Infectious mononucleosis, often called “mono,” is a flu-like illness that is common in teens and young adults. The board-certified, fellowship-trained pediatric infectious disease specialists with Norton Children’s Infectious Diseases have the experience and skills to treat mono in children.

How Long Does Mono Last?

Symptoms of mono in children usually last about two to four weeks, but fatigue may continue for weeks or even months after other symptoms improve. The duration varies depending on the child’s age, the severity of the illness and the recovery process.

• After exposure: Symptoms typically appear four to six weeks after infection with the Epstein-Barr virus (EBV), the most common cause of mono.
• First two to four weeks of illness: Fever, sore throat, swollen lymph nodes and other symptoms usually improve gradually.
• Following weeks or months: Fatigue and reduced stamina may continue after other symptoms resolve. Children may need additional rest before returning to their usual activities.
• Younger children: Symptoms may be mild or absent, making mono harder to recognize.
• Teenagers: Teens are more likely to experience classic mono symptoms, including extreme fatigue, fever, sore throat and swollen lymph nodes.

Children recovering from mono should avoid sports, heavy lifting and rough play until their health care provider clears them. Mono can cause an enlarged spleen, which can rupture following an injury.

What Is Mono?

Mono is a viral illness that is very contagious and spreads through saliva. The most common cause of mono is the Epstein-Barr virus (EBV). Other viruses, including cytomegalovirus (CMV), can cause mono-like illnesses.

How Do You Get Mono?

Mono often is spread through contact with infected saliva by kissing, coughing, sneezing or sharing drinking glasses or food utensils. Most kids are exposed to EBV at some point in their childhoods and may experience mild symptoms or none at all. Children exposed to EBV have a 50% chance of developing symptoms of mono.

Symptoms of Mono in Kids

Children usually show signs of mono one to two months after exposure. Symptoms of infectious mononucleosis can vary, but common symptoms include:

• Extreme fatigue (feeling very tired)
• Fever
• Headache and body aches
• Sore throat
• Swollen lymph nodes in the neck, armpits and groin
• Swollen spleen or liver

Less common symptoms can include puffy eyes, nausea, sensitivity to light, chest pain and trouble breathing. Younger children may have milder symptoms, such as slight fever, feeling tired and poor appetite.

Symptoms of mono in kids can last for about two to four weeks, but the fatigue may last for weeks after symptoms end.

When Should You Seek Medical Care?

Seek emergency medical care if your child has sudden, severe pain in the upper left side of the abdomen or left shoulder, which may indicate a ruptured spleen. Difficulty breathing or swallowing also requires urgent medical attention.

Contact your child’s health care provider if symptoms worsen, fever persists, your child has difficulty drinking fluids or fatigue significantly interferes with daily activities.

What Causes Mono?

Mono is most commonly caused by the Epstein-Barr virus (EBV), a member of the herpesvirus family. EBV spreads primarily through saliva. Many people become infected during childhood without developing noticeable symptoms.

Less commonly, mono-like symptoms can be caused by other infections, including:

• Cytomegalovirus (CMV): A virus that can cause symptoms similar to EBV-related mono.
• Other viral infections: Some viral illnesses can cause fever, fatigue, swollen lymph nodes and a sore throat that resemble mono.

A health care provider can evaluate your child’s symptoms and determine whether testing is needed to identify the cause.

Mono Treatment

There is no cure for mono. Antibiotics do not treat the condition and will not help a child unless they are experiencing another infection caused by bacteria. Mono symptoms can go away on their own after a few weeks. Bed rest, drinking fluids and eating healthfully can help a child with mono. Other treatments can include:

• Acetaminophen or ibuprofen to help with body aches or fever. Do not give aspirin, as it may lead to Reye’s syndrome, a serious illness.
• Steroid medicines to help with enlarged tonsils or lymph nodes causing breathing difficulty.
• Rest from sports, heavy lifting or rough play until the child’s health care provider clears them for activity.

Why Choose Norton Children’s Infectious Diseases?

• Norton Children’s Infectious Diseases specializes in the care of children from birth through adolescence.
• With seven infectious diseases specialists and one nurse practitioner on staff, your child can be seen quickly, especially for urgent needs.
• Members of our team are nationally recognized and have held or serve in leadership positions related to infectious diseases.
• Our team provides inpatient consultation services at Norton Children’s Hospital and Norton Women’s & Children’s Hospital, as well as telemedicine services throughout Kentucky. Our physicians also treat patients at UofL Hospital.
• Keep up with your child’s lab results, communicate with your provider and schedule appointments through Norton MyChart.

Frequently Asked Questions About Mono

What Are the Symptoms of Mono?

Common symptoms of mono include extreme fatigue, fever, a sore throat, swollen lymph nodes in the neck or armpits, headaches and muscle aches. Some children also develop swollen tonsils or an enlarged spleen or liver. Symptoms can vary by age, and younger children may experience only mild symptoms or no noticeable illness.

How Do You Get Mono?

Mono is most commonly spread through saliva from someone infected with the Epstein-Barr virus. Kissing, sharing drinks, or using the same eating utensils or toothbrushes can transmit the virus. Children also may be exposed through other contact with infected saliva. Symptoms often take four to six weeks to appear after infection.

How Contagious Is Mono?

Mono spreads primarily through saliva. An infected person may spread the virus for weeks or months, including after symptoms improve. The virus also can remain in the body and reactivate later. Avoiding kissing and sharing drinks, utensils and toothbrushes can reduce exposure, but preventing transmission completely can be difficult.

What Are the Symptoms of Mononucleosis in a Teenager?

Teenagers with mononucleosis commonly experience extreme fatigue, fever, a sore throat and swollen lymph nodes, particularly in the neck. Headaches, muscle aches and swollen tonsils also may occur. Some teens develop an enlarged spleen or liver. Symptoms often last two to four weeks, while fatigue may persist longer and require additional recovery time.