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.

Mononucleosis Causes 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.