Peginterferon Alfa-2a
Peginterferon Alfa-2a is a pegylated form of interferon alfa-2a used to treat chronic hepatitis B and C infections. It works by enhancing the body's antiviral immune response through modulation of the innate immune system. This medication is typically prescribed when antiviral therapy is indicated for these chronic viral infections.
Peginterferon Alfa-2a is an immunomodulatory antiviral agent used to treat chronic hepatitis B and C infections.
This medication carries a boxed (black box) warning — the strongest type of FDA warning. Review the full prescribing information before use.
Key facts at a glance
- ATC
- L03AB11
- RxNorm
- 120608
- Generic
- Peginterferon Alfa-2a
- Class
- atc-l03
- Brands
- Pegasys
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- prefilled syringe, injection, solution
- 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
- 180 mcg once weekly
- Maximum
- consult physician
- Frequency
- once weekly
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 180 mcg/m² once weekly
- Maximum
- consult physician
- Frequency
- once weekly
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 180 mcg once weekly
- Maximum
- consult physician
- Frequency
- once weekly
- 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 if pregnancy occurs
regular fetal monitoring and ultrasound assessments
Use of this medication in this population requires careful consideration of risks and benefits.
pregnancy
second trimesteravoid if possible
avoid use during pregnancy unless benefits outweigh risks
regular fetal monitoring
Use of this medication in this population requires careful consideration of risks and benefits.
pregnancy
third trimesteravoid if possible
avoid use during pregnancy; consider alternative antiviral therapy
regular fetal monitoring and growth assessments
Use of this medication in this population requires careful consideration of risks and benefits.
lactation
breastfeedinguse with caution
breastfeeding not recommended during treatment due to potential transfer to infant; decide whether to discontinue nursing or discontinue drug
monitor infant for signs of infection or adverse effects
Use with caution and monitor for adverse effects.
pediatric_age
children 5 years and olderweight-based dosing required
approved for pediatric patients with hepatitis B and C; dosing based on body surface area; monitor growth and development closely
regular monitoring of growth parameters, blood counts, and liver function
Use with caution and monitor for adverse effects.
geriatric
elderly 65 years and olderstart at lower end of dosing range
use with caution; increased susceptibility to adverse effects including flu-like symptoms and depression; consider dose reduction
close monitoring of hematologic parameters, thyroid function, and for signs of depression
Use with caution and monitor for adverse effects.
renal_impairment
severe renal impairmentreduce dose for severe impairment; no adjustment needed for mild-moderate
for patients with creatinine clearance below 30 mL/min, use reduced dose; monitor renal function closely
regular monitoring of renal function and blood counts
Use with caution and monitor for adverse effects.
hepatic_impairment
decompensated cirrhosiscontraindicated
do not use in patients with decompensated liver disease including ascites, variceal bleeding, or hepatic encephalopathy
monitor liver function tests and for signs of hepatic decompensation
Use of this medication in this population requires careful consideration of risks and benefits.
hepatic_impairment
compensated cirrhosisno specific dose adjustment
use with caution in patients with compensated cirrhosis; monitor closely for signs of hepatic decompensation
regular monitoring of liver function, bilirubin, and for signs of portal hypertension
Use with caution and monitor for adverse effects.
Statistics and clinical data
FDA approval year
Initial FDA approval for hepatitis C treatment
Drug class
ATC classification as pegylated interferon
Mechanism of action
Pharmacodynamic mechanism description
Primary indications
FDA-approved therapeutic indications
Treatment of chronic hepatitis B and hepatitis C infections in adults. May be used as monotherapy or in combination with other antiviral agents depending on the specific condition and treatment regimen.
Peginterferon Alfa-2a binds to interferon receptors on cell surfaces, activating intracellular signaling pathways that induce expression of antiviral proteins. This enhances the innate immune response against viral infections and helps control viral replication.
Administered by subcutaneous injection. Requires monitoring for potential side effects including flu-like symptoms, neuropsychiatric effects, and hematologic abnormalities. Contraindicated in patients with certain autoimmune disorders, severe hepatic impairment, or hypersensitivity to interferon alfa-2a. Pregnancy should be avoided during treatment due to potential fetal harm.
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