Generic Name: interferon beta-1a (in-ter-FEER-on BAY-ta-1a) (Intramuscular route, Subcutaneous route)
Medically reviewed by Drugs.com. Last updated on June 7, 2020.
Commonly used brand name(s)
In the U.S.
- Avonex Pen
- Rebif Rebidose
- Rebif Rebidose Titration Pack
Available Dosage Forms:
Therapeutic Class: Immunological Agent
Pharmacologic Class: Interferon, Beta (class)
Uses for Avonex
Interferon beta-1a injection is used to treat the relapsing forms of multiple sclerosis (MS), including clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease. This medicine will not cure MS, but it may slow some of the disabling effects and decrease the number of relapses of the disease. Interferons are natural substances that are produced in the body to help fight infections. Interferon beta-1a is a synthetic (man-made) version of these substances.
This medicine is available only with your doctor's prescription.
Before using Avonex
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies have not been performed on the relationship of age to the effects of interferon beta-1a injection in the pediatric population. Safety and efficacy have not been established.
Although appropriate studies on the relationship of age to the effects of interferon beta-1a injection have not been performed in the geriatric population, geriatric-specific problems are not expected to limit the usefulness of interferon beta-1a injection in the elderly. However, elderly patients are more likely to have age-related kidney, liver, or heart problems, which may require caution in patients receiving interferon beta-1a injection.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other medical problems
The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:
- Alcohol abuse, history of or
- Angina (severe chest pain) or
- Autoimmune disorders (eg, autoimmune hepatitis, idiopathic thrombocytopenia) or
- Bone marrow problems (decreased amounts of red or white blood cells in your body), history of or
- Congestive heart failure or
- Depression or mental problems, history of or
- Heart disease (eg, cardiomyopathy) or
- Heart rhythm problems (eg, arrhythmia) or
- Liver disease or
- Seizures or epilepsy, history of or
- Thyroid problems—Use with caution. May make these conditions worse.
- Allergy to human albumin, history of—Avonex® powder and Rebif® prefilled syringe and autoinjector should not be used in patients with this condition.
- Infection—May decrease your body's ability to fight an infection.
Proper use of Avonex
This section provides information on the proper use of a number of products that contain interferon beta-1a. It may not be specific to Avonex. Please read with care.
A nurse or other trained health professional will give you this medicine. You may also be taught how to give your medicine at home. This medicine is given as a shot under your skin or into a muscle. A nurse or other trained health professional should watch the first Avonex® injection you give yourself.
If you are injecting interferon beta-1a yourself, use it exactly as directed by your doctor. Do not change your dose or dosing schedule without checking first with your doctor. The exact amount of medicine you need has been carefully worked out. Using too much will increase the risk for side effects, while using too little may not improve your condition.
You will be shown the body areas where this shot can be given. Use a different body area each time you give yourself a shot. Keep track of where you give each shot to make sure you rotate body areas.
Use only the brand of this medicine that your doctor prescribed. Different brands may not work the same way.
Rebif® comes as an autoinjector or a prefilled syringe. It works best if you use it at the same time (usually in the late afternoon or evening) on the same 3 days (eg, Monday, Wednesday, and Friday) at least 48 hours apart each week.
Avonex® comes as a prefilled autoinjector pen, a prefilled syringe, or a powder. The powder must be mixed with sterile water before it is given. Do not shake the vial after you add the water. Gently swirl the water and medicine together to mix. The mixture should be clear or slightly yellow. Do not use the mixture if you see particles in it. Use the medicine as soon as possible after mixing. If you cannot give your shot right away, you can keep the syringe in the refrigerator for up to 6 hours. After 6 hours, throw the medicine away and mix another dose.
Use a new needle, unopened vial, or syringe each time you inject your medicine. Do not use any other needle for the prefilled autoinjector pen.
Each package of medicine contains a Medication Guide and a sheet called Instructions for Use. Read this information carefully and make sure you understand:
- How to prepare the injection.
- How to use disposable syringes or autoinjectors.
- How to store the syringes or autoinjectors.
The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For injection dosage form:
- For multiple sclerosis:
- Avonex®: At first, 7.5 micrograms (mcg) injected into a muscle once a week on the same day (eg, every Monday at bedtime). Your doctor will increase your dose by 7.5 mcg each week for the next 3 weeks until you reach 30 mcg weekly.
- Rebif®: At first, 4.4 or 8.8 mcg injected under the skin 3 times a week. Your doctor will adjust your dose as needed.
- Children—Use and dose must be determined by your doctor.
- For multiple sclerosis:
If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Avonex®: If you miss a dose, give it as soon as you can. Go back to your regular schedule the following week. Do not use this medicine 2 days in a row.
Rebif®: If you miss a dose, give it as soon as you can. Skip the next day and give your regular dose 48 hours later. Go back to your regular schedule the following week. Do not use this medicine 2 days in a row.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Store in the refrigerator. Do not freeze.
Store prefilled autoinjector pens, prefilled syringes, or vials in the refrigerator. Do not freeze. If refrigeration is not available, Rebif® prefilled syringes and Avonex® powder vials may be kept for up to 30 days at room temperature, away from heat (temperatures above 77 degrees F) and direct light. Avonex® prefilled autoinjector pens and prefilled syringes may be stored for up to 7 days at room temperature, away from heat (temperatures above 77 degrees F) and direct light. Allow Avonex® prefilled autoinjector pens and prefilled syringes to warm to room temperature before injection by removing from the refrigerator for about 30 minutes. Do not heat them in a microwave oven or in hot water.
