• Heart problems, including heart failure. While
AVONEX is not known to have any direct effects on
the heart, a few patients who did not have a history
of heart problems developed heart muscle problems
or congestive heart failure after taking AVONEX. If
you already have heart failure, AVONEX may cause
your heart failure to get worse. Call your healthcare
provider right away if you have worsening symptoms
of heart failure such as shortness of breath or swelling
of your lower legs or feet while using AVONEX.
• Some people using AVONEX may have other heart
problems including low blood pressure, fast or
abnormal heart beat, chest pain, and heart attack
or heart muscle problem (cardiomyopathy).
• Blood problems. AVONEX can affect your bone
marrow and cause low red and white blood cell,
and platelet counts. In some people, these blood
cell counts may fall to dangerously low levels. If
your blood cell counts become very low, you can get
infections and problems with bleeding and bruising.
• Seizures. Some patients have had seizures while
taking AVONEX, including patients who have never
had seizures before.
• Infections. Some people who take AVONEX may get an
infection. Symptoms of an infection may include fever,
chills, pain or burning with urination, urinating often,
bloody diarrhea, and coughing up mucus.
• Thyroid problems. Some people taking AVONEX
develop changes in their thyroid function. Symptoms
of thyroid changes include problems concentrating,
feeling cold or hot all the time, weight changes, and
Tell your healthcare provider right away if you
have any of the symptoms listed above.
The most common side effects of AVONEX include:
• Flu-like symptoms. Most people who take AVONEX
have flu-like symptoms early during the course of
therapy. Usually, these symptoms last for a day after
the injection. You may be able to manage these flu-like symptoms by taking over-the-counter pain and
fever reducers. For many people, these symptoms
lessen or go away over time. Symptoms may include
muscle aches, fever, tiredness, and chills.
Call your doctor for medical advice about side effects.
You may report side effects to FDA at 1-800-FDA-1088.
For additional important safety information, please see the brief summary of the Medication Guide on
the following page.
Visit AVONEX.com/PEN to learn more.
AVONEX, BIOGEN IDEC, and their respective logos are registered trademarks of Biogen Idec.
AVONEX PEN is a registered trademark of Biogen Idec.