Prescription onlyNo lower cost generic available


(Interferon Beta-1A)

  • Injection
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Lowers the frequency of multiple sclerosis exacerbations.

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Prescription onlyNo lower cost generic available

Our bottom line

Avonex (Interferon Beta-1A) is an injectable medicine effective for relapsing, remitting MS and has manageable side effects and weekly dosing.


  • One of the main treatments for relapsing MS that has been around for many years.
  • Injections are given weekly, and not daily like other MS medications.
  • Helps reduce the frequency of MS relapse episodes.
  • Flu-like reactions are the most common side effects and usually go away with continued treatment or can be avoided by using over-the-counter pain and fever-reducing medicines before the injection (like acetaminophen or ibuprofen).
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  • Injection site reactions are common, ranging from localized pain, redness, and swelling to severe skin dryness.
  • Flu-like symptoms are common after interferon injections.
  • It's not clear what type of problems occur if taken during pregnancy.
  • Blood testing is required before and during use of Avonex (Interferon Beta-1A).
  • May not be as effective as other interferons.

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Get the lowest price for your medication, even if you have insurance.

  • (1) 4 syringes of 30mcg/0.5ml dose pack
  • Cost for (1) 4 syringes of 30mcg/0.5ml dose pack of Avonex (Interferon Beta-1A) at pharmacies

What to expect when you take Avonex (Interferon Beta-1A)

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Tips from our pharmacists
  • Inject yourself once a week in your muscle (you need to go deeper than the fat layer between your skin and muscle).
  • Refrigerate the powder and pre-filled syringes and pens.
  • Don't shake the medicine once it is taken out of the refrigerator or mixed.
  • If using the pre-filled syringes, the tiny air bubbles won't hurt you.
  • Avonex (Interferon Beta-1A) can cause flu-like symptoms (headache, fever, muscle pain) right after injections, lasting minutes or hours.
  • Flu-like reactions usually go away with repeated treatments. Taking acetaminophen or ibuprofen 45 minutes before the injection can reduce the uncomfortable feeling.
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Side effects for Avonex (Interferon Beta-1A)

From clinical trials of Avonex / Multiple sclerosis (relapsing) (30 mcg)  ( 684)

  • HeadacheHeadache57% for Avonex vs.55% for placebo
  • Flu-like symptomsFlu-like symptoms49% for Avonex vs.28% for placebo
  • Muscle painMuscle pain28% for Avonex vs.22% for placebo
  • Muscle weaknessMuscle weakness24% for Avonex vs.18% for placebo
  • PainPain23% for Avonex vs.21% for placebo
  • NauseaNausea23% for Avonex vs.19% for placebo
  • FeverFever20% for Avonex vs.9% for placebo
  • ChillsChills19% for Avonex vs.5% for placebo
  • Low mood disorderLow mood disorder18% for Avonex vs.14% for placebo
  • Urinary tract infectionUrinary tract infection17% for Avonex vs.15% for placebo

Risks and Warnings for Avonex (Interferon Beta-1A)

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    • Higher risk if:
    • History of depression or mental illness

    Avonex (Interferon Beta-1A) may increase the risk of suicidal thoughts or behavior. Watch for new or worsening depression or any unusual changes in mood or behavior, especially during the first few months of treatment or when the dose changes. Tell your doctor right away if you have any of these symptoms.

Means that some groups have a high risk of experiencing this side effect

Tips from pharmacists and people taking Avonex (Interferon Beta-1A)

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The FDA category for this medication is C. It is advised that you: Weigh risks vs. benefits
  • Risks from our pharmacists
  • Avonex (Interferon Beta-1A) can cause serious liver injury with the risk increasing during the first 6 months after you start. You'll need to have your liver enzymes tested at 1, 3, and 6 months. If liver enzymes are significantly elevated and you have appetite/weight loss, stomach discomfort, vomiting, and notice dark urine, yellowing of skin/eyes, change in stool color, and skin rash, you should stop taking Avonex (Interferon Beta-1A) until your doctor decides if it's safe to re-start.