Put the used needles into a hard, closed container that the needles cannot poke through. Keep this container away from children and pets.
Precautions while using Avonex
It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.
This medicine may cause some people to be anxious, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. If you or your caregiver notice any of these side effects, tell your doctor right away.
Check with your doctor right away if you have dark urine, persistent loss of appetite, flu-like symptoms, headache, continuing vomiting, general feeling of tiredness or weakness, light-colored stools, right upper stomach pain or tenderness, or yellow eyes or skin. These could be symptoms of a serious liver problem.
This medicine may cause serious allergic reactions, including anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Call your doctor right away if you have a rash, itching, hoarseness, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth while you are using this medicine.
This medicine may lower the number of white blood cells in the blood. This will increase your chance of getting an infection. It can also lower the number of platelets in the blood. Platelets are necessary for proper blood clotting. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:
- If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.
- Check with your doctor immediately if you notice any unusual bleeding or bruising, black, tarry stools, blood in the urine or stools, or pinpoint red spots on your skin.
- Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.
- Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else in the meantime.
- Be careful not to cut yourself when you are using sharp objects, such as a safety razor or fingernail or toenail cutters.
- Avoid contact sports or other situations where bruising or injury could occur.
This medicine may cause redness, pain, or swelling at the injection site. Some patients have developed skin infections or a permanent depression (necrosis) under the skin at the injection site. Contact your doctor right away if you notice depressed or indented skin, blue-green to black skin discoloration, or pain, redness, or sloughing (peeling) of the skin.
This medicine commonly causes a flu-like reaction, with aching muscles, chills, fever, headaches, joint pain, and nausea. Using your shot at bedtime may allow you to sleep through the symptoms. Your doctor may want you to take a medicine to help control the pain or fever (eg, acetaminophen or ibuprofen). Carefully follow your doctor's instructions about how to prevent or treat these symptoms.
This medicine contains albumin, which comes from human blood. Some human blood products have transmitted certain viruses to people who have received them, although the risk is low. Human donors and donated blood are both tested for viruses to keep the transmission risk low. Talk with your doctor about this risk if you are concerned. The Avonex® prefilled autoinjector pen and prefilled syringe do not contain albumin which comes from donated human blood.
The tip cap of the Avonex® prefilled syringe contains dry natural rubber (a derivative of latex), which may cause allergic reactions in people who are sensitive to latex. Tell your doctor if you have a latex allergy before you start using this medicine.
Avonex side effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
- Black, tarry stools
- chest pain
- flu-like symptoms
- joint pain
- muscle aches
- painful or difficult urination
- sores, ulcers, or white spots on the lips or in the mouth
- swollen glands
- trouble breathing
- unusual bleeding or bruising
- unusual tiredness or weakness
- Clumsiness or unsteadiness
- decreased hearing
- difficulty with swallowing
- feeling of warmth
- hives or itching
- mood changes, especially with thoughts of suicide
- muscle spasms
- pain or discharge from the vagina
- pelvic discomfort, aching, or heaviness
- redness of the face, neck, arms, and occasionally, upper chest
- redness, swelling, or tenderness at the injection site
- runny or stuffy nose
- skin lesions
- sore throat
- speech problems
- stomach pain
- swelling of the face, lips, or eyelids
- general feeling of discomfort or illness
- loss of appetite
- painful blisters on trunk of the body
- painful cold sores or blisters on the lips, nose, eyes, or genitals
Incidence not known
- Bleeding gums
- blood in the urine or stools
- bloody nose
- chest discomfort
- dark urine
- decreased urine output
- depressed mood
- dilated neck veins
- dry skin and hair
- extreme fatigue
- fast, irregular, or pounding heartbeat
- feeling cold
- general tiredness and weakness
- hair loss
- heavier menstrual periods
- high fever
- irregular breathing
- light-colored stools
- loss of bladder control
- mental depression
- mood or other mental changes
- muscle cramps and stiffness
- nausea or vomiting
- pale skin
- persistent loss of appetite
- pinpoint red spots on the skin
- puffiness or swelling of the eyelids, or around the eyes, face, lips, or tongue
- redness, blistering, peeling, or loosening of the skin
- sensitivity to heat
- skin rash
- slowed heartbeat
- sudden loss of consciousness
- swelling of the face, fingers, feet, or lower legs
- swelling of the mouth or throat
- tightness in the chest
- tightness in the throat
- upper right stomach pain or tenderness
- weight gain or loss
- yellow eyes and skin
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
- sour stomach
- Hair loss
- trouble sleeping
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Frequently asked questions
- How and where do you inject Rebif?
- How does Avonex work for Multiple Sclerosis (MS)?
- What is Rebif used for and how does it work?
- How long can Avonex be unrefrigerated?
- Does Rebif suppress the immune system?
- How do you use the Avonex pen injector?
More about Avonex (interferon beta-1a)
- Side Effects
- During Pregnancy
- Dosage Information
- Drug Interactions
- En Español
- 38 Reviews
- Drug class: interferons
- FDA Alerts (1)
Related treatment guides
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.