Rebif (interferon beta-1a) is a prescription drug used to treat some types of multiple sclerosis. The drug comes as a liquid solution for injection under the skin. It’s usually given three times per week.

Rebif is used in adults to treat certain types of multiple sclerosis (MS). They include:

Rebif may also be prescribed to treat clinically isolated syndrome, which often (but not always) turns into MS.

The active ingredient in Rebif is interferon beta-1a. (An active ingredient is what makes a drug work.) Rebif belongs to a group of drugs called immunomodulators and is a biologic drug. Biologics are made from living cells.

This article describes the dosages of Rebif, as well as its strengths and how it’s given. To learn more about Rebif, see this in-depth article.

This section describes the usual dosages of Rebif.

What is Rebif’s form?

Rebif is available as a liquid solution that’s given as an injection under your skin. It’s available in either a single-dose prefilled syringe or a single-dose prefilled auto-injector. Auto-injectors can make it easier to administer your doses of the drug.

What strengths does Rebif come in?

Rebif comes in three strengths:

  • 8.8 micrograms (mcg) in 0.2 milliliters (mL) solution
  • 22 mcg in 0.5 mL solution
  • 44 mcg in 0.5 mL solution

What are the usual dosages of Rebif?

Your doctor will likely start you on a low dosage and adjust it over time to reach the right amount for you. They’ll ultimately prescribe the smallest dosage that provides the desired effect.

The information below describes dosages that are commonly used or recommended. But be sure to follow the dosage your doctor prescribes for you. They’ll determine the best dosage to fit your needs.

Dosage for multiple sclerosis (MS)

The typical Rebif dosage for adults with MS is either 22 mcg or 44 mcg given as an injection under the skin three times per week. Your dosage depends on the severity of your condition and how you react to Rebif.

Your doctor will start you on a low Rebif dosage and slowly increase it over a few weeks to see how you respond to treatment.

Your starting dosage will be either 4.4 mcg or 8.8 mcg three times per week. Your doctor will increase your dosage every 2 weeks until you reach your prescribed dosage of either 22 mcg or 44 mcg three times per week.

Below are dosing schedules for the 22-mcg and 44-mcg dosages, each injected three times per week.

Dosing schedule for 22-mcg dosage

  • Weeks 1 and 2: 4.4 mcg (half dosage of 8.8-mcg syringe)
  • Weeks 3 and 4: 11 mcg (half dosage of 22-mcg syringe)
  • Weeks 5 and beyond: full dosage of 22-mcg syringe

Dosing schedule for 44-mcg dosage

  • Weeks 1 and 2: 8.8 mcg (full dosage of 8.8-mcg syringe)
  • Weeks 3 and 4: 22 mcg dosage (full dosage of 22-mcg syringe)
  • Weeks 5 and beyond: full dosage of 44-mcg syringe

Your doctor will explain your dosing schedule and how to slowly increase your Rebif injections until you reach the right amount for you. Talk with them about any dosage or dosing schedule concerns or questions you may have.

Is Rebif used long term?

Yes, Rebif is usually a long-term treatment. If you and your doctor determine that it’s safe and effective for your condition, you’ll likely use it long term.

Dosage adjustments

In certain cases, you may need a dosage adjustment for Rebif.

Rebif can cause liver damage including liver failure. Tell your doctor if you have liver problems. Before starting Rebif and throughout your treatment, your doctor will likely monitor your liver function.

Call your doctor right away if you develop symptoms of liver problems. These include:

  • nausea
  • lack of appetite
  • dark urine
  • jaundice (yellowing of your skin or the whites of your eyes)

Your doctor will decide whether to lower your dosage of Rebif or have you stop treatment.

If you have questions about whether you need a Rebif dosage adjustment, talk with your doctor.

