Last updated on RxList: 10/15/2020
Extavia Side Effects Center

What Is Extavia?

Extavia (interferon beta-1b) Kit is made from human proteins and is used to treat relapsing multiple sclerosis (MS). Extavia will not cure MS, it will only decrease the frequency of relapse symptoms.

What Are Side Effects of Extavia?

Common side effects of Extavia include:

  • headache,
  • muscle pain or weakness,
  • sleep problems (insomnia),
  • stomach or abdominal pain,
  • swelling in your hands or feet,
  • skin rash,
  • hives,
  • itching,
  • irregular menstrual periods,
  • flu-like symptoms (chills, fever, general feeling of being unwell),
  • increased sweating,
  • decreased white blood cell count,
  • injection site reactions (bruising, swelling, redness, pain, warm feeling, or leaking of fluid),
  • stuffy nose, or
  • irregular heartbeat

Dosage for Extavia

The recommended dose of Extavia is 0.25 mg injected subcutaneously every other day.

What Drugs, Substances, or Supplements Interact with Extavia?

Extavia may interact with other drugs. Tell your doctor all medications and supplements you use.

Extavia During Pregnancy and Breastfeeding

Do not use Extavia if you are pregnant. It may be harmful to a fetus, or may cause a miscarriage. Tell your doctor if you become pregnant during treatment. It is unknown if this drug passes into breast milk or if it could harm a nursing baby. Consult your doctor before breastfeeding.

Additional Information

Our Extavia (interferon beta-1b) Kit Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


What Is Multiple Sclerosis? MS Symptoms, Causes, Diagnosis See Slideshow
Extavia Consumer Information

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Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Some patients using interferon medicines have become very depressed or had thoughts of suicide. Report any new or worsening symptoms of depression to your doctor, such as: mood or behavior changes, anxiety, trouble sleeping, hallucinations, or if you feel impulsive, hostile, aggressive, depressed, or have thoughts about suicide or hurting yourself.

Stop using interferon beta-1b and call your doctor at once if you have:

  • fever, chills, sweating, tiredness, body aches;
  • a seizure;
  • pain, swelling, redness, or skin changes where an injection was given;
  • heart problems--chest tightness, swelling, rapid weight gain, trouble lying flat in bed, feeling short of breath;
  • liver problems--nausea, vomiting, itching, easy bruising, unusual bleeding, dark urine, jaundice (yellowing of your skin or eyes); or
  • new or worsening symptoms of lupus--joint pain, and a skin rash on your cheeks or arms that worsens in sunlight.

Common side effects may include:

  • low white blood cell counts;
  • abnormal liver function tests;
  • headache, weakness;
  • sleep problems (insomnia);
  • stomach pain;
  • muscle pain, stiffness, or weakness;
  • rash;
  • flu symptoms; or
  • a skin reaction where the medicine was injected.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Extavia (Interferon Beta-1b Kit)


What kind of disease is multiple sclerosis? See Answer
Extavia Professional Information


The following serious adverse reactions are discussed in more details in other sections of labeling:

  • Hepatic Injury [see WARNINGS AND PRECAUTIONS]
  • Anaphylaxis and Other Allergic Reactions [see WARNINGS AND PRECAUTIONS]
  • Depression and Suicide [see WARNINGS AND PRECAUTIONS]
  • Congestive Heart Failure [see WARNINGS AND PRECAUTIONS]
  • Injection Site Necrosis and Reactions [see WARNINGS AND PRECAUTIONS]
  • Thrombotic Microangiopathy [see WARNINGS AND PRECAUTIONS]
  • Flu-like Symptom Complex [see WARNINGS AND PRECAUTIONS]
  • Drug-induced Lupus Erythematosus [see WARNINGS AND PRECAUTIONS]

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions and over varying lengths of time, adverse reaction rates observed in the clinical trials of interferon beta-1b cannot be directly compared to rates in clinical trials of other drugs, and may not reflect the rates observed in practice.

Among 1407 patients with MS treated with interferon beta-1b 0.25 mg every other day (including 1261 patients treated for greater than one year), the most commonly reported adverse reactions (at least 5% more frequent on interferon beta-1b than on placebo) were injection site reaction, lymphopenia, flu-like symptoms, myalgia, leukopenia, neutropenia, increased liver enzymes, headache, hypertonia, pain, rash, insomnia, abdominal pain, and asthenia. The most frequently reported adverse reactions resulting in clinical intervention (for example, discontinuation of interferon beta-1b, adjustment in dosage, or the need for concomitant medication to treat an adverse reaction symptom) were depression, flu-like symptom complex, injection site reactions, leukopenia, increased liver enzymes, asthenia, hypertonia, and myasthenia.

Table 2 enumerates adverse reactions and laboratory abnormalities that occurred among patients treated with 0.25 mg of interferon beta-1b every other day by subcutaneous injection in the pooled placebo-controlled trials (Study 1-4) at an incidence that was at least 2% more than that observed in the placebo-treated patients [see Clinical Studies].

