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Avonex

Generic Name: interferon beta-1a (in ter FEAR on BAY ta)
Brand Names: Avonex
Avonex is an interferon used in the treatment of relapsing multiple sclerosis. Learn about side effects, interactions and indications.
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Drug Information:
Avonex (interferon beta-1a) is made from human proteins. Interferons help the body fight viral infections. Avonex is used to treat relapsing multiple sclerosis (MS) in adults. Avonex will not cure MS, it will only decrease the frequency of relapse symptoms. Avonex can harm your liver. Call your doctor if you have symptoms such as nausea, loss of appetite, tiredness, confusion, easy bruising or bleeding, dark urine, clay-colored stools, or yellowing of your skin or eyes. Some people have thoughts about suicide while using interferon beta-1a. Stay alert to changes in your mood or symptoms. Report any new or worsening symptoms to your doctor. Learn more

Avonex Side Effects

Avonex Side Effects

Note: This document contains side effect information about interferon beta-1a. Some of the dosage forms listed on this page may not apply to the brand name Avonex.

In Summary

Common side effects of Avonex include: flu-like symptoms, fever, headache, myalgia, nausea, and chills. Other side effects include: anemia. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to interferon beta-1a: kit, solution

Along with its needed effects, interferon beta-1a (the active ingredient contained in Avonex) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking interferon beta-1a:

More common

  • Black, tarry stools
  • chest pain
  • chills
  • cough
  • diarrhea
  • fever
  • flu-like symptoms
  • headache
  • joint pain
  • muscle aches
  • nausea
  • pain
  • painful or difficult urination
  • shortness of breath
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen glands
  • unusual bleeding or bruising
  • unusual tiredness or weakness

Less common

  • Abdominal or stomach pain
  • clumsiness or unsteadiness
  • convulsions (seizures)
  • decreased hearing
  • difficulty with swallowing
  • dizziness
  • fainting
  • feeling of warmth
  • hives or itching
  • mood changes, especially with thoughts of suicide
  • muscle spasms
  • pain or discharge from the vagina
  • pelvic discomfort, aching, or heaviness
  • redness of the face, neck, arms, and occasionally, upper chest
  • redness, swelling, or tenderness at the injection site
  • runny or stuffy nose
  • skin lesions
  • sneezing
  • sore throat
  • speech problems
  • swelling of the face, lips, or eyelids
  • troubled breathing

Rare

  • Earache
  • general feeling of discomfort or illness
  • loss of appetite
  • painful blisters on trunk of the body
  • painful cold sores or blisters on the lips, nose, eyes, or genitals

Incidence not known

  • Bleeding gums
  • blood in the urine or stools
  • bloody nose
  • chest discomfort
  • confusion
  • constipation
  • dark urine
  • decreased urine output
  • depressed mood
  • dilated neck veins
  • dry skin and hair
  • extreme fatigue
  • fast, irregular, or pounding heartbeat
  • feeling cold
  • general tiredness and weakness
  • hair loss
  • heavier menstrual periods
  • high fever
  • irregular breathing
  • light-colored stools
  • loss of bladder control
  • mental depression
  • mood or other mental changes
  • muscle cramps and stiffness
  • nausea or vomiting
  • nervousness
  • pale skin
  • persistent loss of appetite
  • pinpoint red spots on the skin
  • puffiness or swelling of the eyelids, or around the eyes, face, lips, or tongue
  • redness, blistering, peeling, or loosening of the skin
  • sensitivity to heat
  • skin rash
  • slowed heartbeat
  • sudden loss of consciousness
  • sweating
  • swelling of the face, fingers, feet, or lower legs
  • swelling of the mouth or throat
  • tightness in the chest
  • tightness in the throat
  • upper right abdominal or stomach pain or tenderness
  • weight gain or loss
  • yellow eyes and skin

Some side effects of interferon beta-1a may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Heartburn
  • indigestion
  • sour stomach

Less common

  • Hair loss
  • trouble sleeping

For Healthcare Professionals

Applies to interferon beta-1a: intramuscular kit, intramuscular powder for injection, subcutaneous kit, subcutaneous solution

General

Influenza-like symptoms (e.g., myalgia, fever, chills, sweating, asthenia, headache, nausea) are the most common adverse reactions.

