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Does Mono have complications?

Sometimes. The main serious concern with mono is that the spleen will enlarge and even rupture (tear open). The spleen is like a large gland. It's located in the upper part of your abdomen on the left side. It has functions that relate to your blood.

Most people who have infectious mononucleosis recover completely with no problem, but sometimes complications from EBV infection can occur.  These can include blood disorders leading to lowered numbers of red and white blood cells because of decreased production of these cells by the bone marrow, or destruction of red blood cells (hemolytic anemia).

Other rare complications of EBV infection include rupture of the spleen, inflammation of the heart muscle (myocarditis), involvement of the central nervous system (aseptic meningitis and encephalitis), and a nervous system disorder known as Guillain-Barré syndrome that can paralyze muscles.

Although a ruptured spleen is rare in people with mono, it's wise to be aware of the signs and call your doctor right away if you notice any of them. Signs of a ruptured spleen include pain in the left upper part of your abdomen (under the left chest), feeling lightheaded, feeling like your heart is beating fast and hard, bleeding more easily than usual and having trouble breathing.

The Epstein-Barr virus can cause much more serious illness in people who have impaired immune systems, such as people with AIDS or people taking drugs to suppress immunity following an organ transplant.

Mononucleosis runs its course and typically goes away in 2-4 weeks. More than 95% of people recover normally. Complications are uncommon but may be life threatening. Death from mononucleosis is very rare, and most often results if the spleen ruptures or if the airway is blocked or if there are neurological complications.

  • The spleen (which is an organ that is actually a big lymph node) ruptures in about 0.5% of people with mononucleosis. Approximately 90% of these are male. Rupture usually occurs during the second or third week of the illness. The person is feeling better and resumes strenuous activities and thus endangers himself or herself. In the event of this complication, doctors may surgically remove the spleen.

  • Airway obstruction occurs in 1 out of every 100 to 1,000 cases of mononucleosis. It may occur at any age but is more common in young children. Corticosteroids may be used to treat this complication.

  • Autoimmune hemolytic anemia (the body destroys the red blood cells) occurs in 1-3% of people with mononucleosis. It usually becomes clinically apparent during the second or third week of illness. Corticosteroids may be used to treat this complication.

  • Thrombocytopenia, which is a decrease in platelets in the blood, has been noted in up to 50% of people with mononucleosis. It is usually mild and not life threatening. If severe, corticosteroids may be used to treat this complication.

  • Hepatitis caused by the Epstein-Barr virus occurs in 80-90% of people with mononucleosis. It is usually mild and goes away by itself.

  • Neurological complications rarely may occur. These might include seizures, Guillain-Barré syndrome, Bell palsy, transverse myelitis, encephalitis, meningitis, and cranial nerve palsies. Corticosteroids may be used to treat these complications.

  • Complications involving the heart, lungs, or kidneys rarely occur.

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Date of Last Update: 07/27/12