Avonex contains the active ingredient interferon beta-1a, which is a type of interferon beta and a 166 amino acid glycoprotein. It is available as a sterile liquid injection for intramuscular use, delivered in a prefilled glass syringe or an autoinjector, each providing 30 micrograms of interferon beta-1a. Key inactive ingredients include arginine hydrochloride, glacial acetic acid, polysorbate 20, and sodium acetate trihydrate. Avonex is commonly used for its antiviral activity, with a specific activity of approximately 200 million international units per milligram of interferon beta-1a based on the cytopathic effect bioassay.

How should I use this medication?

Rebif is injected under the skin. Avonex is injected into a muscle. You will be taught how to prepare and give it. Take it as directed on the prescription label. Keep taking it unless your care team tells you to stop.

It is important that you put your used needles and syringes in a special sharps container. Do not put them in a trash can. If you do not have a sharps container, call your pharmacist or care team to get one.

This medication comes with INSTRUCTIONS FOR USE. Ask your pharmacist for directions on how to use this medication. Read the information carefully. Talk to your pharmacist or care team if you have questions.

A special MedGuide will be given to you by the pharmacist with each prescription and refill. Be sure to read this information carefully each time.

Talk to your care team about the use of this medication in children. Special care may be needed.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.

NOTE: This medicine is only for you. Do not share this medicine with others.

What if I miss a dose?

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses. Each dose should be separated by about 48 hours. If you accidentally take a dose on 2 consecutive days, call your care team.

Where should I keep my medication?

Keep out of the reach of children and pets.

Rebif: Store in a refrigerator between 2 and 8 degrees C (36 and 46 degrees F). Do not freeze. If a refrigerator is not available, the medication can be kept cool at or below 25 degrees C (77 degrees F) for up to 30 days. Protect from light. Get rid of any unused medication after the expiration date.

Avonex: Store in a refrigerator between 2 and 8 degrees C (36 and 46 degrees F). Do not freeze. If a refrigerator is not available, the medication can be stored at a temperature at or below 25 degrees C (77 degrees F) for up to 7 days. Protect from light. Remove dose from refrigerator 30 minutes prior to using it. Get rid of any unused medication after the expiration date.

To get rid of medications that are no longer needed or have expired:

• Take the medication to a medication take-back program. Check with your pharmacy or law enforcement to find a location.
• If you cannot return the medication, ask your pharmacist or care team how to get rid of this medication safely.

NOTE: This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.

What side effects may I notice from receiving this medication?

Side effects that you should report to your care team as soon as possible:

• Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
• Heart failure—shortness of breath, swelling of the ankles, feet, or hands, sudden weight gain, unusual weakness or fatigue
• High thyroid levels (hyperthyroidism)—fast or irregular heartbeat, weight loss, excessive sweating or sensitivity to heat, tremors or shaking, anxiety, nervousness, irregular menstrual cycle or spotting
• Infection—fever, chills, cough, sore throat, wounds that don't heal, pain or trouble when passing urine, general feeling of discomfort or being unwell
• Liver injury—right upper belly pain, loss of appetite, nausea, light-colored stool, dark yellow or brown urine, yellowing skin or eyes, unusual weakness or fatigue
• Low red blood cell level—unusual weakness or fatigue, dizziness, headache, trouble breathing
• Low thyroid levels (hypothyroidism)—unusual weakness or fatigue, increased sensitivity to cold, constipation, hair loss, dry skin, weight gain, feelings of depression
• Mood and behavior changes—anxiety, nervousness, confusion, hallucinations, irritability, hostility, thoughts of suicide or self-harm, worsening mood, feelings of depression
• Pulmonary arterial hypertension (PAH)—shortness of breath, unusual weakness or fatigue, swelling of the ankles, hands, or feet, dizziness, feeling faint or lightheaded, chest pain, fast or irregular heartbeat, blue skin or lips
• Seizures
• Stomach pain, bloody diarrhea, pale skin, unusual weakness or fatigue, decrease in the amount of urine, which may be signs of hemolytic uremic syndrome
• TTP—purple spots on the skin or inside the mouth, pale skin, yellowing skin or eyes, unusual weakness or fatigue, fever, fast or irregular heartbeat, confusion, change in vision, trouble speaking, trouble walking
• Unusual bruising or bleeding

Side effects that usually do not require medical attention (report these to your care team if they continue or are bothersome):

• Flu-like symptoms—fever, chills, muscle pain, cough, headache, fatigue
• Pain, redness, or irritation at injection site
• Unusual weakness or fatigue

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What should I tell my care team before I take this medication?

They need to know if you have any of these conditions:

• Depression
• Heart failure
• Immune system problems
• Liver disease
• Low blood counts (white cells, platelets, or red blood cells)
• Suicidal thoughts, plans, or attempt by you or a family member
• An unusual or allergic reaction to interferon beta-1a, other interferons, albumin, other medications, foods, dyes, or preservatives
• Pregnant or trying to get pregnant
• Breast-feeding

What may interact with this medication?

Interactions have not been studied.

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

What should I watch for while using this medication?

Visit your care team for regular checks on your progress. Tell your care team if your symptoms do not start to get better or if they get worse.

You may need blood work while you are taking this medication.

This medication can cause serious side effects. To reduce the risk, your care team may give you other medications to take before receiving this one. Be sure to follow the directions from your care team.

This medication can cause a blood clotting problem called thrombotic thrombocytopenic purpura (TTP). TTP is a rare but serious medical condition that can be deadly. Get medical help right away if you have purple spots on your skin or inside your mouth, pale skin, yellowing skin or eyes, unusual weakness or fatigue, fever, fast or irregular heartbeat, confusion, change in vision, trouble speaking, or trouble walking.