Table 2: Adverse Reactions and Laboratory Abnormalities in Patients with MS in Pooled Studies 1, 2, 3, and 4

Adverse ReactionPlacebo
(N = 965)
Interferon beta-1b
(N = 1407)
Blood and lymphatic system disorders
Lymphocytes count decreased (< 1500/mm3)66%86%
Absolute neutrophil count decreased (< 1500/mm3)5%13%
White blood cell count decreased (< 3000/mm3)4%13%
Nervous system disorders
Vascular disorders
Respiratory, thoracic, and mediastinal disorders
Gastrointestinal disorders
Abdominal pain11%16%
Hepatobiliary disorders
Alanine aminotransferase increased (SGPT > 5 times baseline)4%12%
Aspartate aminotransferase increased (SGOT > 5 times baseline)1%4%
Skin and subcutaneous tissue disorders
Skin disorder8%10%
Musculoskeletal and connective tissue disorders
Renal and urinary disorders
Urinary urgency8%11%
Reproductive system and breast disorders
General disorders and administration-site conditions
Injection site reactiona26%78%
Flu-like symptoms (complex)b37%57%
Peripheral edema10%12%
Chest pain6%9%
Injection site necrosis0%4%
a"Injection site reaction" comprises all adverse reactions occurring at the injection site (except injection site necrosis), that is, the following terms: injection site reaction, injection site hemorrhage, injection site hypersensitivity, injection site inflammation, injection site mass, injection site pain, injection site edema and injection site atrophy.
b"Flu-like symptom (complex)" denotes flu syndrome and/or a combination of at least two adverse reactions from fever, chills, myalgia, malaise, sweating.

In addition to the adverse reactions listed in Table 2, the following adverse reactions occurred more frequently on interferon beta-1b than on placebo, but with a difference smaller than 2%: alopecia, anxiety, arthralgia, constipation, diarrhea, dizziness, dyspepsia, dysmenorrhea, leg cramps, menorrhagia, myasthenia, nausea, nervousness, palpitations, peripheral vascular disorder, prostatic disorder, tachycardia, urinary frequency, vasodilatation, and weight increase.

Laboratory Abnormalities

In the four clinical trials (Studies 1, 2, 3, and 4), leukopenia was reported in 18% and 6% of patients in interferon beta-1band placebo-treated groups, respectively. No patients were withdrawn or dose-reduced for neutropenia in Study 1. Three percent (3%) of patients in Studies 2 and 3 experienced leukopenia and were dose-reduced. Other abnormalities included increase of SGPT to greater than five times baseline value (12%), and increase of SGOT to greater than five times baseline value (4%). In Study 1, two patients were dose-reduced for increased hepatic enzymes; one continued on treatment and one was ultimately withdrawn. In Studies 2 and 3, 1.5% of interferon beta-1b patients were dose-reduced or interrupted treatment for increased hepatic enzymes. In Study 4, 1.7% of patients were withdrawn from treatment due to increased hepatic enzymes, two of them after a dose reduction. In Studies 1-4, nine (0.6%) patients were withdrawn from treatment with interferon beta-1b for any laboratory abnormality, including four (0.3%) patients following dose reduction.


As with all therapeutic proteins, there is a potential for immunogenicity. Serum samples were monitored for the development of antibodies to interferon beta-1b during Study 1. In patients receiving 0.25 mg every other day 56/124 (45%) were found to have serum neutralizing activity at one or more of the time points tested. In Study 4, neutralizing activity was measured every 6 months and at end of study. At individual visits after start of therapy, activity was observed in 17% up to 25% of the interferon beta-1b-treated patients. Such neutralizing activity was measured at least once in 75 (30%) out of 251 interferon beta-1b patients who provided samples during treatment phase; of these, 17 (23%) converted to negative status later in the study. Based on all the available evidence, the relationship between antibody formation and clinical safety or efficacy is not known.

These data reflect the percentage of patients whose test results were considered positive for antibodies to interferon beta1b using a biological neutralization assay that measures the ability of immune sera to inhibit the production of the interferon-inducible protein, MxA. Neutralization assays are highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of neutralizing activity in an assay may be influenced by several factors including sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to interferon beta-1b with the incidence of antibodies to other products may be misleading.

Anaphylactic reactions have been reported with the use of interferon beta-1b [see WARNINGS AND PRECAUTIONS].

Postmarketing Experience

The following adverse reactions have been identified during postapproval use of interferon beta-1b. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Blood and lymphatic system disorders: Anemia, Thrombocytopenia, Hemolytic anemia

Endocrine disorders: Hypothyroidism, Hyperthyroidism, Thyroid dysfunction

Metabolism and nutrition disorders: Triglyceride increased, Anorexia, Weight decrease, Weight increase

Psychiatric disorders: Anxiety, Confusion, Emotional lability

Nervous system disorders: Convulsion, Dizziness, Psychotic symptoms

Cardiac disorders: Cardiomyopathy, Palpitations, Tachycardia

Vascular disorders: Vasodilatation

Respiratory, thoracic, and mediastinal disorders: Bronchospasm

Gastrointestinal disorders: Diarrhea, Nausea, Pancreatitis, Vomiting

Hepatobiliary disorders: Hepatitis, Gamma GT increased

Skin and subcutaneous tissue disorders: Alopecia, Pruritus, Skin discoloration, Urticaria

Musculoskeletal and connective tissue disorders: Arthralgia, Drug-induced lupus erythematosus

Reproductive system and breast disorder: Menorrhagia

General disorders and administration site conditions: Fatal capillary leak syndrome*

*The administration of cytokines to patients with a preexisting monoclonal gammopathy has been associated with the development of this syndrome.

Read the entire FDA prescribing information for Extavia (Interferon Beta-1b Kit)

© Extavia Patient Information is supplied by Cerner Multum, Inc. and Extavia Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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