Avonex Side Effects

Flu-like symptoms, headaches, and muscle pain are the most common side effects reported with Avonex. Side effects may also include abdominal pain, toothache, and dizziness. In most cases, Avonex side effects are minor and either don't require treatment or can be treated easily. However, you should seek medical attention immediately if you experience unusual bruising or bleeding, thyroid problems, frequent infections, or chest pain.

 

An Introduction to Avonex Side Effects

As with any medicine, side effects are possible with Avonex® (interferon beta-1a); however, not everyone who takes the medication will experience side effects. In fact, most people tolerate it quite well. If side effects do occur, in most cases, they are minor and either require no treatment or can easily be treated by you or your healthcare provider.
 
(This article covers many, but not all, of the possible side effects with Avonex. Your healthcare provider can discuss a more complete list of Avonex side effects with you.)
 

Common Side Effects of Avonex

Avonex has been studied thoroughly in clinical trials.
 In these studies, the side effects that occur in a group of people taking the drug are documented and are then compared to side effects that occur in another group of people not taking the medicine. This way, it is possible to see what side effects occur, how often they appear, and how they compare to the group not taking the medicine.
 
In these studies, the most common Avonex side effects included:
 
  • Headaches -- in up to 58 percent of people
  • Flu-like symptoms -- up to 49 percent
  • Muscle pain -- 29 percent
  • Weakness -- up to 24 percent
  • Nausea -- up to 23 percent
  • General body pain -- up to 23 percent
  • Fever -- up to 20 percent.
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Other common Avonex side effects (occurring in 2 to 19 percent of people) included:
 
  • Chills
  • Abdominal pain (stomach pain)
  • Infections, such as bronchitis or a sinus infection
  • Redness, pain, or irritation at the injection site
  • Toothache
  • Dizziness
  • Joint pain
  • Hair loss (see Avonex and Hair Loss)
  • Eye problems
  • Anemia
  • Migraines
  • Flushing.
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(Avonex Side Effects Continued: Page 2)
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;