Mononucleosis (Kissing Disease): Symptoms and Treatment

Medically Reviewed by Jabeen Begum, MD on April 30, 2024
Written by WebMD Editorial Contributors
8 min read

Mononucleosis is an infectious illness that’s usually caused by the Epstein-Barr virus (EBV). It’s also called mono or "the kissing disease." It's commonly spread through saliva. You can get the virus through kissing and things such as sharing drinks or silverware. It’s contagious, but you’re less likely to catch mono than other common illnesses such as 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 serious. if you get mono, you may not be able to take part in your normal daily activities for several weeks.

The Epstein-Barr virus causes the vast majority of mononucleosis cases. But it's possible to get it from other viruses, including:

  • Adenoviruses, a common cause of colds
  • Cytemolgovirus (CMV), another type of herpes virus
  • Hepatitis type A, B, or C
  • Herpes simplex virus
  • HIV, the virus that causes AIDS
  • Rubella, the virus that causes measles

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. In the U.S., about 85%-90% of adults carry the virus by the time they’re 40.

EBV is part of the herpes virus family, but it's not the same as the virus that causes oral or genital herpes.

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 such as a fork or spoon, the virus probably stays contagious as long as the object remains 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.

Is mono an STD?

Because the virus that causes mono can be spread through all types of body fluids, it can be a sexually transmitted disease (STD). But it's most often spread by saliva.

How long is mono contagious?

You may be contagious as soon as you get infected with the virus before you even know you have it. It might take a month or two for symptoms to appear. Doctors know you're contagious during the time you have symptoms. It's not clear how long you stay contagious after symptoms pass, but doctors think it may be several months.

Can you get mono more than once?

Once you have EBV, the virus stays in your body for life. It can sometimes reactivate and you can spread the virus to others. But you most likely won't have mono symptoms again. But if you get mono that's caused by a different virus or if you have a weakened immune system, symptoms may come back.

Mononucleosis can cause different symptoms in different people. Common symptoms include:

Less commonly, you could have:

  • A cough
  • Chest pain
  • Shortness of breath
  • Headache
  • Nosebleeds
  • A fast heartbeat
  • A stiff neck
  • Hives
  • Jaundice, in which your skin and the whites of your eyes have a yellow tint

Some people have either no symptoms or very mild ones that they don’t notice.

Most people who get mono feel better in about 2-4 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.

Mono rash

You could develop a blotchy, reddish, or pinkish rash that looks like measles, especially if you've taken antibiotics for a throat infection. The rash could show up on your face and/or body. It may or may not itch.

Rarely, mono can cause hives. These are itchy, reddish, or flesh-colored bumps on your skin that tend to come and go quickly.

After you've been exposed to the virus that causes mononucleosis, it may take a month or two for symptoms to develop. This is known as the incubation period.

The incubation period is followed by the prodromal stage when the virus is spreading in your body. It may last about 5-14 days. You may have mild symptoms such as:

  • Tiredness
  • Headache
  • Sore throat
  • Overall achiness

The acute stage, in which you're actively sick, can last 6 days or longer. Your symptoms become more noticeable. Your sore throat gets worse, your tonsils swell up, you feel feverish, and your lymph nodes may hurt.

After the worst symptoms pass, you enter the convalescent or recovery stage. You might have fatigue and weakness for up to 6 months.

How long does mono take to show up?

Some people never get any symptoms after being exposed to the virus that causes mono. In those who do, it most often takes 4-6 weeks for symptoms to show up.

Your doctor can usually diagnose mononucleosis based on your symptoms. They might also check for swelling in your tonsils, lymph nodes, liver, or spleen.

Mono tests

Doctors can confirm a mono diagnosis with blood tests, including:

Complete blood count (CBC). This test lets your doctor look at your white blood cells to see whether any of them are unusual or whether you have more than usual.

Antibody tests. This test can show your doctor whether your immune system has created certain proteins in response to EBV.

Mono vs. strep

Mononucleosis and strep throat have some of the same symptoms, such as a sore throat, fever, and swollen lymph nodes. But while mono is usually caused by a virus, strep throat is caused by streptococcus bacteria. You can also have strep throat at the same time as mono.

Complications from mononucleosis can be serious. They may include:

Swollen tonsils. They might narrow your airway, making it harder to swallow or breathe through your mouth. 

Enlarged spleen. If it becomes serious, 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 such as 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, such as acetaminophen or nonsteroidal anti-inflammatory drugs, for fever and pain
  • Corticosteroid medication for swelling in your throat
  • Gargling with salt water (1/4 teaspoon of salt in an 8-ounce cup of warm water) to ease throat pain

Is mono curable?

Treatment can help relieve symptoms, but there's no cure for mono. Rest can help you recover more quickly.

How long does mono last?

How long mononucleosis symptoms last varies from person to person. Most improve in 2 weeks to 1 month. But some symptoms, such as fatigue and weakness, can linger for months. The virus that causes mono lives in your body for the rest of your life.

Does mono go away on its own?

Symptoms usually go away on their own within a few weeks.

 

It can take a while to completely recover from mono. The best way to speed up your healing is to rest as much as you can.

You probably won’t need to quarantine. But you do need to stay home from school or work until your symptoms ease. You’ll likely need help from your friends or family as you get better.

Your doctor will likely tell you to wait about a month before you do strenuous activities such as sports, weightlifting, or moving heavy objects. These things increase your risk of rupturing your spleen, which is a medical emergency. Mono can cause your spleen, an organ in your belly area, to become enlarged.

It's also important to avoid alcohol when you have mono. Mono can affect your liver, and drinking alcohol on top of it could lead to liver damage.

You'll probably return to your usual routines slowly and gradually. Ask your doctor about when it's safe to do so.

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. Avoid contact with people who are sick and try not to share things such as drinks, silverware, or toothbrushes with others.

 

Mononucleosis, also called the kissing disease, is a contagious disease most often caused by the Epstein-Barr virus (EBV). It’s usually not serious but can take some time to recover. While there's no cure, lots of rest, plenty of liquids, and over-the-counter pain relievers can help you feel better.

How contagious is mononucleosis?

Mono is most often passed through saliva. You might get it when you kiss or share a drink, eating utensils, or toothbrush with another person. Casual contact doesn't spread it, and most people already have the virus in their bodies. So, there's no need to quarantine while you have mono. Mononucleosis isn't as contagious as the cold virus, for example.