Mononucleosis

Symptoms of mononucleosis

• Extreme fatigue
• Sore throat
• Stuffy, runny nose
• Swollen eyelids
• Small, red bumps on the skin
• Swollen and sensitive lymph nodes on the sides and back of the neck
• High fever, sometimes reaching 40.5°C (104.9°F) late in the day
• Headaches or muscle aches
• Lack of appetite

• Has sharp pain on the upper left side of the abdomen
• Has difficulty breathing due to an extremely sore throat
• Has severe headaches combined with vomiting
• Can’t manage to eat or drink

What is mononucleosis?

Mononucleosis is an illness normally caused by the Epstein-Barr virus, a member of the herpes family of viruses.

The mononucleosis virus is contagious, but not as contagious as the viruses causing the common cold or the flu. It is often transmitted by direct contact with the saliva of an infected person. That’s why mononucleosis is nicknamed the “kissing disease.”

Because mononucleosis doesn’t usually cause much coughing or sneezing, it’s rarely transmitted by airborne droplets. However, you can catch the disease by sharing utensils, glasses, etc.

Once infected with the Epstein-Barr virus, people are then immune to the illness for life. Half of 5-year-old children are believed to have already been exposed to the virus without necessarily developing mononucleosis. Around 90% of adults aged 40 are thought to be immune to the disease.

Potential complications

Mononucleosis is a relatively harmless illness that usually resolves on its own.

It can, however, cause the spleen to swell, making it more fragile. In rare cases, the spleen may rupture. For this reason, children with mononucleosis should not engage in strenuous sports or heavy physical exertion (e.g., heavy lifting) for 3 to 4 weeks.

Other, rarer complications can occur with mononucleosis, such as difficulty breathing, severe headaches with vomiting, a significant decrease in urine output, or jaundice. It’s a good idea to speak to a doctor if new symptoms arise, or if your child seems to be getting worse instead of better.

What to do at home

• Allow your child to rest. Based on the doctor’s recommendations, they will probably have to miss school.
• To relieve pain and fever, give your child acetaminophen (Tylenol^®, Tempra^®) or ibuprofen (Advil^®, Motrin^®). Never give acetylsalicylic acid (ASA), such as Aspirin^®, to a child or teenager.
• Offer them frequent cool drinks, such as water or certain juices (e.g., pear, apple, grape). Avoid carbonated beverages and citrus juices such as orange, lemon, and grapefruit, which can irritate a sore throat.
• Have your child to gargle a few times a day with 2.5 ml (1/2 tsp.) of salt dissolved in a glass of warm water.
• Give them sugar-free hard candies and lozenges containing honey, herbs, or pectin to soothe their sore throat.
• Limit their screen time and suggest other enjoyable activities such as drawing, modelling clay, crafts, simple board games, or reading stories.
• Ensure that your child avoids heavy physical exertion and any kind of strenuous activity or contact sport for at least 3 to 4 weeks.

Treatment

Mononucleosis is a viral infection. That means antibiotics won’t help, unless the virus is complicated by a bacterial infection such as strep throat, sinusitis, or tonsillitis.

If your child has to take antibiotics, make sure they take the medication for the full prescribed period, even if they feel better after a few days. A full course of treatment reduces the risk of bacterial resistance to the prescribed antibiotic.

The doctor will avoid prescribing penicillin if possible, since it causes significant skin reactions in 90% of mononucleosis patients. These tend to resemble allergic reactions, although they are not.

If necessary, the doctor may prescribe corticosteroids, for complications such as severe upper airway obstruction with difficulty breathing, which may occur if tonsils become too swollen. This complication arises in fewer than 3.5% of cases.

Prevention

You can’t prevent an Epstein-Barr virus infection, but you can tell your sick child how to avoid contaminating others.

Here’s how your child can protect those around them:

• Do not share utensils, glasses, or dishes with others.
• Don’t share food.
• Wash hands thoroughly.
• Sneeze into a tissue or the crook of the elbow.

Scientific review: Dr. Anne-Claude Bernard-Bonnin, pediatrician Research and copywriting:The Naître et grandir team Updated: April 2023

Photo: GettyImages/Elena Medoks