Complications from mononucleosis

Most people recover from mononucleosis (mono) without any complications. But there are many possible complications of mono. These include:^{1, 2, 3}

• An enlarged spleen, which occurs in up to 50% of those with mono.
• Red spots or rash, which can develop if you are taking certain antibiotics. The rash is not an allergic reaction.
• Mild anemia, which usually goes away without treatment after 1 to 2 months.
• A lower-than-normal number of platelets in the blood (thrombocytopenia). This condition usually goes away without treatment.
• A lower-than-normal number of neutrophils, a type of white blood cell that helps fight infection. This condition usually goes away without treatment.
• Hepatitis , which can occur most often during the 2nd to 4th weeks of mono.

Other complications of mono can occur but are very rare. These include:

• A ruptured spleen. The risk of this is greatest in the second or third week of the illness. It can be the first sign of mono in a small number of people. A ruptured spleen requires immediate surgery.
• Airway obstruction and difficulty breathing, which may be caused by severely swollen tonsils that block the throat. Corticosteroids may be given to reduce swelling. In severe cases, the tonsils may need to be removed surgically (tonsillectomy).
• Brain and spinal cord problems.
• Cardiac problems, such as irregular heart rhythms, which can occur during the first 3 weeks of mono. These types of problems usually resolve on their own.
• Burkitt's lymphoma (cancer in the lymphatic system) in people of equatorial Africa.
• Cancer of the nose and throat in people of South Chinese ancestry.

While not a complication specific to mono, a serious disease known as Reye syndrome can develop if you give aspirin to your child or adolescent under the age of 20 years to treat symptoms of mono. Aspirin should not be given for the treatment of symptoms of mono. Instead, give acetaminophen (such as Tylenol) to relieve fever and pain caused by mono. Follow all instructions on the label. If you give medicine to your baby, follow your doctor’s advice about what amount to give.

Even if you develop a complication of mono, it is likely that you will recover completely.

Citations

1. Johannsen EC, et al. (2005). Epstein-Barr virus (infectious mononucleosis). In GL Mandell et al., eds., Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 6th ed., vol. 2, pp. 1801–1820. Philadelphia: Elsevier.
2. American Public Health Association (2008). Mononucleosis, infectious. In DL Heymann, ed., Control of Communicable Diseases Manual, 19th ed., pp. 428–430. Washington, DC: American Public Health Association.
3. Levin MJ, Weinberg A (2009). Infectious mononucleosis (Epstein-Barr virus). In WW Hay Jr et al., eds., Current Diagnosis and Treatment Pediatrics, 19th ed., pp. 1094–1096. New York: McGraw Hill Medical.