Avonex for Multiple Sclerosis Treatment

This injectable drug is used for early-stage MS

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Avonex (interferon beta-1a) is one of the disease-modifying therapies (DMTs) used for the treatment of multiple sclerosis (MS). It is administered as a weekly injection that you can learn to give to yourself. The drug, like other DMTs, is used to prevent MS exacerbations and to prevent disease progression. Avonex is not used for the treatment of acute MS relapses.

Nurse swabbing patient's leg after administering a shot
PhotoAlto/Michele Constantini/ Getty Images


Avonex is one of the interferons, a category of MS DMTs that is effective and relatively safe.

It was approved by the U.S. Food and Drug Administration (FDA) in 1996 for use in relapsing-remitting MS (RRMS). Avonex is also approved for those who experience one episode that meets the criteria of an MS attack but who have not been diagnosed with the disease.

Avonex has been found to be more effective in reducing MS-associated disability when the medication is started earlier in the course of the disease.

Avonex is often chosen as a first-line MS therapy because it only requires one injection per week; other DMTs may require between three to seven injections per week.

This makes Avonex a convenient choice for people who are working full-time, are caring for small children, or don't want to experience too much downtime from side effects.

How It Works

Avonex modulates the immune system by interacting with proteins that are involved in the body's immune responses, such as interleukins and growth factor. It may also have other effects and is believed to work in a way that is similar to the other interferons.


All of the interferons (Copaxone, Rebif, Avonex, Betaseron) reduce the risk of relapses in people with RRMS by about a third. Newer agents are usually studied in comparison to the benchmarks set by interferons when it comes to efficacy, and interferons tend to be safer than many other MS medications.


Avonex is taken at a dose of 30 micrograms (mcg) per week. It is administered as an intramuscular (IM) injection, usually into a thigh muscle.

Ideally, injections should be taken on the same day every week, although they can be as close as five days or as long as 10 days apart if needed.

If you've been prescribed Avonex and absolutely can't give yourself an injection successfully, you can schedule office visits to have someone on your healthcare team inject the medication for you. Alternatively, ask a loved one to learn how to administer the shot.

Side Effects

The side effects of Avonex are similar to other interferon-based therapies and can often manifest as flu-like symptoms, including:

  • Fever
  • Chills
  • Sweating
  • Muscle Aches
  • Fatigue

As many as 61 percent of people taking Avonex will experience these symptoms, which can last between 24 and 36 hours (on average). Many of the flu-like side effects subside over time, although they may last for six months or more.

While Avonex is considered a safe DMT, Avonex can lead to liver damage or liver failure. Depression, suicide, and psychotic disorders have also been reported.


Avonex is not appropriate for everyone. Contraindications include:

  • Pre-existing liver disease or cirrhosis
  • Pregnancy (or active planning to conceive)
  • Breastfeeding (while on the drug or soon after its cessation)
  • Seizure disorders
  • Cardiac problems


Avonex's average retail price range in 2019 is around $7,200 per month (approximately $86,400 per year). Many health insurance plans cover part of the cost of treatment, and copay and out-of-pocket costs can vary.

There is no generic version of this medication.

Patient assistance programs (PAPs) are available to assist with drug reimbursement or copay assistance. For more information, contact Biogen (the drug's manufacturer) at 800-456-2255, or visit AboveMS.com for more information.

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