Infectious mononucleosis (mono) is often called the kissing disease. The virus that causes mono (Epstein-Barr virus) is spread through saliva. You can get it through kissing, but you can also be exposed by sharing a glass or food utensils with someone who has mono. However, mononucleosis isn't as contagious as some infections, such as the common cold.

You're most likely to get mononucleosis with all the signs and symptoms if you're a teen or young adult. Young children usually have few symptoms, and the infection often goes undiagnosed.

If you have mononucleosis, it's important to be careful of certain complications such as an enlarged spleen. Rest and enough fluids are keys to recovery.

Signs and symptoms of mononucleosis may include:

• Fatigue
• Sore throat, perhaps misdiagnosed as strep throat, that doesn't get better after treatment with antibiotics
• Fever
• Swollen lymph nodes in your neck and armpits
• Swollen tonsils
• Headache
• Skin rash
• Soft, swollen spleen

The virus has an incubation period of about four to six weeks, although in young children this period may be shorter. The incubation period refers to how long before your symptoms appear after being exposed to the virus. Signs and symptoms such as a fever and sore throat usually lessen within a couple of weeks. But fatigue, enlarged lymph nodes and a swollen spleen may last for a few weeks longer.

When to see your doctor

If you've been experiencing the above symptoms, you may have mononucleosis.

If your symptoms don't get better on their own in a week or two, see your doctor.

The most common cause of mononucleosis is the Epstein-Barr virus, but other viruses also can cause similar symptoms. This virus is spread through saliva, and you may catch it from kissing or from sharing food or drinks.

Although the symptoms of mononucleosis are uncomfortable, the infection resolves on its own without long-term effects. Most adults have been exposed to the Epstein-Barr virus and have built up antibodies. This means they're immune and won't get mononucleosis.

Complications of mononucleosis can sometimes be serious.

Enlargement of the spleen

Mononucleosis may cause enlargement of the spleen. In extreme cases, your spleen may rupture, causing sharp, sudden pain in the left side of your upper abdomen. If such pain occurs, seek medical attention immediately — you may need surgery.

Liver issues

Problems with your liver also may occur:

• Hepatitis. You may experience mild liver inflammation (hepatitis).
• Jaundice. A yellowing of your skin and the whites of your eyes (jaundice) also occurs occasionally.

Less common complications

Mononucleosis can also result in less common complications, including:

• Anemia — a decrease in red blood cells and in hemoglobin, an iron-rich protein in red blood cells
• Thrombocytopenia — a low count of platelets, which are blood cells involved in clotting
• Heart problems — an inflammation of the heart muscle (myocarditis)
• Complications involving the nervous system — meningitis, encephalitis and Guillain-Barre syndrome
• Swollen tonsils — which can block breathing

The Epstein-Barr virus can cause much more serious illness in people who have impaired immune systems. People with weakened immune systems may include people with HIV/AIDS or people taking drugs to suppress immunity after an organ transplant.

Mononucleosis is spread through saliva. If you're infected, you can help prevent spreading the virus to others by not kissing them and by not sharing food, dishes, glasses and utensils until several days after your fever has improved — and even longer, if possible. And remember to wash your hands regularly to prevent spread of the virus.

The Epstein-Barr virus may persist in your saliva for months after the infection. No vaccine exists to prevent mononucleosis.

Physical exam

Your doctor may suspect mononucleosis based on your signs and symptoms, how long they've lasted, and a physical exam. He or she will look for signs such as swollen lymph nodes, tonsils, liver or spleen, and consider how these signs relate to the symptoms you describe.

Blood tests

• Antibody tests. If there's a need for additional confirmation, a monospot test may be done to check your blood for antibodies to the Epstein-Barr virus. This screening test gives results within a day. But it may not detect the infection during the first week of the illness. A different antibody test requires a longer result time, but can detect the disease even within the first week of symptoms.
• White blood cell count. Your doctor may use other blood tests to look for an elevated number of white blood cells (lymphocytes) or abnormal-looking lymphocytes. These blood tests won't confirm mononucleosis, but they may suggest it as a possibility.

