Interferon Beta-1a Intramuscular Injection


Interferon beta-1a intramuscular injection is used to treat adults with various forms of multiple sclerosis (MS; a disease in which the nerves do not function properly and people may experience weakness, numbness, loss of muscle coordination, and problems with vision, speech, and bladder control) including:

  • clinically isolated syndrome (CIS; nerve symptom episodes that last at least 24 hours),
  • relapsing-remitting forms (course of disease where symptoms flare up from time to time), or
  • secondary progressive forms (course of disease where relapses occur more often).

Interferon beta-1a is in a class of medications called immunomodulators. It works by decreasing inflammation and preventing nerve damage that may cause symptoms of multiple sclerosis.

Side Effects Of Interferon Beta-1a Intramuscular Injection

Interferon beta-1a may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • tight muscles
  • dizziness
  • numbness, burning, tingling, or pain in hands or feet
  • joint pain
  • eye problems
  • runny nose
  • toothache
  • hair loss
  • bruising, pain, redness, swelling, bleeding, or irritation at the injection spot

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately or get emergency medical treatment:

  • new or worsening depression
  • thinking about harming or killing yourself or planning or trying to do so
  • feeling very emotional
  • hallucinating (seeing things or hearing voices that do not exist)
  • seizures
  • unexplained weight gain or loss
  • feeling cold or hot all the time
  • trouble breathing when lying flat in bed
  • increased need to urinate during the night
  • painful or difficult urination
  • decreased ability to exercise
  • chest pain or tightness
  • fast or irregular heartbeat
  • pale skin
  • excessive tiredness
  • lack of energy
  • loss of appetite
  • unusual bleeding or bruising
  • pain or swelling in the upper right part of the stomach
  • yellowing of the skin or eyes
  • dark brown urine
  • light-colored bowel movements
  • sore throat, cough, or other signs of infection
  • hives
  • rash
  • itching
  • swelling of the face, throat, tongue, lips, eyes, hands, arms, feet, ankles, or lower legs
  • difficulty breathing or swallowing
  • hoarseness
  • flushing
  • red or bloody stools or diarrhea
  • stomach pain
  • slow or difficult speech
  • purple patches or pinpoint dots (rash) on the skin
  • decreased urination or blood in the urine

Interferon beta-1a may cause other side effects. Call your doctor if you have any unusual problems while using this medication.

Warnings & Precautions

Before using interferon beta-1a:

  • tell your doctor and pharmacist if you are allergic to interferon beta-1a, any other interferon medications (Betaseron, Extavia, Plegridy, Rebif), any other medications, human albumin, natural rubber, latex, or any of the ingredients in interferon beta-1a intramuscular injection. Ask your pharmacist or check the Medication Guide for a list of the ingredients.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • tell your doctor if you drink or have ever drunk large amounts of alcohol and if you have or have ever had an autoimmune disease other than MS (a disease in which the body attacks its own cells; ask your doctor if you are unsure if you have this type of disease); blood problems such as anemia (red blood cells that do not bring enough oxygen to all parts of the body), low white blood cells, or easy bruising or bleeding; a mental illness such as depression, especially if you have ever thought about killing yourself or tried to do so; other mood disorders or mental illness; seizures; or heart, liver, or thyroid disease.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while using interferon beta-1a, call your doctor immediately.
  • if you are having surgery, including dental surgery, tell the doctor or dentist that you are using interferon beta-1a.
  • ask your doctor about the safe use of alcoholic beverages while you are using interferon beta-1a. Alcohol can increase the risk that you will develop serious side effects from interferon beta-1a.
  • you should know that you may have flu-like symptoms such as headache, fever, chills, sweating, muscle aches, nausea, vomiting, and tiredness that last for a day after your injection. Your doctor may tell you to inject your medication at bedtime and take an over-the-counter pain and fever medication to help with these symptoms. These symptoms usually lessen or go away over time. Talk to your doctor if these symptoms are difficult to manage or become severe.

Dosage Of Interferon Beta-1a Intramuscular Injection

Interferon beta-1a intramuscular injection comes as a powder in vials to be mixed into a solution for injection. Interferon beta-1a intramuscular injection also comes as a solution (liquid) in prefilled injection syringes and in a prefilled automatic injection pen. This medication is injected into a muscle, usually once a week, on the same day each week. Inject interferon beta-1a intramuscular at around the same time of day on your injection days. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Use interferon beta-1a exactly as directed. Do not use more or less of it or use it more often than prescribed by your doctor.

Interferon beta-1a controls the symptoms of MS but does not cure it. Continue to use interferon beta-1a even if you feel well. Do not stop using interferon beta-1a without talking to your doctor.

You will receive your first dose of interferon beta-1a intramuscular in your doctor’s office. After that, you can inject interferon beta-1a intramuscular yourself or have a friend or relative perform the injections. Ask your doctor or pharmacist to show you or the person who will be injecting the medication how to inject it. Before you use interferon beta-1a intramuscular for the first time, you or the person who will be giving the injections should also read the manufacturer’s information for the patient that comes with it. Follow the directions carefully.

Be sure you know what type of container your interferon beta 1b comes in and what other supplies, such as needles or syringes, you will need to inject your medication. If your interferon beta 1b intramuscular comes in vials, you will need to use a syringe and needle to inject your dose.

Always use a new, unopened vial, prefilled syringe, and needle, or prefilled automatic injection pen for each injection. Never reuse vials, syringes, needles, or automatic injection pens. Discard used syringes, needles, and injection pens in a puncture-resistant container kept out of reach of children. Talk to your doctor or pharmacist about how to discard the puncture-resistant container.

Always look at the medication in your vial, prefilled syringe, or automatic injection pen before you use it. If you are using a vial, the solution in the vial should be clear to slightly yellow after mixing. If you are using a prefilled syringe or automatic injection pen, the solution should be clear and colorless. If the solution is cloudy, discolored, or contains particles or if the expiration date marked on the vial, prefilled syringe, or automatic injection pen has passed, do not use that vial, prefilled syringe, or automatic injection pen.

Talk to your doctor or pharmacist about where on your body you should inject interferon beta-1a intramuscular. If you are using a syringe or prefilled syringe, you can inject interferon beta-1a intramuscular in your upper arms or thighs. If you are using a prefilled autoinjection pen, you can inject interferon beta-1a intramuscular in the outer surface of your upper thighs. Use a different spot for each injection. Do not use the same spot two times in a row. Do not inject into an area where the skin is sore, red, bruised, scarred, infected, irritated, or abnormal in any way.

Your doctor or pharmacist will give you the manufacturer’s patient information sheet (Medication guide) when you begin treatment with interferon beta-1a and each time you refill your prescription.


Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your body’s response to interferon beta-1a.

Do not let anyone else use your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.