Symptoms of Mono in Kids

Symptoms of mononucleosis in kids include flu-like symptoms, fever, and swollen lymph nodes. Infectious mononucleosis, also known simply as mono, is common in teenagers and college students. This viral illness is very contagious, and many kids show no symptoms. 

Mono is spread by saliva and other bodily fluids such as blood and semen. It is usually caused by the Epstein-Barr virus (EBV) and sometimes the cytomegalovirus (CMV). Once your child recovers from mono, the virus stays dormant in their body. While many of the symptoms are similar to mono in adults, the virus can present differently in children. 

Teenage girl sick in bed

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Frequent Symptoms

It’s common to mistake your child’s mono symptoms for the flu or strep throat. Mono symptoms can last several weeks, so if your child does not show any improvement after a few days, talk with your healthcare provider about a possible mono diagnosis. 

While each case of mono is unique, some of the most common symptoms include:

  • Swollen lymph nodes: Swollen lymph nodes are a common symptom of mono and occur in almost 90% of cases. When your child’s lymph nodes are swollen, it means their immune system is fighting off an infection. 
  • Fever: A mild to moderate fever is another common mono symptom. Your healthcare provider will most likely recommend giving your child acetaminophen or ibuprofen to manage the fever and discomfort. 
  • Fatigue: While most mono symptoms last two to four weeks, the fatigue can linger for weeks to months. If your child is so tired that they no longer want to get out of bed or eat meals, talk with your practitioner.
  • Sore throat: Most children with mono report a sore throat. This may be due to swelling of the lymph nodes and tonsils, making swallowing painful. 
  • Body aches: It’s common for children and teens to experience muscle aches with mono. Encourage rest, liquids, and pain medicine if needed. 
  • Loss of appetite: Many children lose their appetite when they are ill with mono. This could be due to fatigue or painful swallowing. Encourage your child to drink as much fluid as possible to prevent dehydration.
  • Enlarged spleen: It’s common for children and teens with mono to have an enlarged spleen during the illness. When the spleen is enlarged, it may start to filter out normal red blood cells and platelets, leading to their low levels in the blood. In most cases, the spleen returns to its normal size on its own.
  • Swollen liver: It’s possible for children with mono to have a mildly inflamed liver. This usually resolves on its own once they start feeling better. If you notice a yellowing of your child’s eyes or skin, known as jaundice, call your healthcare provider. 

Rare Symptoms

Most people are familiar with the common symptoms of mono like fatigue and fever, but you may not be aware of these rare symptoms:

  • Anemia: Mild anemia can occur when your child has mono, but it generally improves on its own within one to two months. This is usually the result of an inflamed spleen.
  • Thrombocytopenia: It’s possible for your child to experience a low platelet count during a mono illness. Platelets are the cells responsible for clotting your blood. This also usually resolves on its own. 
  • Difficulty breathing: You may notice that your child’s tonsils appear swollen. This is normal during mono. In rare cases, the tonsils can become so swollen that they begin to block your child’s airway. Any difficulty breathing requires emergency treatment. 


Complications of mono include conditions that can happen as a result of the virus. These are not symptoms but rather additional illnesses that may occur. Most children will not experience these complications, but it is helpful to be aware of them:

  • Ruptured spleen: When your child’s spleen is enlarged due to mono, they are more at risk of experiencing a ruptured spleen. This is a serious complication and requires emergency surgery. To help avoid a spleen rupture, your pediatrician will recommend no contact sports or heavy lifting for at least four weeks. 
  • Guillain-Barre syndrome: This autoimmune syndrome is a rare complication of mono which occurs when a child’s peripheral nerves are damaged by the virus. When the nerve endings are damaged, they cannot transmit signals normally, and this results in temporary paralysis. 
  • Meningitis: Meningitis occurs when the membranes and fluid that surround the brain and spinal cord are inflamed. This inflammation can be triggered by a viral infection like an EBV infection. 
  • Encephalitis: Inflammation of the brain is known as encephalitis. It can manifest as behavioral changes, seizures, and loss of consciousness. 
  • Myocarditis: Myocarditis refers to inflammation of the heart muscle. This is a rare complication of mono; symptoms include chest pain and shortness of breath. 
  • Reye’s syndrome: This syndrome can occur as a result of aspirin use in children. To lower the risk of Reye’s syndrome, talk with your practitioner about safe analgesics for your child like acetaminophen or ibuprofen. 
  • Hemophagocytic syndrome: This rare condition can be caused by EBV and causes a child’s white blood cells to attack their other cells. This process leads to an enlarged spleen and liver, as well as nervous system problems.  

When to See a Healthcare Provider or Go to the Hospital

When your child develops the common symptoms of mono like fever, swollen lymph nodes, and fatigue, it’s time to call the healthcare provider. If you’re unsure, remember that mono symptoms usually last longer than those of a cold or the flu, so if your child is not starting to feel better a few days after symptom onset, call your pediatrician. Your practitioner’s office staff will help you determine if you should bring your child into the clinic or opt for a telehealth visit. 

Your pediatrician will start by asking about the symptoms and will then perform a physical exam, making sure to feel your child’s lymph nodes. They may recommend heading to the lab for blood tests, such as a white blood cell count or monospot test to confirm the diagnosis.

Even after your child has been diagnosed with mono, don’t hesitate to call your healthcare provider if their symptoms change or you are concerned.  Any sign of a serious complication such as difficulty breathing, confusion, or paralysis needs to be evaluated immediately.

A Word From Verywell

The long list of potential symptoms and complications of mono can be overwhelming for any parent. It’s helpful to remember that most children and teens who are diagnosed with mono experience swollen lymph nodes, fever, and fatigue, and these symptoms usually resolve on their own. Talk with your healthcare provider if you suspect that your child has become ill with mono, and stay in close contact with them if your child’s symptoms start to change. 

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8 Sources
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