Interferon-beta 1a

Reviewed on 6/24/2022

What Is Interferon-beta 1a and How Does It Work?

Interferon-beta 1a is a prescription medication used to treat the symptoms of Multiple Sclerosis.

  • Interferon-beta 1a is available under the following different brand names: Avonex, Rebif, Rebif Rebidose, AVOSTARTGRIP

What Are Side Effects Associated with Using Interferon beta 1a?

Common side effects of Interferon-beta 1a include:

  • injection site reactions (pain, swelling, or redness),
  • dizziness,
  • stomach pain, or
  • runny or stuffy nose.

Serious side effects of Interferon-beta 1a include:

  • hives,
  • difficulty breathing,
  • swelling of the face, lips, tongue, or throat,
  • severe skin reaction,
  • fever,
  • sore throat,
  • burning eyes,
  • skin pain,
  • red or purple skin rash with blistering and peeling,
  • pain, swelling, bruising, redness, oozing, or skin changes at the injection site,
  • light-headedness,
  • mood or behavior changes,
  • hopelessness,
  • anxiety, 
  • nervousness,
  • irritableness,
  • depression,
  • thoughts of self-harm,
  • easy bruising or bleeding,
  • seizure,
  • swelling,
  • rapid weight gain,
  • shortness of breath,
  • fast heartbeats,
  • chest pain spreading to the jaw or shoulder,
  • nausea,
  • sweating,
  • loss of appetite,
  • tiredness,
  • confusion,
  • dark urine,
  • clay-colored stools,
  • yellowing of the skin or eyes (jaundice),
  • chills,
  • cough with mucus,
  • bloody diarrhea,
  • pain or burning while urinating,
  • mood swings,
  • trouble sleeping,
  • diarrhea,
  • pounding heartbeats,
  • muscle weakness,
  • dry skin,
  • thinning hair,
  • menstrual changes,
  • weight changes,
  • puffiness in the face, and
  • feeling more sensitive to hot or cold temperatures

Rare side effects of Interferon-beta 1a include:

  • none 

This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Are Dosages of Interferon-beta 1a?

Adult and pediatric dosage

Prefilled IM syringe (Avonex)

  • 30mcg/0.5mL

Prefilled IM autoinjector pen (Avonex)

  • 30mcg/0.5mL

Powder for injection (Avonex)

  • 30mcg/vial (30mcg/0.5 mL reconstituted)

Prefilled SC syringes titration pack (Rebif)

  • 8.8mcg/0.2mL (6 syringes)
  • 22mcg/0.5mL (6 syringes)

Prefilled SC syringe (Rebif)

  • 22mcg/0.5mL
  • 44mcg/0.5mL

Prefilled SC autoinjector (Rebif Rebidose)

  • 8.8mcg/syringe
  • 22mcg/syringe
  • 44mcg/syringe

Multiple Sclerosis


Adult and geriatric dosage

  • 30 mcg Intramuscular every week
  • May be titrated using the AVOSTARTGRIP titration kit with prefilled Intramuscular syringes starting with 7.5 mcg Intramuscular for the first week, to reduce flu-like symptoms; increase by 7.5 mcg/week for the next 3 weeks until a recommended dose of 30 mcg/week

Rebif 44 mcg target dose

Adult and geriatric dosage 

  • Weeks 1-2: 8.8 mcg Subcutaneous 3 times/week (at least 48 hr apart)
  • Weeks 3-4: 22 mcg Subcutaneous 3 times/week
  • Weeks 5+: 44 mcg Subcutaneous 3 times/week

Rebif 22 mcg target dose

Adult and Geriatric dosage

  • Weeks 1-2: 4.4 mcg Subcutaneous 3 times/week (at least 48 hr apart)
  • Weeks 3-4: 11 mcg Subcutaneous 3 times/week
  • Weeks 5+: 22 mcg Subcutaneous 3 times/week

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Other Drugs Interact with Interferon beta 1a?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first

  • Interferon-beta 1a has severe interactions with no other drugs.
  • Interferon-beta 1a has serious interactions with the following drugs:
    • axicabtagene ciloleucel
    • brexucabtagene autoleucel
    • ciltacabtagene autoleucel
    • deferiprone
    • idecabtagene vicleucel
    • lisocabtagene maraleucel
    • pexidartinib
    • pretomanid
    • ropeginterferon alfa 2b
    • tisagenlecleucel
  • Interferon-beta 1a has moderate interactions with the following drugs:
  • Interferon-beta 1a has minor interactions with the following drug:
    • natalizumab

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Interferon beta 1a?


  • Hypersensitivity to beta interferons, albumin (for albumin-containing formulations)

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Interferon beta 1a?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Interferon beta 1a?”