Hematologic

Very common (10% or more): Lymphopenia (14%), leukopenia (11%), neutropenia, thrombocytopenia, anemia

Common (1% to 10%): Neutrophil count decreased, hematocrit decreased, blood potassium increased, blood urea nitrogen increased

Uncommon (0.1% to 1%): Platelet count decreased

Rare (Less than 0.1%): Thrombotic microangiopathy including thrombotic thrombocytopenic purpura/hemolytic uremic syndrome,

Frequency not reported: Pancytopenia

Gastrointestinal

Very common (10% or more): Nausea (27%), diarrhea (17%), constipation (12%), vomiting (10%)

Common (1% to 10%): Abdominal pain, toothache

Frequency not reported: Dry mouth, dyspepsia

Dermatologic

Very common (10% or more): Skin rashes (25%), increased sweating

Common (1% to 10%): Contusion, pruritus, erythematous rash, maculopapular rash, night sweats

Uncommon (0.1% to 1%): Alopecia, allergic dermatitis, erythema, urticaria

Rare (0.01% to 0.1%): Skin ulceration/necrosis at the site of injection, Quincke's edema (angioedema), erythema multiforme, Stevens-Johnson syndrome

Very rare (less than 0.01%): Calcified subcutaneous nodules, psoriasis, periungual and nail alterations

Frequency not reported: Rash vesicular

Endocrine

Uncommon (0.1% to 1%): Hypothyroidism, hyperthyroidism

Cardiovascular

Frequency not reported: Cardiomyopathy, congestive heart failure, palpitations, arrhythmia, tachycardia, vasodilatation, chest pain, pulmonary arterial hypertension (PAH) (sometimes reported up to several years after starting treatment)

Genitourinary

Very common (10% or more): Urinary tract infection (19%), cystitis (11%)

Frequency not reported: Metrorrhagia, menorrhagia, urinary incontinence, increase in the frequency of micturition

Hepatic

Very common (10% or more): Alanine aminotransferase increased (26%), aspartate aminotransferase increased (16%)

Common (1% to 10%): Gamma-glutamyl-transferase increased

Uncommon (0.1% to 1%): Hepatitis (with or without icterus)

Rare (Less than 0.1%): Hepatic failure, autoimmune hepatitis

Frequency not reported: Elevation of hepatic transaminases (SGPT and SGOT), bilirubinemia, jaundice

Hypersensitivity

Rare (Less than 0.1%): Anaphylactic reactions

Frequency not reported: Other allergic reactions

Immunologic

Very common (10% or more): Influenza-like symptoms (49%)

Frequency not reported: Systemic lupus erythematosus, anaphylactic reaction, anaphylactic shock, hypersensitivity reactions (angioedema, dyspnea, urticaria, rash, pruritic rash)

Local

Very common (10% or more): Injection site erythema (62%), injection site pain (15%), injection site pruritus (13%), injection site bruising

Common (1% to 10%): Injection site edema, injection site warmth, injection site hematoma, injection site rash

Uncommon (0.1% to 1%): Injection site infections (which could be severe)

Rare (Less than 0.1%): Injection site cellulitis (which could be severe)

Frequency not reported: Injection site abscess, injection site reaction, injection site inflammation, injection site necrosis, injection site bleeding

Musculoskeletal

Very common (10% or more): Myalgia (19%), back pain (20%), pain in extremity (19%), arthralgia (16%), muscular weakness (12%), muscle spasms (10%)

Common (1% to 10%): Muscle spasticity, muscle cramp, neck pain, arthralgia, muscle stiffness, musculoskeletal stiffness

Rare (0.01% to 0.1%): Drug induced lupus erythematosus

Frequency not reported: Arthritis

Nervous system

Very common (10% or more): Headache (67%), dizziness (16%), paresthesia (12%)

Common (1% to 10%): Hypoesthesia

Uncommon (0.1% to 1%): Facial hypoesthesia

Frequency not reported: Neurological symptoms, syncope, hypertonia, seizures, migraine

Metabolic

Frequency not reported: Weight decreased, weight increased

Ocular

Common (1% to 10%): Eye pain

Uncommon (0.1% to 1%): Retinal vascular disorders (i.e. retinopathy, cotton wool spots, obstruction of retinal artery or vein)

Frequency not reported: Eye disorder, abnormal vision, xerophthalmia

Other

Very common (10% or more): Pyrexia (45%), asthenia (24%), pain (23%), fever (20%), chills (19%)

Common (1% to 10%): Fatigue, malaise, hyperthermia, vertigo

Frequency not reported: Tachyphylaxis, sudden hearing loss, tinnitus (ototoxic effects resolved 7 to 14 days after discontinuation of the drug)

Psychiatric

Common (1% to 10%): Depression/suicidal ideation, insomnia, somnolence

Uncommon (0.1% to 1%): Anxiety

Frequency not reported: Suicide attempt, suicide, psychosis, anxiety, confusion, emotional lability, anhedonia, psychotic thoughts, mood disturbances, hypersexuality, aggressive behavior, panic attacks

Respiratory

Very common (10% or more): Oropharyngeal pain (28%), nasopharyngitis (24%), upper respiratory tract infection (21%), cough (16%), sinusitis (14%)

Common (1% to 10%): Rhinorrhea, bronchitis

Rare (0.01% to 0.1%): Dyspnea

Frequency not reported: Pulmonary arterial hypertension

Renal

Rare (Less than 0.1%): Nephrotic syndrome, glomerulosclerosis

Editorial References and Review

Medically reviewed by BestRx Medical Team Last updated on 1/1/2020.

Source: Drugs.com Avonex