Avonex: Indications, Ways of Use, Side Effects and Interactions

It belongs to a group of drugs called immunomodulators, which are believed to help limit the destruction of the protective myelin layer of nerve fibers.

Avonex (interferon beta-1a) is a prescription drug used to treat multiple sclerosis .

Avonex comes in liquid form in prefilled syringes or single-use vials that come with sterile water for mixing. It should be injected directly into the muscle once a week, or just under the skin (subcutaneous or sub Q) 3 times a week, depending on the form you receive.

Common side effects of Avonex include headache, flu-like symptoms, and fever.


Interferon beta-1a belongs to a group of drugs known as immunomodulators. It is a form of a protein that is produced naturally by the cells of our body to fight infections and tumors.

Interferon beta-1a is used to treat recurrent forms of multiple sclerosis (MS), a chronic, disabling disease that affects the central nervous system by destroying the protective covering (myelin) that surrounds nerve fibers.

This drug is also used to delay the onset of MS in people who have experienced a single flare of symptoms and have changes that suggest MS on their magnetic resonance imaging (MRI).

Avonex will not cure multiple sclerosis, but it may decrease the number of disease flare-ups, slow the progression of disability, and decrease the number and volume of active brain lesions (damaged areas of the brain) seen on MRI scans.

This medicine can also be used to treat people with another type of MS known as secondary progressive MS (SPMS) who still have relapses. For people with SPMS, medication can decrease the frequency of relapses and reduce brain lesions seen on MRI scans.

Ways of use

Avonex PS

Each sterile liquid pre-filled syringe contains interferon beta-1a 30 μg (6.0 million IU). Non-Medicinal Ingredients: USP Arginine Hydrochloride, USP Glacial Acetic Acid, Polysorbate 20, USP Sodium Acetate Trihydrate, and USP Water for Injections 0.5 ml at pH 4.8.

Avonex Pen

Each single-use prefilled sterile liquid autoinjector contains interferon beta-1a 30 μg (6.0 million IU). Non-Medicinal Ingredients: USP Arginine Hydrochloride, USP Glacial Acetic Acid, Polysorbate 20, USP Sodium Acetate Trihydrate, and USP Water for Injections 0.5 ml at pH 4.8.

How should I use this medicine?

The usual adult dose of interferon beta-1a for people with recurrent forms of MS is 30 μg once a week as an injection into a muscle (thigh or arm) on the same day of the week (for example, every Saturday just before bedtime).

For people with relapsing progressive MS or secondary progressive MS with recurring attacks, your doctor may increase the dose to 60 μg once a week.

To reduce flu-like symptoms at the beginning of treatment, your doctor may start treatment with a lower dose and gradually increase the dose weekly over three to six weeks.

Interferon beta-1a is used with the guidance and supervision of a doctor. Your doctor or nurse may ask you to inject the medicine at home once they have instructed you and are sure you will have no problem doing it at home.

Do not try to prepare or inject this medicine on your own until you fully understand how to prepare the syringe and inject a dose.

Make sure to change your injection site every week. You should avoid injecting this medicine into an area of ​​the skin that is sore, red, infected, or otherwise damaged. If you have trouble giving yourself injections, talk to your healthcare provider.

Prefilled syringes of interferon beta-1a should be stored in the refrigerator. Remove the syringe from the refrigerator about 30 minutes before use to allow the medicine to reach room temperature.

Do not use external heat sources (such as hot water or a microwave) to heat the medicine. The pre-filled syringe should be used within 7 days of removing it from the refrigerator.

See the package leaflet for full instructions on the use of this medicine. Always wash your hands before preparing the medicine and after using it. Always use a new, unopened vial, syringe, and needle.

Protect this medicine from light, moisture, freezing, and high temperatures.

Side effects

  • Abdominal pain.
  • Decreased appetite.
  • Diarrhea.
  • Difficulty to sleep.
  • Dizziness.
  • Flu-like symptoms (fever, chills).
  • Hair loss.
  • Headache.
  • Acidity.
  • Muscle pains.
  • Nausea.
  • Skin irritation, swelling, or pain at the injection site.
  • Tiredness or weakness

Although most of the side effects listed below don’t happen very often, they could lead to serious problems if you don’t seek medical attention.

Check with your doctor as soon as possible if you experience any of the following side effects:

  • Chills or fever
  • Impaired hearing
  • Fainting.
  • Difficulty breathing.
  • Signs of anemia (low levels of red blood cells, eg dizziness, pale skin, unusual tiredness or weakness, shortness of breath).
  • Signs of bleeding (low platelet levels, eg bloody nose, blood in urine, blood when coughing up, bleeding gums, cuts that won’t stop bleeding).
  • Signs of depression (for example, poor concentration, weight changes, sleep changes, decreased interest in activities, thoughts of suicide).
  • Signs of infection (decreased number of white blood cells, for example fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss or listlessness)
  • Signs of heart problems (eg, decreased ability to exercise, increased heart rate, shortness of breath, ankle swelling, chest tightness).
  • Signs of liver problems (for example, abdominal pain, dark urine or pale stools, easy bruising, yellow eyes, or skin).
  • Signs of thyroid problems.

What other drugs could interact with this medicine?

  • Medicines that can affect the immune system (eg, corticosteroids, chemotherapy).
  • Theophylline
  • Vaccines.
  • Zidovudine.