  • Flu-like symptoms may occur
  • Efficacy in primary progressive MS not demonstrated conclusively; not recommended
  • Anaphylaxis is reported as a rare complication of therapy; other allergic reactions have included dyspnea, orolingual edema, skin rash, and urticaria; discontinue therapy if anaphylaxis or other allergic reactions occur
  • Decreased peripheral blood counts in all cell lines, including rare pancytopenia and thrombocytopenia, were reported from post-marketing experience in treated patients; in some cases, platelet counts were below10,000/microliter; some cases recurred with rechallenge; patients should be monitored for symptoms or signs of decreased blood counts
  • Cases of thrombotic microangiopathy (TMA), including thrombotic thrombocytopenic purpura and hemolytic uremic syndrome, some fatal, have been reported; cases have been reported several weeks to years after starting interferon beta products; discontinue therapy if clinical symptoms and laboratory findings consistent with TMA occur; manage as clinically indicated
  • Seizures have been temporally associated with the use of beta interferons in clinical trials and post-marketing safety surveillance; not known whether the events were related to the effects of multiple sclerosis alone, the drug, or a combination of both
  • Post-marketing reports of autoimmune disorders of multiple target organs in treated patients included idiopathic thrombocytopenia, hyper- and hypothyroidism, and rare cases of autoimmune hepatitis; if treated patients develop a new autoimmune disorder, consider stopping the therapy
  • In addition to laboratory tests normally required for monitoring patients with multiple sclerosis, complete blood and differential white blood cell counts, platelet counts, and blood chemistries, including liver function tests, are recommended during therapy; patients with myelosuppression may require more intensive monitoring of complete blood cell counts, with differential and platelet counts
  • Thyroid function should be monitored periodically If patients have or develop symptoms of thyroid dysfunction (hypo- or hyperthyroidism), thyroid function tests should be performed according to standard medical practice.

Depression and psychotic disorders

  • Patients treated with this drug and their caregivers should be advised to report immediately any symptoms of depression, suicidal ideation, and/or psychosis to their prescribing physicians; if a patient develops depression or other severe psychiatric symptoms, cessation of this therapy should be considered
  • There have been post-marketing reports of depression, suicidal ideation, and/or development of new or worsening other pre-existing psychiatric disorders, including psychosis; for some of these patients, symptoms of depression improved upon cessation of therapy

Hepatic injury

  • Severe hepatic injury, including cases of hepatic failure, has been reported rarely with this medication; asymptomatic elevation of hepatic transaminases has also been reported, and in some patients has recurred upon rechallenge with this drug; in some cases, these events have occurred in the presence of other drugs that have been associated with hepatic injury
  • The potential risk of this drug used in combination with known hepatotoxic drugs or other products (.g, alcohol) should be considered before starting therapy, or before starting hepatotoxic drugs; patients should be monitored for signs of hepatic injury

Congestive heart failure

  • Patients with pre-existing congestive heart failure should be monitored for worsening of their cardiac condition during initiation of and continued therapy
  • While beta interferons do not have any known direct cardiac toxicity, during the post-marketing period cases of congestive heart failure, cardiomyopathy, and cardiomyopathy with congestive heart failure have been reported in patients without known predisposition to these events, and without other etiologies being established
  • In some cases, these events have been temporally related to the administration of therapy; In some of these instances recurrence upon rechallenge was observed

Injection site reactions

  • Injection site reactions, including injection site necrosis, can occur with the use of interferon beta products; in controlled clinical trials, injection site reactions (.g, injection site pain, bruising, or erythema) were reported; reactions included injection site inflammation (6%), injection site pain (8%), injection site mass (below 1%), nonspecific reactions
  • Injection site abscesses and cellulitis and injection site necrosis were reported in the post-marketing setting with interferon beta products; some cases required treatment with hospitalization for surgical drainage and intravenous antibiotics
  • Periodically evaluate patient understanding and use of aseptic self-injection techniques and procedures, particularly if injection site necrosis has occurred
  • Whether to discontinue therapy following a single site of necrosis is dependent on the extent of necrosis; for patients who continue therapy after injection site necrosis has occurred, avoid administration of the drug into the affected area until it is fully healed; if multiple lesions occur, change injection site or discontinue therapy until healing occurs

Pregnancy & Lactation

  • Data from a large population-based cohort study, as well as other published studies over several decades, have not identified a drug-associated risk of major birth defects with use during early pregnancy
  • Findings regarding a potential risk for low birth weight or miscarriage with the use of interferon beta products in pregnancy have been inconsistent


  • Limited published literature has described the presence of interferon beta-1a products in human milk at low levels; there are no data on the effects of interferon-beta-1a on milk production
  • Therefore, the developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for therapy and any potential adverse effects on the breastfed infant from the drug or underlying maternal condition

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