Generic Name: pegylated interferon alfa-2a

Pronunciation: N/A

Abbreviation: N/A

Other Market Name: N/A

Drug Class: Recombinant Human Interferon Alfa

Company: Genentech

Approval Status: Approved

Generic Version Available: No

Experimental Code: N/A

Drug Indication

Peginterferon was the first-generation HCV treatment, and it is rarely used as a first-line treatment in the U.S. except when combined with Sovaldi (sofosbuvir) and ribavirin to treat genotype 3.

General Info

Peginterferon is an injectable medication. Pegasys needs to be refrigerated. The cure rates of PEG depend on the treatment regimen it is prescribed with, along with genotype, prior treatment and the presence of cirrhosis.


Adult Dose: PEG is injected once weekly. Pegasys is a fixed dose.

Pediatric Dose: Pegasys is approved to use in children 5 years and older. The total daily dose is usually determined by body surface.

Dosing Info: Duration of treatment and choice of drugs prescribed with peginterferon are determined by genotype, prior-treatment experience and the presence of cirrhosis. For specific treatment recommendations, see Hepatitis C Treatment-Naive Recommendations or Hepatitis C Re-treatment Recommendations.

Side Effects

  • Many side effects are associated with peginterferon, ranging from mild to severe in intensity. Peginterferon may cause or aggravate life-threatening neuropsychiatric, autoimmune, ischemic or infectious disorders.
  • Some common side effects are cough, runny nose, sore throat, depression, irritability, moodiness, anxiety, dizziness, dry mouth/skin/eyes, fatigue, weakness flu-like symptoms (chills, fever, joint and muscle aches), gastrointestinal disorders (abdominal pain, decreased appetite, diarrhea, nausea), hair loss, headache, injection site reaction, insomnia, neutropenia (low white cells), pain (back, joint, muscle), and thrombocytopenia (low platelets).
  • Side effects many increase depending on which medications are prescribed with peginterferon.

Drug Interactions

  • For a review of drug interactions, including prescription and over-the-counter medications and supplements that should not be taken with Pegasys or may require dose adjustments, consult the Pegasys package insert.

Other Info

  • Since peginterferon is prescribed with ribavirin, a drug that may harm fetuses, it should not be taken by pregnant women or those who are trying to become pregnant. Women of childbearing age and their male sexual partners must use two forms of birth control throughout treatment and for six months after treatment if ribavirin is prescribed.
  • Since peginterferon is prescribed with ribavirin, taking while breast-feeding is not recommended.

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Last Reviewed: December 22, 2021