Infectious Mononucleosis
Also known as: Infectious mononucleosis, unspecified · Glandular fever · Kissing disease · Mono · Mononucleosis · EBV Infections · Epstein-Barr Virus Infections
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In short
Infectious mononucleosis is a contagious disease caused by viruses, most commonly the Epstein-Barr virus, and is common among teenagers and young adults. The viruses that cause this condition are usually spread through body fluids, especially saliva, but can also be transmitted through shared food, drinks, utensils, blood transfusions, organ transplants, or sexual contact. Symptoms typically start four to six weeks after infection and can include extreme fatigue, fever, sore throat, head and body aches, swollen lymph glands, rash, or a swollen liver or spleen. Diagnosis is based on symptoms, a physical exam, and sometimes a mono test, while management involves drinking plenty of fluids, getting rest, and taking over-the-counter medications for pain and fever.
Source: MedlinePlus, National Library of Medicine.
AI-generated summary of the sources cited on this page, checked automatically against them. Not reviewed by a clinician; not medical advice.
Codes
Description
What is infectious mononucleosis (mono)?
Infectious mononucleosis (mono) is a disease caused by viruses.The most common cause is the Epstein-Barr virus (EBV). Mono is contagious, which means it can spread from person to person. It is common among teenagers and young adults, especially college students.
What causes infectious mononucleosis (mono)?
Mono can be caused by many different viruses. But it is most often caused by the Epstein-Barr virus (EBV). EBV is found all over the world. Most people get an EBV infection at some point in their lives, but only some of them will get the symptoms of mono. EBV infections often happen during childhood or when someone is a young adult. EBV infections in children usually do not cause symptoms. And when they do, it's hard to tell the difference between the symptoms of mono and the symptoms of other common childhood illnesses such as the flu. Teens and young adults who get EBV are more likely to have symptoms that are typical of mono.
EBV and the other viruses that cause mono are usually spread through body fluids, especially saliva (spit). This means that you can get it through kissing. That's why mono is sometimes called "the kissing disease." But you can also get these viruses if you share food, drinks, forks, spoons, or lip balm with someone who has mono. Other less common ways of getting an infection are through blood transfusions, organ transplants, and blood and semen during sexual contact.
What are the symptoms of infectious mononucleosis (mono)?
The symptoms of mono usually start four to six weeks after you get the infection. But they may start sooner in young children. The symptoms often develop slowly, and they may not all happen at the same time. They can include:
- Extreme fatigue
- Fever
- Sore throat
- Head and body aches
- Swollen lymph glands in your neck and armpits
- Rash
- Swollen liver, spleen, or both (these are less common symptoms)
Most people get better in two to four weeks. However, some people may feel fatigued for several more weeks. Occasionally, the symptoms can last for six months or longer.
How is infectious mononucleosis (mono) diagnosed?
Your healthcare provider may diagnose mono based on your symptoms and a physical exam. The exam will include checking to see if your lymph nodes, tonsils, liver, or spleen are swollen. In some cases, your provider might also order a mono test to confirm the diagnosis.
What are the treatments for infectious mononucleosis (mono)?
- Drinking plenty of fluids to avoid dehydration.
- Getting lots of rest.
- Taking over-the-counter medications for pain and fever. But don't give aspirin to children or teens because it may cause Reye syndrome. This syndrome is a rare, serious illness that can affect the brain and liver.
If you have severe symptoms, your provider may suggest additional treatment based on which organs in your body are affected by the mono.
Antibiotics don't treat viral infections, so they do not help with mono. Some people do get bacterial infections such as strep throat along with mono. In that case, you probably need antibiotics to treat the bacterial infection. But you should not take penicillin antibiotics like ampicillin or amoxicillin. Those antibiotics can cause a rash in people who have mono.
Mono can cause an enlarged spleen, which could rupture and cause a medical emergency. To try to protect the spleen, providers recommend avoiding intense exercise and contact sports until you fully recover (about a month).
Can infectious mononucleosis (mono) be prevented?
There is no vaccine to protect against mono. To lower your chance of getting or spreading mono:
- Don't share food, drinks, forks, spoons, or lip balm with anyone, especially if you or the other person has mono.
- Don't kiss someone if you or the other person has mono.
- Wash your hands often with soap and water.
Centers for Disease Control and Prevention
Next to it in ICD-10
- B20HIV
- B25Cytomegalovirus infection
- B26Mumps
- B30Viral conjunctivitis, unspecified
- B37Yeast Infections
- B38Valley Fever
Neighbouring codes in the classification, not a medical link.
External resources
Questions
What is the ICD-10 code for Infectious Mononucleosis?
B27 (WHO, International Classification of Diseases, 10th Revision).
What is the ICD-11 code for Infectious Mononucleosis?
1D81.Z: Infectious mononucleosis, unspecified (WHO, ICD-11 for Mortality and Morbidity Statistics).
Sources and attribution
- ICD-11 for Mortality and Morbidity Statistics, © World Health Organization, licensed under CC BY-ND 3.0 IGO.
- Source: MedlinePlus, National Library of Medicine.
- Names other than the official source titles: Anpheros translations and plain-language names, made with AI assistance and checked automatically; the source names are in English.
- ICD-10 codes and titles © World Health Organization. Source: WHO, International Classification of Diseases, 10th Revision (2019).
Anpheros Search catalog 2026.10.5, published 17 October 2026. About the data →
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