FAQs about Avonex

Avonex was approved by the U.S. Food and Drug Administration in May 1996 for the treatment of adults with relapsing-remitting MS and active secondary progressive MS. Its use was expanded in 2003 to include clinically isolated syndrome. The Avonex Pen was approved in the U.S. in 2012.

Yes. While Avonex was previously not recommended for pregnant people, U.S. and European labels were updated in recent years to allow its use in pregnant and breastfeeding patients, where clinically necessary. The decisions were based on data from several European registries showing that exposure to interferon beta-based medications before conception or during the first trimester was not associated with fetal problems. However, people who plan to become pregnant should inform their healthcare provider and discuss the risks and benefits of continuing to receive this treatment during pregnancy.

Avonex may cause liver injury. As such, using this treatment with alcohol or other substances that also can damage the liver may increase the risk of liver problems. Patients who drink alcohol are advised to inform their healthcare providers before starting on this medication.

Some patients may see results as soon as six months after starting treatment. In the CHAMPS trial, which investigated Avonex against a placebo in nearly 400 patients with clinically isolated syndrome, a significant reduction in new brain lesions (both total and with active inflammation) could be observed as early as within six months. However, as each person may respond differently to a given medication, a discussion with a healthcare provider is recommended to better understand when and how Avonex is expected to help a particular patient.

While rare, hair loss and weight changes have been reported in clinical trials as possible side effects of Avonex. Individuals who experience such events should discuss these issues with their healthcare team.

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