Avonex (interferon beta-1a) is a brand-name drug prescribed for multiple sclerosis (MS) in adults. Avonex comes as a solution in prefilled autoinjector pens and prefilled syringes. It’s given as an intramuscular injection once per week.

Avonex is approved by the Food and Drug Administration (FDA) to treat:

Avonex is a biologic and belongs to a drug class called immunomodulators. Avonex isn’t available in a biosimilar version.

Keep reading for specific information about the dosage of Avonex, including its strength and how to use the medication. For a comprehensive look at Avonex, see this article.

Note: This article describes typical dosages for Avonex provided by the drug’s manufacturer. When using Avonex, always follow the dosage prescribed by your doctor.

The information below describes Avonex’s typical dosage and other details about the drug.

Avonex forms

Avonex comes as a solution in two forms:

  • single-dose prefilled autoinjector pen (Avonex Pen)
  • single-dose prefilled syringe

You give yourself Avonex as an intramuscular injection. (For details, see “How Avonex is given” below.)

Avonex strength

Both forms of Avonex come in one strength of 30 micrograms per 0.5 milliliters of solution (mcg/mL).

Typical dosages

Typically, your doctor will start by prescribing a low dosage. Then they’ll adjust it over time to reach the typical maintenance dosage.

The following information describes dosages that are commonly prescribed or recommended. However, be sure to use the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Dosage for MS

Doctors may prescribe Avonex to treat certain forms of MS. The typically recommended dosing schedule is the same for all of Avonex’s FDA-approved uses.

If your doctor prescribes Avonex for your MS, your starting dose will likely be 7.5 mcg, given once. Your doctor will increase your dose by 7.5 mcg each week for 3 weeks to reach 30 mcg once per week. This is the recommended maintenance dosage of Avonex for people with MS. This is also the maximum dose of Avonex that’s recommended.

The typical dosing schedule when starting Avonex is summarized below:

Treatment weekAvonex dose, given as one injection every week
week 17.5 mcg
week 215 mcg
week 322.5 mcg
weeks 4+30 mcg

If your doctor prescribes the typical dosing schedule, you’ll use the Avostartgrip dose titration kit. The kit can only be used with the Avonex prefilled syringe. The kit contains a set of three different devices that help you measure the exact dose to self-inject. You use each of these devices to measure 7.5 mcg for week 1, 15 mcg for week 2, and 22.5 mcg for week 3. To learn more, see the drug manufacturer’s instructions for use.

When you reach the maintenance dose of 30 mcg once per week, you may use the Avonex prefilled syringe or the auto-injector pen. For more information about different Avonex forms or your specific dosage, talk with your doctor.

Long-term treatment

Avonex is meant to be a long-term treatment. If you and your doctor determine that Avonex is safe and effective for you, you’ll likely use it long term.

Before you start using Avonex, your doctor will discuss your treatment plan with you.

Avonex comes as a solution in single-dose prefilled auto-injector pens and syringes. It’s given as an intramuscular injection.

With an intramuscular injection, you inject the medication into your muscle. You’ll use the auto-injector pen or syringe to give yourself Avonex. Your doctor will give you your first dose during your office visit. Then, they’ll show you (or your caregiver) how to do it. Make sure to inject Avonex according to your prescribed instructions.

You’ll store Avonex pens and syringes in the refrigerator. Do not freeze your Avonex doses.

Here are some other things to keep in mind:

  • Before you inject your dose, allow the auto-injector pen or syringe to sit at room temperature for 30 minutes.
  • Inject the Avonex pen into your upper, outer thigh. Inject the Avonex syringe into your thigh or upper arm.
  • Be sure to choose a different injection site each time you inject Avonex.
  • Take care to avoid areas where your skin is tender, hard, or irritated. This will reduce your risk of injection-related side effects such as bleeding or pain at the injection site.

If you have questions about how to inject Avonex, talk with your doctor or pharmacist. You can also watch the drug manufacturer’s video and read the auto-injector pen and syringe instructions for use.

If you miss a dose of Avonex, inject the dose as soon as you remember. Then continue with your regular schedule the next week. Do not inject two doses to make up for the missed one. If you’re not sure whether you should inject a missed dose or skip it, talk with your doctor or pharmacist.

To help make sure that you don’t miss a dose, try using a medication reminder. This can include setting an alarm or putting a note where you’ll see it, such as on your bathroom mirror or bedside table. You could also download a reminder app on your phone.

It’s important that you don’t use more Avonex than your doctor prescribes. For some medications, using more than the recommended amount may lead to harmful effects or overdose.

If you use more than the recommended amount of Avonex

Call your doctor right away if you believe you’ve used too much Avonex. Another option is to call America’s Poison Centers at 800-222-1222 or use its online tool. If you have severe symptoms, immediately call 911 or your local emergency number, or go to the nearest emergency room.

Below are some frequently asked questions about Avonex and dosage.

Is the dosage of Avonex similar to the dosage of Rebif?

No, the dosage forms, strengths, and how often you take each drug are different. Both Avonex and Rebif (interferon beta-1a) have the same active ingredient. And both are prescribed for certain forms of multiple sclerosis (MS). However, Avonex comes as an intramuscular injection and Rebif comes as a subcutaneous injection.

The dose in micrograms (mcg) for each drug is also different because they have different dosage forms. In addition, Avonex is typically taken once per week and Rebif is usually taken three times per week. Your doctor will prescribe the drug and the dosage that’s right for you.

To learn more about how these drugs compare, talk with your doctor.

How long does it take for Avonex to start working?

Avonex starts to work after your first dose. Because of how the drug works, you likely won’t feel the drug working in your body. But your doctor will monitor you during treatment to check whether the drug is working to treat your condition.

Talk with your doctor if you have questions about what to expect with Avonex treatment.

The dosages in this article are typical dosages provided by the drug’s manufacturer. If your doctor recommends Avonex for you, they’ll prescribe the dosage that’s right for you. Always follow the dosage that your doctor prescribes.

As with any drug, never change your dosage of Avonex without your doctor’s recommendation. If you have questions about the dosage of Avonex that’s best for you, talk with your doctor.

Besides learning about dosage, you may want other information about Avonex. These additional articles might be helpful:

  • More about Avonex: For information about other aspects of Avonex, refer to this article.
  • Details about MS: For details about MS, see our MS hub.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.