Mononucleosis Complications

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

• An enlarged Reference spleen Opens New Window, which occurs in up to 50 out of 100 people who have mono.
• Red spots or rash, which can develop if you are taking certain antibiotics. The rash is not an allergic reaction.
• Mild Reference anemia Opens New Window, which usually goes away without treatment after 1 to 2 months.
• A lower-than-normal number of Reference platelets Opens New Window in the blood (Reference thrombocytopenia Opens New Window). This condition usually goes away without treatment.
• A lower-than-normal number of Reference neutrophils Opens New Window, a type of white blood cell that helps fight infection. This condition usually goes away without treatment.
• Reference Hepatitis Opens New Window, 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 Reference tonsils Opens New Window that block the throat. Reference Corticosteroids Opens New Window 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.

While it is not a complication specific to mono, a serious disease known as Reference Reye syndrome Opens New Window can develop if you give aspirin to a person younger than 20 to treat symptoms of mono. Aspirin should not be used to treat symptoms of mono. Other medicines, such as acetaminophen (for example, Tylenol) or ibuprofen (for example, Advil) can help relieve fever and pain caused by mono. Follow all instructions on the label.

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

© 1995-2011, Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Reference Terms of Use. Reference How this information was developed to help you make better health decisions.