The dosage of Rebif you’re prescribed may depend on several factors. These include:

  • the type and severity of the condition you’re using the drug to treat
  • other medications you take
  • other conditions you may have (see the “Dosage adjustments” section above)

Rebif comes as a liquid solution that’s injected under your skin. You’ll administer doses three times per week, such as on Monday, Wednesday, and Friday. Your injections of Rebif should be at least 48 hours apart. Try to inject your dose of Rebif around the same time and days each week. This will help keep consistent levels of the drug in your body to best treat your condition.

Your doctor will start you on a low Rebif dosage to see how you respond to treatment. Then, they’ll slowly increase your dosage over a few weeks.

Your doctor or another healthcare professional will show you how to give yourself Rebif injections at home. You’ll likely administer your first dose of Rebif at your doctor’s office.

You’ll typically inject Rebif into your buttock, stomach, thigh, or the outer part of your upper arm. Be sure to rotate your injection site each time you give yourself a dose. Do not inject Rebif in areas of skin that are irritated, bruised, broken, or infected. And do not reuse Rebif prefilled syringes or auto-injector pens.

Your doctor may suggest you take a pain- or fever-reducing medication such as acetaminophen or ibuprofen just before or after your Rebif injection. This can help lower your risk of flu-like side effects from Rebif.

For step-by-step instructions on how to give yourself Rebif injections, check out pages 23–27 of the drug’s prescribing information. You can also talk with your doctor or pharmacist about how to give yourself doses of Rebif.

Accessible drug containers and labels

Some pharmacies provide medication labels that:

  • have large print
  • use braille
  • feature a code you can scan with a smartphone to change the text to audio

Your doctor or pharmacist may be able to recommend pharmacies that offer these accessibility features if your current pharmacy doesn’t.

If you miss a dose of Rebif, inject it as soon as you remember. Then, alter your dosing schedule to give your next Rebif dose after 48 hours have passed. Never give two doses of Rebif within 48 hours to catch up on a missed dose. This can increase your risk of serious side effects. If you’re not sure whether you should inject a missed dose, talk with your doctor or pharmacist.

If you need help remembering to inject your dose of Rebif on time, try using a medication reminder. This can include downloading a reminder app on your phone.

Do not inject more Rebif than your doctor prescribes, as this can lead to harmful effects.

What to do in case you inject too much Rebif

Call your doctor right away if you think you’ve injected too much Rebif. You can also call 800-222-1222 to reach America’s Poison Centers or use its online resource. But if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.

Below are answers to some commonly asked questions about Rebif’s dosage.

Is Rebif’s dosage similar to that of Avonex?

No, it’s not. Rebif and Avonex both have the same active ingredient (interferon beta-1a) and are approved to treat certain types of MS. Both drugs also belong to the immunomodulator group of drugs and are biologics made from living cells.

However, the dose in micrograms (mcg) for each drug differs, as do how often and where each drug is injected. For example, Rebif comes as a liquid solution in three strengths and is injected under your skin three times per week. Avonex comes as a liquid solution in one strength (30 mcg) and is injected into a muscle once per week.

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

How long does it take for Rebif to start working?

Rebif works by lowering the number of MS flare-ups you have. How long it takes the drug to work may depend on individual factors, such as the severity of your MS symptoms. While it’s hard to predict how soon Rebif may work to manage your condition, you should notice fewer flare-ups as you continue treatment.

Your doctor will monitor you during Rebif treatment to be sure the drug is effectively helping to manage your condition. Talk with them if you have other questions about what to expect from treatment.

The sections above describe the usual dosages provided by the drug manufacturer. If your doctor recommends Rebif for you, they’ll prescribe the dosage that’s right for you.

Remember, you should not change your dosage of Rebif without your doctor’s recommendation. Only inject Rebif exactly as prescribed. Talk with your doctor if you have questions or concerns about your current dosage. Examples of questions you may want to ask include:

  • Will I be prescribed a lower dose of Rebif if I experience side effects when I begin treatment?
  • Would the higher dose of Rebif work better to treat my condition?
  • How does the dosage of Rebif compare with that of Copaxone?

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Disclaimer: Healthline 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.