naturally strengthens the body’s defences and improves resistance to infections

If you are taking a dietary supplement, for example to support the immune system, it is essential to follow the recommendations for use of the supplement in question. If you have a fever, aspirin is contraindicated due to the risk of liver complications associated with mononucleosis in adults. However, the first step to take if mononucleosis is suspected should be to consult a doctor. Medical advice is essential to confirm the diagnosis, assess the severity of symptoms and tailor treatment, particularly in cases of severe fatigue or prolonged fever.

There is no specific treatment. The measures recommended by your doctor will mainly focus on managing the symptoms. Rest remains the cornerstone of the treatment plan. Staying hydrated is important. We advise you to drink water regularly. Adding electrolytes to your drink is a good way to ensure your body stays properly hydrated. If you’re having difficulty swallowing, opt for cool liquids, which can provide temporary relief from pain.

Your immune system can be supported by taking dietary supplements such as the energy and immunity supplement. Similarly, if you are experiencing stress or chronic fatigue, it may be worth consulting your doctor or a naturopath to review your lifestyle habits.

Guillaume is a pharmacy technician specialising in dermocosmetics. With more than ten years’ experience in the pharmacy sector, he now supports health and cosmetics brands with writing blog articles. Having studied naturopathy, he takes part in podcasts to explain health and cosmetics in accessible terms.