Infectious Disease Icons

Mononucleosis

Also known as mono or the “kissing disease”

Infectious mononucleosis (mono) is a condition usually caused by the Epstein-Barr virus (EBV) or, less commonly, cytomegalovirus (CMV).

Mono is sometimes called the "kissing disease" because it is spread through saliva, shared drinking cups and utensils, and close contact.

Symptoms (fever, sore throat, swollen lymph glands, enlarged tonsils, and extreme fatigue) appear approximately four to eight weeks after exposure. Infected persons "shed" the virus in their saliva and can be contagious for about  six months. The virus eventually becomes dormant but never fully goes away. It can be potentially activated again if your immune system is weakened. 

Mono is treated with rest and symptom management. Prescription drugs are rarely needed. 

Frequently Asked Questions

  • What causes mononucleosis?

    Infection by the Epstein-Barr virus (EBV) is the most common cause of mononucleosis, but other viruses can cause mono-like illnesses too, such as cytomegalovirus (CMV).

  • How do you get mononucleosis?

    Mononucleosis is primarily spread through bodily fluids, especially saliva, but also through mucus, blood, semen, and vaginal secretions. Sharing a cup, straw, or eating utensil can contribute to the spread of EBV. Blood transfusions and organ transplantations can also spread the virus. One out of 4 teens or young adults who get infected with EBV will develop mono.

  • How long does mononucleosis last?

    The incubation period for mono is four to eight weeks, which means that symptoms set in at least a month after you've been exposed to the virus. Some symptoms may only last for a few days, while others, such as fatigue, may persist for months. Mono symptoms  last for two to four weeks in most people.

  • How many times can you get mononucleosis?

    In most cases, you'll only get mono once, but as the EBV virus stays in your body for the rest of your life, it is possible that mono could make a comeback. This is rare, and generally only likely if your immune system is weakened by another infection such as HIV, an organ transplant, or pregnancy. It's also possible to get mono from a virus other than EBV, even if you already have EBV.

Key Terms

Young woman kissing boyfriend in the city
How Long Is Mononucleosis Contagious?
sick woman
Mono vs. Flu: Comparing Causes, Symptoms, and Treatments
sick teenager lying in bed
The Three Stages of Mono
Teen at doctor's office, mono diagnosis
Is Mono an STD?
Man with stomach pain and headache
Can Mono Cause Hepatitis?
a sick woman sleeping
Can You Get Mono Twice?
Teenage girl sick in bed
Symptoms of Mono in Kids
Tired woman
Can You Have Chronic Mono?
A high fever
Could It Be Mono? Symptoms to Look For
Female doctor checking teen patient's throat
Do You Have Mono? How It's Diagnosed
mono.jpg
Can Mono Be Cured?
Three generations of women cooking together in kitchenProfile of senior couple forecasting the way forward for future finance and investmentClose up of baby grabbing feetEarthquake Survivors Undertake Rehabilitation At Sichuan Provincial PeopleThe Women of Standing Rock ReservationThe Women of Standing Rock ReservationThe Women of Standing Rock ReservationNepal Plane CrashRelatives Gather at Oklahoma City Bombing MemorialNew York Farm Offers Horseriding Therapy For PTSD SufferersFor Some Returning US Troops, PTSD Is The New BattlefieldFor Some Returning US Troops, PTSD Is The New BattlefieldIraq War Vet Struggles With PTSDFort Hamilton Soldiers Attend PTSD ScreeningU.S. War Veteran And Family Cope With Post Traumatic Stress DisorderU.S. War Veteran And Family Cope With Post Traumatic Stress DisorderStormy Weather To Hit The UKMichael Jackson Court Case ContinuesMichael Jackson Court Case ContinuesWoman in nightclub throwing beverage in man's faceCrowds Flock To Notting Hill For 2011 CarnivalCrowds Flock To Notting Hill For 2011 Carnival23rd Anniversary Of 1993 WTC Bombing Commemorated At 9/11 MemorialVermont Battles With Deadly Heroin EpidemicVermont Battles With Deadly Heroin Epidemic Getty Images Friends playing poker and drinking beer and wine at table in bar : Stock Photo Embed Share Comp Save to Board Friends playing poker and drinking beer and wine at table in bar
How Long Is Mono Contagious?
Page Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Epstein-Barr Virus and Infectious Mononucleosis. About Infectious Mononucleosis. Updated September 28, 2020.

  2. Centers for Disease Control and Prevention. Epstein-Barr Laboratory Testing. Updated May 10, 2018.

  3. Kim HJ, Ko YH, Kim JE, et al. Epstein-Barr virus-associated lymphoproliferative disorders: Review and update on 2016 WHO classification. J Pathol Transl Med. 2017;51(4):352-358. doi:10.4132/jptm.2017.03.15

  4. Womack J, Jimenez M. Common questions about infectious mononucleosis. Am Fam Physician. 2015;91(6):372-376.

  5. Schechter S, Lamps L. Epstein-barr virus hepatitis: a review of clinicopathologic features and differential diagnosisArchives of Pathology & Laboratory Medicine. 2018;142(10):1191-1195. doi:10.5858/arpa.2018-0208-RA.

Additional Reading