Mononucleosis (Mono)

What is mononucleosis (mono)?

Mononucleosis (mono) is a common illness caused by a virus. It can start with a fever, a sore throat, and swollen glands. And you may feel tired and weak for several weeks or longer. Mono goes away on its own, but rest and good self-care can help you feel better.

What causes mono and how does it spread?

The virus that usually causes mono—the Epstein-Barr virus (EBV)—can be spread through:

• Kissing that shares saliva. A brief kiss on the lips isn't likely to spread mono. It's spread when saliva from an infected person gets into another person's mouth.
• Mucus from the nose and throat.
• Sharing things like drinking glasses, eating utensils, and toothbrushes with a person who is infected with mono.
• Blood and semen during sexual contact, blood transfusions, and organ transplants.

Mono isn't spread by casual contact. You can live in the same house with a person who has mono and never be infected with the virus. But a person who has a weakened immune system may be at higher risk for mono.

You can pass mono to others for several weeks or months during and after the time you are first infected with mono. The virus can also become active again in your body from time to time throughout your life, and you can spread it to others. Older adults usually don't get mono, because they have been exposed during their lifetime and have immunity to the virus.

What are the symptoms?

The most common symptoms of mono include fever, sore throat, swollen lymph nodes in the neck, and feeling tired and weak. Mono can also cause pain in the upper left part of your belly if your spleen becomes enlarged. Symptoms usually start 4 to 6 weeks after you're exposed to the virus.

How is it diagnosed?

Your doctor will ask you questions about your symptoms and possible exposure to mono. Your doctor will also examine you for signs of mono. This may include looking at your throat, checking your skin, and pressing on your belly.

Blood tests to help confirm the diagnosis include:

• Mono test (EBV antibody test). A rapid mono test may be done, but it's possible for the results to be negative (false negative) in the early days of the infection.
• Complete blood count. This may be done to help rule out other infections or complications of mono.

Other tests may be done if complications of mono occur or if the mono tests are negative.

• Liver tests may be done to find out if the virus has affected your liver.
• If the mono test is negative, your doctor may test you to check if you have other infections, such as human immunodeficiency virus (HIV) or cytomegalovirus (CMV). HIV and CMV can cause an illness that's like mono.

How is mono treated?

Treatment for mono usually involves self-care measures like rest and over-the counter medicines to reduce pain and fever. In severe cases, corticosteroids may be used to reduce swelling of the throat, tonsils, or spleen.

How can you care for yourself at home?

Here are some things you can do to help your mono symptoms.

• Rest when you feel tired. Getting enough sleep will help you recover.
• Drink plenty of fluids.
• For a sore throat, suck on lozenges or gargle with salt water. To make salt water, mix 1 teaspoon of salt in 8 ounces of warm water.
• Take an over-the-counter pain medicine, such as acetaminophen (Tylenol), ibuprofen (Advil, Motrin), or naproxen (Aleve), for a sore throat or headache or to lower a fever. Read and follow all instructions on the label.
• Do not take two or more pain medicines at the same time unless the doctor told you to. Many pain medicines have acetaminophen, which is Tylenol. Too much acetaminophen (Tylenol) can be harmful.

When you have mono:

• Don't play contact sports or do strenuous activities for 4 weeks. Don't lift anything heavy. Too much activity increases the risk of damage to your spleen.
• Try not to spread the virus to others. Avoid kissing that shares saliva, and don't share dishes, glasses, eating utensils, or toothbrushes for at least a few weeks.
• If you know you have mono, don't donate blood. There's a chance of spreading the virus through blood products.