Mononucleosis - Symptoms and Causes

Causes

Mononucleosis is primarily caused by the Epstein-Barr virus (EBV), although other viruses can cause similar symptoms. The virus spreads when saliva is shared, such as through kissing or when people share food and drinks.

Mononucleosis goes away by itself without causing lasting problems. Most grown-ups have already been exposed to the Epstein-Barr virus. Their bodies have built antibodies against it, making them immune to mononucleosis.

More Details

The virus passes easily through direct contact with saliva
Symptoms may feel uncomfortable, but are temporary
Recovery happens without long-term health issues
Once you’ve had it, you typically develop immunity
Sharing utensils and drinks can lead to transmission

Signs and Symptoms

Mononucleosis can show several common symptoms. You might feel very tired all the time. A sore throat that doesn’t improve with antibiotics is common. Many people also develop a fever.

Other symptoms include swollen lymph nodes in your neck and armpit areas. Your tonsils may become enlarged and swollen. Headaches are also frequent among people with this condition.

Some patients develop a skin rash. The spleen, an organ in your abdomen, may become soft and enlarged.

After exposure to the virus, it usually takes four to six weeks before symptoms appear. This waiting period might be shorter in young children.

Fever and sore throat usually improve in two weeks, but tiredness, swollen lymph nodes, and an enlarged spleen can last longer.

When to Visit Your Doctor

If you notice these symptoms, you might have mononucleosis. Most cases improve without special treatment.

However, you should make a doctor’s appointment if:

Your symptoms don’t get better after one to two weeks
Your symptoms become severe
You experience extreme throat pain
You have difficulty breathing

Early medical attention can help manage complications and confirm your diagnosis.

Health Complications

Spleen Enlargement

Mononucleosis often causes the spleen to grow larger than normal. In severe cases, the spleen might burst, which creates sharp pain in the upper left side of your abdomen.

This is a medical emergency that needs immediate attention and possibly surgery. If you feel this kind of sudden pain, go to the hospital right away.

Swollen Spleen

Your spleen is normally about the size of your fist. When you have mononucleosis, this organ can swell. Other health problems, like liver disease and certain cancers, can also make your spleen larger than normal.

Liver Problems

Mono can affect your liver in several ways:

Mild Inflammation: The virus may cause hepatitis, which is swelling of the liver.
Yellow Skin: Some people develop jaundice, which turns their skin and the whites of their eyes yellow.

Uncommon Complications

While less frequent, mono can sometimes lead to:

Anemia: Not enough red blood cells or hemoglobin.
Low Platelet Count: Fewer blood cells that help with clotting.
Heart Inflammation: Swelling of the heart muscle.
Brain and Nerve Issues: Including meningitis, encephalitis, and Guillain-Barré syndrome.
Blocked Airways: Very swollen tonsils that make breathing difficult.

People with weak immune systems face greater risks from the Epstein-Barr virus. This includes individuals with HIV/AIDS or those taking medication to prevent organ rejection after a transplant.

Prevention

Mononucleosis is transmitted through contact with saliva. If you have mono, avoid kissing others until several days after your fever improves.

Don’t share food, dishes, glasses, or utensils with others. This simple precaution helps reduce transmission risk.

Regular handwashing is essential to preventing the spread of the virus. The virus that causes mono can remain in your saliva for months after symptoms disappear, so continued caution is wise.

Currently, no vaccine exists that can prevent mononucleosis. Being careful about saliva contact remains the most effective prevention strategy.