There's no specific therapy available to treat infectious mononucleosis. Antibiotics don't work against viral infections such as mono. Treatment mainly involves taking care of yourself, such as getting enough rest, eating a healthy diet and drinking plenty of fluids. You may take over-the-counter pain relievers to treat a fever or sore throat.

Medications

• Treating secondary infections and other complications. A streptococcal (strep) infection sometimes goes along with the sore throat of mononucleosis. You may also develop a sinus infection or an infection of your tonsils (tonsillitis). If so, you may need treatment with antibiotics for these accompanying bacterial infections.

  Severe narrowing of your airway may be treated with corticosteroids.

• Risk of rash with some medications. Amoxicillin and other antibiotics, including those made from penicillin, aren't recommended for people with mononucleosis. In fact, some people with mononucleosis who take one of these drugs may develop a rash. The rash doesn't necessarily mean that they're allergic to the antibiotic, however. If needed, other antibiotics that are less likely to cause a rash are available to treat infections that may go along with mononucleosis.

Besides getting plenty of rest, these steps can help relieve symptoms of mononucleosis:

• Drink plenty of water and fruit juices. Fluids help relieve a fever and sore throat and prevent dehydration.

• Take an over-the-counter pain reliever. Use pain relievers such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin IB, others) as needed. These medicines have no antiviral properties. Take them only to relieve pain or a fever.

  Use caution when giving aspirin to children or teenagers. Though aspirin is approved for use in children older than age 3, children and teenagers recovering from chickenpox or flu-like symptoms should never take aspirin. This is because aspirin has been linked to Reye's syndrome, a rare but potentially life-threatening condition, in such children.

• Gargle with salt water. Do this several times a day to relieve a sore throat. Mix 1/4 teaspoon (1.5 grams) of salt in 8 ounces (237 milliliters) of warm water.

Wait to return to sports and some other activities

Most signs and symptoms of mononucleosis ease within a few weeks, but it may be two to three months before you feel completely normal. The more rest you get, the sooner you should recover. Returning to your usual schedule too soon can increase the risk of a relapse.

To help you avoid the risk of rupturing your spleen, your doctor may suggest that you wait about one month before returning to vigorous activities, heavy lifting, roughhousing or contact sports. Rupture of the spleen results in severe bleeding and is a medical emergency.

Ask your doctor about when it's safe for you to resume your normal level of activity. Your doctor may recommend a gradual exercise program to help you rebuild your strength as you recover.

Mononucleosis can last weeks, keeping you at home as you recover. Be patient with your body as it fights the infection.

For young people, having mononucleosis will mean some missed activities — classes, team practices and parties. Without a doubt, you'll need to take it easy for a while. Students need to let their schools know they are recovering from mononucleosis and may need special considerations to keep up with their work.

If you have mononucleosis, you don't necessarily need to be quarantined. Many people are already immune to the Epstein-Barr virus because of exposure as children. But plan on staying home from school and other activities until you're feeling better.

Seek the help of friends and family as you recover from mononucleosis. College students should also contact the campus student health center staff for assistance or treatment, if necessary.

If you suspect you have mononucleosis, see your family doctor. Here's some information to help you get ready for your appointment and know what to expect from your doctor.

What you can do

• Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
• Write down key personal information, noting any major stresses, recent life changes, your daily routine — including sleep habits — or exposure to anyone with mononucleosis.
• Make a list of all medications, vitamins and supplements you're taking.
• Write down questions to ask your doctor.

Preparing a list of questions will help you make the most of your time with your doctor. For mononucleosis, some basic questions to ask your doctor include:

• What are the likeliest causes of my symptoms or condition?
• Other than the most likely cause, what are other possible causes for my symptoms or condition?
• What tests do I need?
• I have other health conditions. How can I best manage them together?
• Are there restrictions I need to follow?
• Do I need to stay home from work or school? How long should I stay home?
• When can I return to strenuous activities and contact sports?
• Are there any medications I need to avoid?
• Are there brochures or other printed material that I can take with me? What websites do you recommend?

Don't hesitate to ask any other questions.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, including:

• When did you develop symptoms?
• Have you been exposed to anyone with mononucleosis?
• Have your symptoms been continuous or occasional?
• How severe are your symptoms?
• What, if anything, seems to improve your symptoms?
• What, if anything, appears to worsen your symptoms?