9 mins read

Interferon beta-1a is injected under the skin or into a muscle to treat certain forms of multiple sclerosis. Common side effects include flu-like symptoms, and pain, itching, swelling, or redness near where the needle went in. Serious side effects are less common, but may include liver, heart, skin, blood vessel, or mental health problems. Let your health care provider know right away if you have new or worsening depression, anxiety, or thoughts of suicide.

Uses

What is interferon beta-1a used for?

Interferon beta-1a is commonly used to treat certain forms of multiple sclerosis, such as clinically isolated syndrome (CIS), relapsing-remitting disease, and active secondary progressive disease.

Interferon beta-1a may also be used for other conditions as determined by your health care provider.

How does interferon beta-1a work (mechanism of action)?

Multiple sclerosis (MS) is a condition where the immune system attacks the central nervous system (CNS), causing inflammation, damage to the protective covering of nerves, and loss of nerve function. Interferon beta-1a is similar to a natural protein called interferon beta. It seems to help people with MS by reducing inflammation in your body by changing the balance of cytokines (chemical messengers that guide cell growth and activity). 

How is interferon beta-1a supplied (dosage forms)?

Brands and other names

  • Avonex
  • Rebif

Dosage forms and strengths

  • 30 mcg/0.5 mL single-dose prefilled syringe
  • 30 mcg/0.5 mL single-dose prefilled autoinjector
  • 8.8 mcg/0.2 mL, 22 mcg/0.5 mL, 44 mcg/0.5 mL single-dose prefilled syringe
  • 8.8 mcg/0.2 mL, 22 mcg/0.5 mL, 44 mcg/0.5 mL single-dose autoinjector

How should I store interferon beta-1a?

Interferon beta-1a should be stored in the original container (to protect it from light) in the refrigerator, between 36 F and 46 F (2 C and 8 C). If needed, interferon beta-1a may be stored at room temperature, up to 77 F (25 C), for shorter periods of time. Ask your pharmacist if you are unsure how to store your interferon beta-1a product.

Side Effects

What are the most common side effects of interferon beta-1a?

The most common side effects of interferon beta-1a are listed below. These side effects may vary based on the interferon beta-1a product used. Tell your health care provider if you have any of these side effects that bother you.

  • Flu-like symptoms such as a fever, chills, muscle pain, and feeling unusually weak or tired
  • Reactions where the needle went in (see below)
  • Stomach pain
  • Changes in liver function tests
  • Depression (see below)
  • Blood disorders (see below) 

There may be other side effects of interferon beta-1a that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of interferon beta-1a?

While less common, the most serious side effects of interferon beta-1a are described below, along with what to do if they happen.

Severe Allergic Reactions. Interferon beta-1a may cause allergic reactions, which can be serious. Stop using interferon beta-1a and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • A racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Depression, Suicidal Thoughts, or Other Mental Health Conditions. Interferon beta-1a may cause mood or behavior problems in a small number of people. If you are about to harm yourself, call 911 or call or text 988, the Suicide and Crisis Lifeline. Call your health care provider right away if you have any of the following symptoms.

  • New or increased feelings of crankiness, nervousness, anxiety, depression, or other unusual changes in mood or behavior
  • New or increased thoughts of suicide or death
  • Suicide attempt
  • Acting aggressive, angry, or violent
  • Seeing or hearing things that others do not see or hear, also called hallucinations

Liver Damage. Liver damage, also called hepatotoxicity, can happen when using interferon beta-1a. This can be serious and can lead to liver failure. The risk may be higher if you take certain medicines. Call your health care provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness or sleepiness
  • Confusion
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine (pee)
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Injection Site Reactions. Interferon beta-1a commonly causes pain, itching, swelling, or redness near where the needle went in. It may also rarely cause severe damage to the skin and tissue near the injection site. You should not inject interferon beta-1a into skin that is red, bruised, infected, scabbed, broken, painful, or has lumps or bumps. Call your health care provider right away if you have any of the following symptoms. 

  • Swelling, itching, redness, or pain where the needle went in
  • Fluid draining from the injection site
  • Breaks in your skin
  • Discolored skin (blue/black)

Heart Problems. Interferon beta-1a may cause or worsen heart problems, including heart failure, low blood pressure, a fast or abnormal heart beat, chest pain, a heart attack, or a heart muscle problem (cardiomyopathy). Tell your health care provider right away if you have any of the following symptoms of heart problems.

  • Shortness of breath or trouble breathing, especially while lying down
  • Chest pain or tightness
  • A hard time exercising
  • Swelling in your feet, ankles, or legs
  • Peeing frequently, especially at night
  • Unusually fast weight gain
  • Unusual tiredness
  • Fast or abnormal heart beat

Blood Disorders. Interferon beta-1a can cause blood disorders, such as low red blood cell levels (anemia), low platelet levels (thrombocytopenia), and low white blood cell levels (leukopenia). Tell your health care provider right away if you have any of the following symptoms of blood disorders.

  • Fever
  • Shortness of breath
  • Pale or yellowish skin
  • Easy bruising or bleeding
  • Frequent infections
  • Unusual weakness or tiredness
  • Dizziness, lightheadedness, or feeling like you are about to pass out
  • Headache
  • Fast or abnormal heartbeat

Small Blood Vessel Injury. Interferon beta-1a can lead to a serious problem with blood clotting, called thrombotic thrombocytopenic purpura (TTP). TTP is when blood clots form in some parts of your bloodstream, which reduces platelets in the rest of the blood (thrombocytopenia). If the blood vessel damage happens in your kidneys, it can lead to hemolytic uremic syndrome (HUS). This can lead to kidney failure. These conditions need to be treated right away in the hospital, or they can lead to death. Get emergency help if you have any of the following symptoms without another explanation.

