What is Mononucleosis?

Mononucleosis—or mono—is an infectious disease most often caused by the Epstein-Barr virus (EBV). Because it’s easily transmitted through saliva, mono is also called the “kissing disease.” In addition to kissing, mono can be transmitted by sharing drinks or utensils.

The mono virus occurs most often in adolescents and young adults. While it’s not a serious illness, there can be serious complications that are caused by mono, including an enlarged spleen or swollen liver. However, in the majority of cases, severe fatigue is the most extreme symptom, interrupting normal activities for several weeks. 


The following are the most common mono symptoms:

  • Extreme fatigue
  • A sore throat that may mimic strep throat, but doesn’t improve with antibiotic treatment
  • Swollen tonsils
  • Swollen lymph nodes, especially in the neck and armpits
  • Skin rash
  • Headache
  • A soft and swollen spleen


Your doctor will take several factors into account before making a mono diagnosis. And because mono symptoms can mimic those of other more serious viruses, a battery of tests may need to be run before a diagnosis is made. 

For instance, mono symptoms are similar to those of Hepatitis A, so testing will need to be done to eliminate it as the cause of your symptoms. Here’s what you can expect from a mono test:

  • An initial exam: During this exam, your doctor will ask you how long you’ve had symptoms. They’ll take into account your age, as mono usually affects people between 15 and 25. They’ll also check the glands in your neck, armpits, and groin.
  • A complete blood count: This test will help determine the severity of your illness by monitoring various blood cell counts and looking for signs of infection.
  • A white blood cell count: A high white blood cell count can indicate that your body is trying to defend itself from a mono infection.
  • The monospot test: Also called the heterophile test, this blood test looks for the heterophile antibodies your body would likely produce if infected with EBV.
  • EBV antibody test: This test can detect mono in the first week you have symptoms, but it takes longer to get the results than other tests. It looks for the antibodies for EBV.

Causes and Prevention

Although it spreads easily, you’re more likely to contract a cold than contract mono. Often times, people carry the virus without ever developing symptoms strong enough to notice. Here are some of the ways that the virus spreads:

  • Through kissing
  • By sharing food, drinks, or utensils
  • In some instances through coughing or sneezing
  • Through blood or semen during sexual contact
  • Through blood transfusions
  • Through organ transplants

While mono can be caused by other viruses, the Epstein-Barr virus (EBV) is the most common cause of mono. Many people develop EBV infections as young children, but only show very mild symptoms, if any—and a child that develops EBV will likely be immune to mono.

Mono is hard to prevent, but there are some precautions you can take. If you are infected or suspect someone is infected, don’t kiss or share food or drink or utensils with that person.


Because there is no vaccine or cure, mononucleosis treatment focuses on alleviating symptoms. The mono virus can’t be treated like a bacterial infection—and the virus doesn’t respond to antiviral medications. Here is what you can expect to help aid your recovery if you contract mono:

  • Plenty of rest: Fatigue is a major condition with mono and sleep will help your body fight infection.
  • Plenty of fluids: Fight off dehydration with an increased intake of liquids
  • Over-the-counter pain relievers: Rely on ibuprofen and acetaminophen to relieve fever, inflammation and head and muscle aches
  • Throat lozenges: Get relief for throat pain with these, or gargle with salt water
  • Avoiding physical activity: An enlarged spleen can be part of mono, and physical activity can increase the risk of rupture. Avoid physical activity while you’re ill and for up to four weeks after your recovery.


While mono symptoms are typically managed without medical intervention, there are some mono complications that may require you to see your doctor immediately. Know these potential issues and use the list below as your guide.

  • Enlargement of the spleen: This may lead to the spleen rupturing, which causes a sudden, sharp pain in the upper left side of the abdomen. Immediate medical attention is required, as you may need surgery.
  • Hepatitis: This inflammation of the liver can occur with mono.
  • Jaundice: This is another liver issue that can occur, and results in yellowing of the skin and eyes.
  • Anemia: Anemia is a decrease in red blood cells and hemoglobin.
  • Thrombocytopenia: Low counts of platelets, which affect the blood’s ability to clot, cause this condition.
  • Heart problems: Myocarditis, which is an inflammation of the heart, can occur.
  • Nervous system issues: Meningitis, encephalitis, and Guillain-Barre syndrome can all occur with mono.
  • Swollen tonsils: Enlarged tonsils can cause difficulty breathing.

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