Infectious Mononucleosis (EBV)
What is Infectious Mononucleosis (EBV)?
Infectious mononucleosis is a viral illness caused by the Epstein-Barr virus, often called EBV. Most people know it as mono or the kissing disease. EBV spreads through saliva, which is why it often affects teenagers and young adults.
The virus infects your white blood cells, especially lymphocytes. Your immune system responds by creating special lymphocytes called atypical lymphocytes or Downey cells. These distinctive cells help doctors identify mono in blood tests. Most people recover fully within a few weeks to months, though fatigue can linger.
About 90% of adults worldwide have been infected with EBV at some point in their lives. Many people get it during childhood and have mild symptoms or none at all. When infection happens in adolescence or adulthood, symptoms tend to be more noticeable and intense.
Symptoms
- Extreme fatigue that lasts for weeks or months
- Severe sore throat that may look like strep throat
- Swollen lymph nodes in the neck and armpits
- Fever, usually between 101 and 104 degrees
- Swollen tonsils with white patches
- Enlarged spleen or liver
- Skin rash, especially after taking certain antibiotics
- Headache and body aches
- Loss of appetite
- Night sweats
Young children infected with EBV often have very mild symptoms that can be mistaken for a common cold. Some people carry the virus and never show any symptoms at all.
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Causes and risk factors
Infectious mononucleosis is caused by the Epstein-Barr virus, which spreads through saliva and other body fluids. You can get it from kissing, sharing drinks or utensils, or being near someone who coughs or sneezes. The virus has an incubation period of 4 to 6 weeks, meaning symptoms appear long after exposure. This makes it hard to know exactly when or how you got infected.
Teenagers and young adults ages 15 to 25 have the highest risk of developing symptomatic mono. People with weakened immune systems may experience more severe symptoms or complications. Close living quarters like college dorms and military barracks increase transmission risk. Once infected, the virus stays in your body for life but usually remains inactive after the initial illness.
How it's diagnosed
Doctors diagnose infectious mononucleosis through a combination of physical exam findings and blood tests. A complete blood count, or CBC, reveals elevated lymphocytes and the presence of atypical lymphocytes that are characteristic of EBV infection. These distinctive white blood cells help confirm the diagnosis when combined with your symptoms.
Rite Aid offers testing that includes lymphocyte counts through our flagship blood panel at Quest Diagnostics locations nationwide. Your doctor may also order a heterophile antibody test, also called a monospot test, which detects antibodies your body makes in response to EBV. Testing is especially helpful because mono symptoms can look like strep throat or other infections that need different treatment.
Treatment options
- Get plenty of rest and allow your body time to heal, usually 2 to 4 weeks
- Stay hydrated by drinking water, herbal tea, and broth throughout the day
- Take over-the-counter pain relievers like acetaminophen or ibuprofen for fever and pain
- Gargle with salt water to soothe your sore throat
- Avoid contact sports and heavy lifting for at least 4 weeks to prevent spleen rupture
- Eat nutrient-dense foods when your appetite returns to support immune function
- Avoid alcohol while your liver recovers
- Do not take ampicillin or amoxicillin, as these often cause a rash in people with mono
There is no antiviral medication that treats EBV directly. Treatment focuses on managing symptoms while your immune system fights the infection. See a doctor if you have severe abdominal pain, difficulty breathing, or symptoms that worsen instead of improve after a few weeks.
Concerned about Infectious Mononucleosis (EBV)? Get tested at Rite Aid.
- Simple blood draw at your nearest lab
- Results in days, not weeks
- Share results with your doctor
Frequently asked questions
Most people feel better within 2 to 4 weeks, though fatigue can last several months. The sore throat and fever usually improve within the first 2 weeks. Your spleen may stay enlarged for several weeks, which is why you need to avoid contact sports during recovery. Some people experience lingering tiredness for up to 6 months after the initial infection.
Most people only get symptomatic mono once in their lifetime. After your first infection, EBV stays in your body but becomes inactive. Your immune system keeps the virus under control so you do not develop symptoms again. People with severely weakened immune systems may experience reactivation, but this is rare.
Yes, mono is contagious and spreads through saliva and other body fluids. You can spread the virus from the time you get infected until several weeks after symptoms disappear. The virus can remain in your saliva for months after recovery. Avoid kissing, sharing drinks or utensils, and close contact with others while you are sick.
A complete blood count checks for elevated lymphocytes and atypical lymphocytes that are typical of EBV infection. These distinctive white blood cells appear in your bloodstream as your immune system fights the virus. Doctors may also order a heterophile antibody test to confirm the diagnosis. Rite Aid offers lymphocyte testing through our flagship panel at Quest Diagnostics locations.
Infectious mononucleosis earned this nickname because it commonly spreads through saliva during kissing. The virus passes easily from person to person through close contact. However, you can also get mono from sharing drinks, food, or utensils with an infected person. Any exchange of saliva can transmit the Epstein-Barr virus.
See a doctor if you have a severe sore throat lasting more than a few days, extreme fatigue, or swollen glands. Get immediate medical care if you experience sharp pain in the upper left side of your abdomen, which could signal a ruptured spleen. Also seek help if you have difficulty breathing, severe headache, or symptoms that get worse instead of better after 2 weeks.
Most people recover from mono without complications, but some develop serious problems. An enlarged spleen can rupture if injured, which is a medical emergency. Liver inflammation, anemia, and low platelet counts can occur in some cases. Rarely, mono causes neurological complications like meningitis or Guillain-Barré syndrome. Very rarely, EBV infection is linked to certain cancers years later.
Avoid kissing or sharing drinks, food, or utensils with people who have mono. Wash your hands frequently, especially after being around sick people. Do not share lip balm, toothbrushes, or eating utensils with others. There is currently no vaccine to prevent EBV infection, so avoiding exposure is your best defense.
Ampicillin and amoxicillin often cause a distinctive red rash in people with infectious mononucleosis. This happens because of how EBV affects your immune system, not because you are allergic to these antibiotics. The rash usually appears within a few days of starting the medication. If you develop a rash while taking antibiotics for what you thought was strep throat, get tested for mono.
Focus on nutrient-dense foods that support immune function during recovery. Eat plenty of fruits and vegetables rich in vitamins C and A. Include protein from fish, chicken, eggs, and legumes to help repair tissues. Drink bone broth for minerals and hydration. Avoid alcohol completely while your liver heals, and limit processed foods and sugar that can stress your immune system.