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Generic name: interferon beta-1bin-ter-FEAR-on-BAY-ta-1b ]
Drug class: Interferons

Medically reviewed by Judith Stewart, BPharm. Last updated on Nov 2, 2022.

What is Extavia?

Extavia is made from human proteins. Extavia is similar to certain interferon proteins that are produced in the body. Interferons help the body fight viral infections.

Extavia is a prescription medicine used to treat relapsing forms of multiple sclerosis (MS). This medicine will not cure MS, but it may decrease flare-ups.

It is not known if Extavia is safe and effective in children. .


Extavia may be harmful to an unborn baby, or may cause a miscarriage. Do not use Extavia if you are pregnant. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

Before using Extavia, tell your doctor if you are allergic to any drugs, or if you have liver disease, a thyroid disorder, epilepsy or other seizure disorder, a bleeding or blood-clotting disorder, anemia (low red blood cells), or a history of depression or suicidal behavior.

Some people have thoughts about suicide while taking interferon beta-1b. Stay alert to changes in your mood or symptoms. Report any new or worsening symptoms to your doctor.

Interferon beta-1b can harm your liver. Call your doctor at once if you have nausea, vomiting, itching, bruising or bleeding, or yellowing of your skin or eyes.

To be sure Extavia is not causing harmful effects, your blood and liver function will need to be tested on a regular basis. Your thyroid function may also need to be tested. Do not miss any scheduled appointments.

Before taking this medicine

You should not use Extavia if you are allergic to interferon beta, albumin, or mannitol.

To make sure Extavia is safe for you, tell your doctor if you have:

  • liver disease;

  • heart problems;

  • a seizure;

  • depression, anxiety, or sleep problems;

  • a bleeding or blood-clotting disorder;

  • low white blood cell (WBC) counts;

  • anemia (lack of red blood cells); or

  • an allergy to latex.

Tell your doctor if you are pregnant or breastfeeding.

How should I use Extavia?

Use Extavia exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.

Extavia is injected under the skin, usually every other day. A healthcare provider may teach you how to properly use the medication by yourself.

Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you don't understand all instructions.

Prepare an injection only when you are ready to give it. Do not use if the medicine looks cloudy, has changed colors, or has particles in it. Call your pharmacist for new medicine.

Your healthcare provider will show you where on your body to inject Extavia. Use a different place each time you give an injection. Do not inject into the same place two times in a row.

You will need frequent medical tests.

Store unmixed Extavia and the diluent at cool room temperature away from moisture and heat.

After mixing, store the medicine in the refrigerator and use within 3 hours. Do not freeze.

Each single-use vial (bottle) or prefilled syringe is for one use only. Throw it away after one use, even if there is still medicine left inside. Throw away any Extavia that is not used within 3 months.

Use a needle and syringe only once and then place them in a puncture-proof "sharps" container. Follow state or local laws about how to dispose of this container. Keep it out of the reach of children and pets.

Dosing information

Usual Adult Dose for Multiple Sclerosis:

Initial dose: 0.0625 mg subcutaneously every other day, and increased (in 25% increments) every 2 weeks, over a 6 week period, to maintenance dose
Maintenance dose: 0.25 mg subcutaneously every other day

Schedule for dose titration:
Weeks 1 and 2: 0.0625 mg subcutaneously every other day (25% of recommended dose)
Weeks 3 and 4: 0.125 mg subcutaneously every other day (50% of recommended dose)
Weeks 5 and 6: 0.1875 mg subcutaneously every other day (75% of recommended dose)
Week 7 and beyond: 0.25 mg subcutaneously every other day (100% of recommended dose)

Use: For the treatment of relapsing forms of multiple sclerosis to reduce the frequency of clinical exacerbations. Patients with multiple sclerosis in whom efficacy has been demonstrated include patients who have experienced a first clinical episode and have MRI features consistent with multiple sclerosis.

What happens if I miss a dose?

Use the missed dose as soon as you remember. Then wait at least 48 hours (2 days) before using another injection, and restart your dosing schedule at that time. Do not use more than one injection every 48 hours.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while using Extavia?

Avoid injecting this medicine into skin that is sore, red, or infected.

Avoid drinking alcohol. It may increase your risk of liver problems.

Extavia side effects

Get emergency medical help if you have signs of an allergic reaction to Extavia: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Some patients using interferon medicines have become very depressed or had thoughts of suicide. Report any new or worsening symptoms of depression to your doctor, such as: mood or behavior changes, anxiety, trouble sleeping, hallucinations, or if you feel impulsive, hostile, aggressive, depressed, or have thoughts about suicide or hurting yourself.

Stop using Extavia and call your doctor at once if you have:

  • fever, chills, sweating, tiredness, body aches;

  • a seizure;

  • pain, swelling, redness, or skin changes where an injection was given;

  • heart problems--chest tightness, swelling, rapid weight gain, trouble lying flat in bed, feeling short of breath;

  • liver problems--nausea, vomiting, itching, easy bruising, unusual bleeding, dark urine, jaundice (yellowing of your skin or eyes); or

  • new or worsening symptoms of lupus--joint pain, and a skin rash on your cheeks or arms that worsens in sunlight.

Common Extavia side effects may include:

  • low white blood cell counts;

  • abnormal liver function tests;

  • headache, weakness;

  • sleep problems (insomnia);

  • stomach pain;

  • muscle pain, stiffness, or weakness;

  • rash;

  • flu symptoms; or

  • a skin reaction where the medicine was injected.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Extavia?

Other drugs may interact with interferon beta-1b, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Extavia only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.