What is Mononucleosis (mono)?

What is Mononucleosis (mono)?

Infectious mononucleosis, often referred to as mono, is a contagious disease most often caused by the Epstein-Barr virus (EBV). It’s very common among teenagers and young adults, particularly college students.

Mono is known to make people feel extremely tired and can take several weeks to recover from.

Signs & Symptoms of Mononucleosis (Mono)


A primary care doctor can evaluate your symptoms and determine if you have mono. The symptoms of mono typically appear four to six weeks after exposure to EBV and most often last another two to four weeks. However, some people may feel tired for longer—even up to six months or more.

Common mono symptoms may include:

  • Extreme fatigue
  • Fever
  • Swollen lymph nodes, particularly in the neck and armpits
  • Sore throat
  • Headache and body aches
  • Rash
  • Achy belly due to swollen liver and/or spleen

Most people eventually recover from these symptoms after enough rest and self-care. If your mono symptoms persist, see your primary care doctor for further treatment.

What Causes Mononucleosis (mono)?


EBV causes mono and is most often transmitted through saliva, such as through sharing of food or utensils or during kissing. This is why its nickname is the "kissing disease." EBV can also be transmitted through genital secretions and, though rarely, through blood transfusion and organ transplant.



Some people develop complications from mononucleosis, such as:

  • Enlarged spleen, which affects three out of four people with mono. If you have mono, refrain from contact sports and heavy lifting for at least four weeks after your symptoms begin to avoid rupturing your spleen.
  • Liver problems such as hepatitis (inflammation) and jaundice (yellowing of the eyes and/or skin)
  • Renal complications
  • Mild anemia (low red blood cell count)
  • Low platelet count (blood-clotting cells)
  • Abnormal white blood cells
  • Myocarditis (inflammation of the heart muscle)
  • Nervous system problems such as encephalitis, meningitis, and Guillain-Barré syndrome
  • Swollen tonsils that can make breathing difficult



There is no vaccine for mononucleosis, but you can reduce your risk of getting it by avoiding sharing food and utensils and washing your hands frequently. An infected person may be contagious with the virus in the saliva for up to six months after symptoms begin, so it’s important to take precautions to reduce the risk of transmitting the virus.

Get Care

Trust NewYork-Presbyterian for Mononucleosis (Mono) Care

If you think you might have mono, you can schedule an in-person visit or telehealth appointment with a primary care provider at a NewYork-Presbyterian campus or a NewYork-Presbyterian medical group location to receive diagnostic care and treatment.

We offer same-day appointments for those with urgent needs, convenient early, late, and weekend hours, connection with our patient portal, and referrals to NewYork-Presbyterian specialists. Most insurances are accepted. Make an appointment today.