Instructions for Use
800.456.2255

AVONEX adverse reactions1

The table below shows adverse reactions reported at an incidence of at least 2% greater frequency in AVONEX-treated patients than placebo-treated patients in placebo-controlled clinical trials.

Adverse reactions occurring ≥2% more frequently on AVONEX vs placebo1

Adverse reaction AVONEX n=351
%		 Placebo n=333
%
Body as a Whole
Headache5855
Flu-like symptoms4929
Pain2321
Asthenia2418
Fever209
Chills195
Abdominal pain86
Injection site pain86
Infection74
Injection site inflammation62
Chest pain52
Injection site reaction31
Toothache31
Nervous System
Depression1814
Dizziness1412
Respiratory System
Upper respiratory tract infection1412
Sinusitis1412
Bronchitis85
Digestive System
Nausea2319
Musculoskeletal System
Myalgia2922
Arthralgia96
Urogenital
Urinary tract infection1715
Urine constituents abnormal30
Skin and Appendages
Alopecia42
Special Senses
Eye disorder42
Hemic and Lymphatic System
Injection site ecchymosis64
Anemia41
Cardiovascular System
Migraine53
Vasodilation20
Get Started

Get your patients started on therapy and enrolled in Biogen Support Services with the AVONEX Start Form.

E-Sign Start Form

Download Start Form
One injection, once a week1

Explore once-a-week dosing and different dosage forms for your patients with relapsing MS

Review AVONEX dosing
AVONEX efficacy

Results in 3 key measures of relapsing MS disease activity

See AVONEX efficacy
Next: Managing Common Side Effects

Indication

AVONEX® (interferon beta-1a) is indicated for the treatment of relapsing forms of multiple sclerosis (MS), to include clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease, in adults.

Important Safety Information

CONTRAINDICATIONS

  • AVONEX® (interferon beta-1a) is contraindicated in patients with a history of hypersensitivity to natural or recombinant interferon beta, or any other component of the formulation
  • The formerly available lyophilized vial formulation of AVONEX is contraindicated in patients with a history of hypersensitivity to albumin (human)

WARNINGS AND PRECAUTIONS

Depression, Suicide, and Psychotic Disorders

  • Patients treated with AVONEX and their caregivers should be advised to report immediately any symptoms of depression, suicidal ideation, and/or psychosis to their prescribing physician. If a patient develops depression or other severe psychiatric symptoms, cessation of AVONEX therapy should be considered. Depression and suicide have been reported to occur with increased frequency in patients receiving AVONEX. Additionally, there have been postmarketing reports of depression, suicidal ideation, and/or development of new or worsening of other pre-existing psychiatric disorders, including psychosis. For some of these patients, symptoms of depression improved upon cessation of AVONEX

Hepatic Injury

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

Anaphylaxis and Other Allergic-Reactions

  • Anaphylaxis has been reported as a rare complication of AVONEX use. Other allergic reactions have included dyspnea, orolingual edema, skin rash and urticaria. Discontinue AVONEX if anaphylaxis or other allergic reactions occur

Injection Site Reactions Including Necrosis

  • Injection site reactions, including injection site necrosis, can occur with the use of interferon beta products, including AVONEX. In controlled clinical trials, injection site reactions (e.g., injection site pain, bruising or erythema) occurred in 18% of patients receiving AVONEX and 13% in the placebo group. These reactions included injection site inflammation (6%), injection site pain (8%), injection site mass (<1%), nonspecific reactions. Injection site abscesses and cellulitis and injection site necrosis have been reported in the postmarketing setting with interferon beta products, including AVONEX. 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 with AVONEX after injection site necrosis has occurred, avoid administration of AVONEX into the affected area until it is fully healed. If multiple lesions occur, change injection site or discontinue therapy until healing occurs

Congestive Heart Failure

  • Patients with pre-existing congestive heart failure should be monitored for worsening of their cardiac condition during initiation of and continued treatment with AVONEX. While beta interferons do not have any known direct cardiac toxicity, during the postmarketing 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

Decreased Peripheral Blood Counts

  • Decreased peripheral blood counts in all cell lines, including rare pancytopenia and thrombocytopenia, have been reported from postmarketing experience in AVONEX-treated patients

Thrombotic Microangiopathy

  • Cases of thrombotic microangiopathy (TMA), including thrombotic thrombocytopenic purpura and hemolytic uremic syndrome, some fatal, have been reported with interferon beta products, including AVONEX. Cases have been reported several weeks to years after starting interferon beta products. Discontinue AVONEX if clinical symptoms and laboratory findings consistent with TMA occur, and manage as clinically indicated

Pulmonary Arterial Hypertension

  • Cases of pulmonary arterial hypertension (PAH) have been reported in patients treated with interferon beta products, including AVONEX. PAH has occurred in patients treated with interferon beta products in the absence of other contributory factors. Many of the reported cases required hospitalization, including one case with interferon beta in which the patient underwent a lung transplant. PAH has developed at various time points after initiating therapy with interferon beta products and may occur several years after starting treatment. Patients who develop unexplained symptoms (e.g., dyspnea, new or increasing fatigue) should be assessed for PAH. If alternative etiologies have been ruled out and a diagnosis of PAH is confirmed, discontinue treatment and manage as clinically indicated

Seizures

  • Seizures have been temporally associated with the use of beta interferons in clinical trials and postmarketing safety surveillance. It is not known whether these events were related to the effects of multiple sclerosis alone, to AVONEX, or to a combination of both

Autoimmune Disorders

  • Postmarketing reports of autoimmune disorders of multiple target organs in AVONEX-treated patients included idiopathic thrombocytopenia, hyper- and hypothyroidism, and rare cases of autoimmune hepatitis. If AVONEX-treated patients develop a new autoimmune disorder, consider stopping the therapy

Laboratory Tests

  • In addition to those 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 AVONEX 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

MOST COMMON SIDE EFFECTS

  • The most commonly reported adverse reactions (at least 5% more frequent on AVONEX than on placebo) were flu-like symptoms. Symptoms can include chills, fever, myalgia and asthenia occurring within hours to days following an injection. The most frequently reported adverse reactions resulting in clinical intervention were flu-like symptoms and depression

Reference: 1. AVONEX Prescribing Information. Cambridge, MA: Biogen.

Start AVONEX
Getting started Dosing Support program
Efficacy
AVONEX efficacy Pivotal trials Long-term follow-up studies
Safety
Well-understood safety profile Adverse reactions Managing common side effects Special populations
Access and reimbursement
Access and
reimbursement

©2025 Biogen. All rights reserved. AVX-US-0587​ ​​v9 02/25
All trademarks are the property of their respective owners.
For US healthcare professionals only.