  • Fever
  • Shortness of breath
  • Pale or yellowish skin, or your skin or the whites of your eyes turn yellowish (also called jaundice)
  • Changes in your vision
  • Unusual weakness or tiredness
  • Headache, confusion, or slurred speech
  • Fast heartbeat
  • Purplish spots (purpura) on your skin or in your mouth due to bleeding under the skin
  • A reduced need to pee, a low amount of pee, or pee that is pink or has blood in it
  • Swelling in your feet, ankles, or legs
  • Chest pain or pressure
  • Nausea
  • Seizures

Pulmonary Arterial Hypertension. Interferon beta-1a may cause pulmonary arterial hypertension, which is high blood pressure in the arteries of the lungs. This can happen soon after or even years after you start using interferon beta-1a. Call your health care provider right away if you have shortness of breath or tiredness that is new or getting worse.

Seizures. Some people who have used interferon beta-1a have reported having seizures, even if they never had seizures before. There are many types of seizures, and some of them are not easy to recognize. Call your health care provider right away if you have any of the following signs that a seizure is happening or could happen.

  • Muscle twitching, jerking, spasms, tremors, or other uncontrolled movements
  • Stiffening of your arms and legs
  • Feeling anxious, nervous, confused, or a sense of dread
  • Feeling dizzy or lightheaded
  • Falling or losing consciousness

Autoimmune Conditions. Interferon beta-1a may cause a new autoimmune disorder to develop, which means the immune system attacks the body’s own tissues. These disorders may cause problems with your blood, thyroid, or liver. Your health care provider may monitor you for these conditions. Tell your health care provider about any new symptoms that you may get.

Warnings & Precautions

Who should not use interferon beta-1a?

Allergies to Ingredients. People who are allergic to any of the following should not use interferon beta-1a.

  • Interferon beta-1a
  • Avonex 
  • Rebif
  • Human albumin (some products)

Your pharmacist can tell you all of the ingredients in the specific interferon beta-1a products they stock.

What should I know about interferon beta-1a before using it?

Do not use interferon beta-1a unless it has been prescribed to you by a health care provider. Use it as prescribed. Do not change your dose or schedule unless your health care provider says to do so. This medicine is either injected under the skin or into a muscle. Read and follow the “Instructions for Use” that come with your medicine. Make sure that you or a caregiver understands how to properly prepare and use interferon beta-1a. If you have any questions, talk to your health care provider.

Do not share interferon beta-1a with other people, even if they have the same condition as you. It may harm them.

Keep interferon beta-1a out of the reach of children. When this medicine is kept in a refrigerator, take special care to keep it away from children who also use the refrigerator.

Do not inject interferon beta-1a into skin that is red, bruised, infected, scabbed, broken, painful, or has lumps or bumps. Use a different injection site each time you inject this medicine. Two hours after injecting this medicine, check your injection site for swelling, redness, or tenderness. Call your health care provider if you have a skin reaction that does not clear up in a few days. 

Interferon beta-1a should only be used one time. You will use a new syringe or autoinjector pen for each dose. Throw away any unused medicine after injecting your dose. Do not reuse needles, syringes, or autoinjectors. Throw them away in a sharps container.

Interferon beta-1a may cause flu-like symptoms such as a fever, chills, muscle pain, and feeling unusually weak or tired. If you have these side effects, your health care provider may recommend an over-the-counter pain or fever medicine on the days you inject interferon beta-1a.

What should I tell my health care provider before using interferon beta-1a?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if interferon beta-1a is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Blood clots or bleeding problems
  • Low blood cell counts
  • Thyroid problems
  • Any other autoimmune conditions
  • Depression, thoughts of suicide or death, suicide attempts, or other mental health conditions
  • Liver problems
  • Seizures
  • Heart problems, including heart failure
  • Pulmonary arterial hypertension

Rubber or Latex Allergy. Some interferon beta-1a products contain natural rubber latex and may cause allergic reactions in some people. Tell your health care provider if you are allergic to rubber or latex. 

Vaccines. Talk with your health care provider about any vaccines that you may need. You should not receive certain vaccines right before or while using interferon beta-1a. Tell your health care provider about any vaccines you have recently received or have scheduled.

Pregnancy. It is not known if or how interferon beta-1a could affect pregnancy or harm an unborn baby. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. Interferon beta-1a passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should use interferon beta-1a while breastfeeding.

Interactions

Does interferon beta-1a interact with foods or drinks?

There are no known interactions between interferon beta-1a and foods or drinks.

It is unknown if drinking alcohol will affect interferon beta-1a. The risk of liver problems may be increased if you drink alcohol while using interferon beta-1a.

Does interferon beta-1a interact with other medicines (drug interactions)?

There are no known interactions between interferon beta-1a and other medicines. Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much interferon beta-1a?

If you or someone else has used too much interferon beta-1a, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of interferon beta-1a?

If you miss a dose, use it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only use the next dose. Do not use double or extra doses. If you miss a dose and are not sure what to do, ask your health care provider.

Look up another drug