Interferon Beta-1a
Interferon Beta-1a (Rebif) is a biologic medication used to treat relapsing forms of multiple sclerosis. It is a recombinant version of a naturally occurring protein that helps regulate the immune system. The exact mechanism by which it reduces MS flare-ups and slows disease progression is not fully understood.
Interferon Beta-1a is an injectable immunomodulator used to reduce MS relapses and slow disease progression.
Key facts at a glance
- ATC
- L03AB07
- RxNorm
- 75917
- Generic
- Interferon Beta-1a
- Class
- atc-l03
- Brands
- Avonex, Rebif
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- prefilled syringe, injection
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 500mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 250mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 400mg daily
- Maximum
- consult physician
- Frequency
- once daily
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
9 groupspregnancy
first trimesteravoid if possible
avoid use during pregnancy unless benefits outweigh risks; discontinue therapy if pregnancy occurs
regular fetal monitoring
Use of this medication in this population requires careful consideration of risks and benefits.
pregnancy
second third trimesteravoid
continue to avoid use throughout pregnancy; consider switching to safer alternatives
regular prenatal care and fetal monitoring
Use of this medication in this population requires careful consideration of risks and benefits.
lactation
breastfeedingno specific adjustment
decide whether to discontinue nursing or discontinue therapy; monitor infant for adverse effects
monitor nursing infant for symptoms such as fever, lethargy, or feeding problems
Use with caution and monitor for adverse effects.
pediatric_age
under 18 yearsnot established
safety and effectiveness not established in pediatric patients; use only in clinical trials or as per specialist recommendation
careful monitoring of growth and development
geriatric
over 65 yearsno specific adjustment needed
use with caution; consider comorbidities and organ function
monitor renal and hepatic function regularly; watch for cardiovascular adverse effects
Use with caution and monitor for adverse effects.
renal_impairment
mild to moderateno specific dose adjustment required
use with caution; monitor renal function regularly
monitor serum creatinine and renal function tests periodically
Use with caution and monitor for adverse effects.
renal_impairment
severeconsider dose reduction
use with caution; consider dose reduction and close monitoring
frequent monitoring of renal function and drug levels if available
Use with caution and monitor for adverse effects.
hepatic_impairment
mild to moderateno specific adjustment
use with caution; monitor liver enzymes
regular monitoring of liver function tests including ALT, AST
Use with caution and monitor for adverse effects.
hepatic_impairment
severeavoid use
avoid use in patients with severe hepatic impairment; consider alternative therapies
frequent liver function monitoring if use is unavoidable
Use of this medication in this population requires careful consideration of risks and benefits.
Statistics and clinical data
FDA approval year
Avonex was the first interferon beta-1a approved for MS treatment
Drug class
Immunomodulator belonging to the interferon family of biologic medications
Primary indication
Main therapeutic use for MS management
Route of administration
Avonex is administered IM weekly; Rebif is administered subcutaneously three times weekly
Rebif is FDA-approved for the treatment of relapsing forms of multiple sclerosis, including clinically isolated syndrome, relapsing-remitting MS, and active secondary progressive MS in adults.
The exact mechanism is unknown. It is believed to work by binding to interferon receptors on immune cells, which may reduce inflammation and modulate immune responses that attack the nervous system. This may help decrease the frequency of relapses and reduce the formation of new brain lesions.
Rebif is administered by subcutaneous injection, typically three times per week. Common side effects include flu-like symptoms (fever, chills, muscle aches), injection site reactions, and liver enzyme elevations. Depression, thyroid problems, and severe allergic reactions may occur. Regular blood tests are required to monitor for liver and blood cell abnormalities. It should not be used during pregnancy.
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 26, 2026. · Read our editorial policy