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Avonex Pen – Interferon Beta-1a (Intramuscular Route, Subcutaneous Route)


Description and Brand Names of Avonex Pen – Interferon Beta-1a (Intramuscular Route, Subcutaneous Route)

US Brand Name

  1. Avonex
  2. Avonex Pen
  3. Rebif
  4. Rebif Rebidose
  5. Rebif Rebidose Titration Pack


Interferon beta-1a injection is used to treat the relapsing forms of multiple sclerosis (MS). This medicine will not cure MS, but it may slow some 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.

This product is available in the following dosage forms:

  • Solution
  • Kit

Before Using Avonex Pen – Interferon Beta-1a (Intramuscular Route, Subcutaneous Route)

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.


No information is available on the relationship of age to the effects of interferon beta-1a in geriatric patients.



Studies in women suggest that this medication poses minimal risk to the infant when used during breastfeeding.

Drug Interactions

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 is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

  • Rotavirus Vaccine, Live

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.

  • Zidovudine

Other Interactions

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:

  • Allergy to human albumin, history of – Avonex® powder and Rebif® prefilled syringe and autoinjector should not be used in patients with this condition.
  • Angina (severe chest pain) or
  • Autoimmune disorders (e.g., 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 (e.g., cardiomyopathy) or
  • Heart rhythm problems (e.g., arrhythmia) or
  • Liver disease or
  • Seizures or epilepsy, history of or
  • Thyroid problems – Use with caution. May make these conditions worse.
  • Infection – May decrease your body’s ability to fight infection.

Proper Use of Avonex Pen – Interferon Beta-1a (Intramuscular Route, Subcutaneous Route)

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.

If you are injecting interferon beta-1a yourself, use it exactly as directed by your doctor. Do not use more or less of it, and do not use it more often than your doctor ordered. 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 of 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 three days (e.g., 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 interferon beta-1a injection contains a medication guide and patient instruction sheet. Read this sheet carefully and make sure you understand:

  • How to prepare the injection.
  • Proper use of disposable syringes.
  • How to give the injection.
  • How long the injection is stable.

If you have any questions about any of this, check with your doctor.


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 (MS):

      • Adults –

        • For Avonex®:

          • 30 micrograms (mcg) injected into a muscle once a week, on the same day (e.g., every Monday right before bedtime). Your doctor may choose a different dose (more or less) if necessary.
        • For Rebif®:

          • At first, 4.4 or 8.8 mcg injected under the skin three times a week. Your doctor will adjust your dose as needed.
      • Children – Use and dose must be determined by your doctor.

Missed Dose

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.

If you miss a dose or forget to use your medicine, use it as soon as you can. This will then change the time for your next dose. After using the missed dose, use your next regular dose of Rebif® 48 hours later and go back to your regular schedule the following week. For Avonex®, if your next regular dose is less than 2 days away, call your doctor. For either brand, do not use extra medicine to make up for a missed dose and do not use this medicine two 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 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 (remove from the refrigerator for about 30 minutes) before injection but do not heat in a microwave oven or in hot water.

Throw the used needles away in a hard, closed container that the needles cannot poke through. Keep this container away from children and pets.


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.

Avoid alcohol while you are taking this medicine. It can cause serious liver problems.

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 any of these side effects at the injection site: 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, headache, 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 for pain and fever (e.g., acetaminophen or ibuprofen) to help control these effects. Follow your doctor’s instructions carefully 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.

Side Effects of Avonex Pen – Interferon Beta-1a (Intramuscular Route, Subcutaneous Route)

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:

More common

  1. Black, tarry stools
  2. chest pain
  3. chills
  4. cough
  5. diarrhea
  6. fever
  7. flu-like symptoms
  8. headache
  9. joint pain
  10. muscle aches
  11. nausea
  12. pain
  13. painful or difficult urination
  14. shortness of breath
  15. sores, ulcers, or white spots on the lips or in the mouth
  16. swollen glands
  17. unusual bleeding or bruising
  18. unusual tiredness or weakness

Less common

  1. Abdominal or stomach pain
  2. clumsiness or unsteadiness
  3. convulsions (seizures)
  4. decreased hearing
  5. difficulty with swallowing
  6. dizziness
  7. fainting
  8. feeling of warmth
  9. hives or itching
  10. mood changes, especially with thoughts of suicide
  11. muscle spasms
  12. pain or discharge from the vagina
  13. pelvic discomfort, aching, or heaviness
  14. redness of the face, neck, arms, and occasionally, upper chest
  15. redness, swelling, or tenderness at the injection site
  16. runny or stuffy nose
  17. skin lesions
  18. sneezing
  19. sore throat
  20. speech problems
  21. swelling of the face, lips, or eyelids
  22. troubled breathing


  1. Earache
  2. general feeling of discomfort or illness
  3. loss of appetite
  4. painful blisters on trunk of body
  5. painful cold sores or blisters on the lips, nose, eyes, or genitals

Incidence not known

  1. Bleeding gums
  2. blood in the urine or stools
  3. bloody nose
  4. chest discomfort
  5. confusion
  6. constipation
  7. dark urine
  8. decreased urine output
  9. depressed mood
  10. dilated neck veins
  11. dry skin and hair
  12. extreme fatigue
  13. fast, irregular, or pounding heartbeat
  14. feeling cold
  15. general tiredness and weakness
  16. hair loss
  17. heavier menstrual periods
  18. high fever
  19. irregular breathing
  20. light-colored stools
  21. loss of bladder control
  22. mental depression
  23. mood or other mental changes
  24. muscle cramps and stiffness
  25. nausea or vomiting
  26. nervousness
  27. pale skin
  28. persistent loss of appetite
  29. pinpoint red spots on the skin
  30. puffiness or swelling of the eyelids, or around the eyes, face, lips, or tongue
  31. redness, blistering, peeling, or loosening of the skin
  32. sensitivity to heat
  33. skin rash
  34. slowed heartbeat
  35. sudden loss of consciousness
  36. sweating
  37. swelling of the face, fingers, feet, or lower legs
  38. swelling of the mouth or throat
  39. tightness in the chest
  40. tightness in the throat
  41. upper right abdominal or stomach pain or tenderness
  42. weight gain or loss
  43. 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:

More common

  1. Heartburn
  2. indigestion
  3. sour stomach

Less common

  1. Hair loss
  2. 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.