Pegasys (Peginterferon Alfa-2a)

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  • Product Details


    Pegasys (Peginterferon Alfa-2a) is a formulation of recombinant alfa-2a interferon with a polyethylene glycol (PEG) molecule attached, which is known as pegylation. This process allows the medication to stay in the bloodstream longer, allowing for less frequent dosing. It's part of a group of drugs called interferons, which are types of proteins that the body naturally produces. Pegasys stimulates the body's immune system to fight off the viruses causing chronic hepatitis B and C.


    Pegasys is administered through a subcutaneous injection, or an injection under the skin. Patients or caregivers receive training on how to properly deliver the injection, which is generally once weekly. The exact dosage varies based on individual medical conditions, age, other medical conditions, and response to treatment. The typical dosage for chronic hepatitis B, for example, is 180 micrograms once weekly. Follow a healthcare provider’s instructions on the dosage and schedule.


    The main active ingredient in Pegasys is Peginterferon Alfa-2a.


    Individuals should avoid taking or using this medication if any of the following apply:

    • Known hypersensitivity to Peginterferon Alfa-2a or any ingredients in the formulation
    • Autoimmune hepatitis or hepatic decompensation (Child-Pugh score >6) in cirrhotic patients
    • Neonates and infants, due to the risk of developing serious infections from benzyl alcohol preservative


    • Speak with a healthcare provider about the following before starting Pegasys:
      • Other medications you take
      • If you have other medical conditions
      • Whether you have allergies
      • Whether you’re pregnant or breastfeeding
    • If you're taking Pegasys, especially with Ribavirin, there's a risk of birth defects or loss of the pregnancy. You'll need to take a pregnancy test before starting treatment, use two reliable forms of birth control, and have monthly pregnancy tests to ensure safety.
    • Some people on Pegasys might feel really down or act differently than usual. If you or those around you notice big changes in your mood or behavior, it is important to tell your doctor.
    • If you have heart problems, Pegasys could make them worse. Keep a close eye on any heart-related symptoms and talk to your doctor if anything feels off.
    • Pegasys can affect your blood cells, making you more likely to get infections or bruises easily. Your doctor will check your blood regularly to catch any issues early.
    • Sometimes, Pegasys can negatively affect the body's immune system, affecting the thyroid (which could change how your body uses energy) or leading to high blood sugar. Let your doctor know if you notice unusual symptoms.
    • Changes in vision or eye health can happen. If you notice anything different about your eyes or sight, it's crucial to get it checked out.
    • Though rare, Pegasys can increase the risk of having a stroke. Be aware of stroke signs like sudden weakness or trouble speaking, and get immediate help if they occur.
    • For those already dealing with liver issues, Pegasys can sometimes make things worse. Regular liver checks are a must.
    • Some people might have trouble breathing while on Pegasys. If breathing becomes difficult, see your doctor right away.
    • Pegasys can make it easier to catch infections. Stay vigilant for signs of infection like fever or feeling unusually tired and report them to your healthcare provider.
    • Issues like inflammation of the pancreas or colon can occur, causing severe stomach pain. If you experience this, it's important to seek medical attention.
    • Serious skin reactions, even rare ones like Stevens-Johnson syndrome, can happen. If your skin starts to change in any way, contact your doctor immediately.
    • When given with other treatments, Pegasys might affect a child's growth. Pediatric patients will be closely monitored.
    • If Pegasys is used with the drug telbivudine, it could cause nerve pain. Report any new or worsening numbness or tingling to your doctor.

    Side Effects

    Pegasys side effects may include flu-like symptoms, including tiredness, weakness, fever, chills, muscle aches, joint pain, and headaches. These symptoms can be minimized by taking Pegasys in the evening and using over-the-counter medicines recommended by a healthcare provider. Stomach pain and changes in liver blood tests are also common.

    Pegasys may cause serious issues, including blood, thyroid, and blood sugar problems, which can lead to conditions like anemia, thyroid disorders, and diabetes. There's also a risk of severe eye and liver problems, lung complications, and serious allergic reactions. Additionally, it can affect growth in children and cause nerve issues. Regular health monitoring and immediate reporting of any severe symptoms to a healthcare provider are recommended.


    1. Pegasys (Peginterferon Alfa-2a) Product Monograph. Vienna, AUT: zr pharma& GmbH; 2021.
    2. Pegasys (Peginterferon Alfa-2a) Drug Label Information. Vienna, AUT: zr pharma& GmbH; 2024.

    IMPORTANT NOTE: The above information is intended to increase awareness of health information and does not suggest treatment or diagnosis. This information is not a substitute for individual medical attention and should not be construed to indicate that use of the drug is safe, appropriate, or effective for you. See your health care professional for medical advice and treatment.

    Product Code : 14689

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