Health Topic

Infectious Mononucleosis

Infectious mononucleosis (mono), or "the kissing disease," is a viral infection. It is often caused by the Epstein-Barr virus (EBV), which can spread in saliva.

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Also called: Glandular fever · Kissing disease · Mono · Mononucleosis

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Infectious Mononucleosis

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.

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.

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.

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.

  • 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).

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

It sits within Infections and Immune System.

The lead U.S. institute for this subject is the National Institute of Allergy and Infectious Diseases.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Infectious Mononucleosis

25 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

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Diagnosis and Tests

Related Issues

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Infectious Mononucleosis. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Infectious Mononucleosis, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.