What Is Mononucleosis?
Mononucleosis is an infectious illness that’s usually caused by the Epstein-Barr virus (EBV). It’s also called mono or “the kissing disease.” You can get the virus through kissing as well as things like sharing drinks or silverware. It’s contagious, but you’re less likely to catch mono than other common illnesses like a cold.
Mono isn’t usually a serious illness, but you can have complications that make it more dangerous. The symptoms of mono can range from mild to severe. You may not be able to take part in your normal daily activities for several weeks.
Many people are exposed to EBV as kids. But that doesn’t always mean you’ll get mono. You can carry the virus in your body for your entire life without ever having symptoms of mono.
EBV is part of the herpes virus family. Most people are exposed to it at some point in their lives. In the U.S., about 85% to 90% of adults carry the virus by the time they’re 40.
How Do You Get Mono?
EBV spreads through bodily fluids, usually saliva, which is why you can get it through kissing. You can also get it if you share food, drinks, or silverware with a person who has it or, rarely, if an infected person coughs or sneezes near you. If someone who has mono uses an object like a fork or spoon, the virus is probably still contagious as long as the object is still moist.
EBV can be spread through blood and semen. It’s unusual, but you can get mono from medical procedures such as blood transfusions and organ transplants, or through sexual contact.
Mono can cause different symptoms in different people. If you get EBV, you may start to have symptoms of mono within about 4 to 7 weeks. Common symptoms include:
- Sore throat
- Swollen lymph nodes
- Sore muscles
- Loss of appetite
Some people have no symptoms or ones that are so mild, they don’t notice them.
Most people who get mono feel better in about 2 to 4 weeks. Sometimes, fatigue can last several weeks after that. In some cases, it can take 6 months or longer for the symptoms to go away.
Your doctor can usually diagnose mono based on your symptoms. They might also check for swelling in your tonsils, lymph nodes, and liver or spleen.
They can confirm a mono diagnosis with blood tests including:
- Complete blood count (CBC). Your doctor will look at your white blood cells, including whether any of them are unusual or whether you have more than usual.
- Antibody tests. Your doctor will look for proteins that your immune system creates in response to EBV.
Complications from mono can be serious. They might include:
- Swollen tonsils. They might narrow your airway, making it harder to swallow or breathe through your mouth.
- Enlarged spleen. If it becomes severe, your spleen can burst. This causes a sudden sharp pain on the left side of your upper belly. If you have pain like this, it’s an emergency. Get medical care right away. You may need surgery.
- Liver problems. You might have hepatitis or jaundice.
- Blood problems. Your body might destroy too many of your red blood cells (hemolytic anemia). Or your blood might not have enough platelets (thrombocytopenia).
- Heart problems. Your heart muscle might become inflamed (myocarditis), or you might have an uneven heartbeat.
- Nervous system problems. This can include seizures, brain inflammation (encephalitis), or inflammation of the tissues covering your brain (meningitis).
You’re more likely to have serious complications from mono if your immune system is weakened because of an illness like HIV or AIDS, or because you take certain medications.
No medications treat mono. Antibiotics and antivirals don’t work on EBV. Things that may help you feel better include:
- Lots of rest
- Lots of fluids
- Over-the-counter pain relievers, like acetaminophen or nonsteroidal anti-inflammatory drugs, for fever and pain
- Corticosteroid medication for swelling in your throat
There’s no vaccine to prevent mono. EBV can stay in your saliva for months after you’re infected, so even if you don’t have symptoms or feel sick, you may be able to spread it.
To lower your chances of getting mono, wash your hands often and try not to share things like drinks, silverware, or toothbrushes with other people.