Peginterferon Alfa-2a (Injection)


Peginterferon Alfa-2a (peg-in-ter-FEER-on AL-fa-2a)

Treats hepatitis B and hepatitis C. May be used alone or in combination with other medicines, such as ribavirin (Copegus®, Rebetol®) or telaprevir (Incivek®).

Brand Name(s)

Pegasys, Pegasys Proclick

When This Medicine Should Not Be Used

How to Use This Medicine


  • Your doctor will prescribe your exact dose and tell you how often it should be given. This medicine is given as a shot under your skin. This medicine is usually given in the stomach (abdomen) or thigh.
  • A nurse or other health provider will give you this medicine.
  • You may be taught how to give your medicine at home. Make sure you understand all instructions before giving yourself an injection. Do not use more medicine or use it more often than your doctor tells you to.
  • This medicine should come with a Medication Guide. Ask your pharmacist for a copy if you do not have one.
  • Use this medicine on the same day each week and at about the same time of the day.
  • Double-check that you are giving yourself the correct amount of medicine if you switch between using vials and prefilled syringes or disposable autoinjectors.
  • Use the vial, syringe, or autoinjector only 1 time. You might not use all of the medicine in each vial, prefilled syringe, or autoinjector. Do not save any medicine after the container has been opened.
  • Do not shake the medicine container. Do not use medicine that has changed color or has particles in it.
  • The medicine should be at room temperature before you inject it.
  • You will be shown the body areas where this shot can be given. Use a different body area each time you give yourself a shot. Keep track of where you give each shot to make sure you rotate body areas.
  • Use a new needle and syringe each time you inject your medicine.
  • Drink extra fluids while you are using this medicine to stay hydrated, especially during the first part of your treatment.

If a dose is missed:

  • Within 1 or 2 days late: Use your medicine as soon as you can, then go back to your regular schedule next week.
  • More than 2 days late: Call your doctor for instructions.
  • Do not use extra medicine to make up for a missed dose.

How to Store and Dispose of This Medicine

  • If you store this medicine at home, keep it in the refrigerator. Do not freeze. Do not leave this medicine out of the refrigerator for more than 24 hours. Protect it from light.
  • Throw away used needles in a hard, closed container that the needles cannot poke through. Keep this container away from children and pets.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any leftover medicine, containers, and other supplies. Throw away old medicine after the expiration date has passed.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Make sure your doctor knows if you use medicine to treat HIV or AIDS such as abacavir, lamivudine, stavudine, zidovudine, Combivir®, Epivir®, Trizivir®, Zerit®, or Ziagen®. Tell your doctor if you also use telbivudine (Tyzeka®), azathioprine (Imuran®), methadone (Dolophine®), or theophylline (Slo-Bid®, Theo-Dur®).
  • Do not drink alcohol while you are using this medicine.

Warnings While Using This Medicine

  • This medicine is often used with ribavirin, and ribavirin will harm an unborn baby if the mother uses is while she is pregnant. Ribavirin will also harm a baby if the father is using it during or before the pregnancy.
  • Make sure your doctor knows if you are breastfeeding, or if you have kidney disease, other liver disease, bleeding problems, or bone marrow problems (such as low blood counts). Make sure your doctor knows if you have heart or blood vessel disease, high blood pressure, or a history of a heart attack, stroke, or heart rhythm problems.
  • Many other health problems could be made worse during treatment with this medicine. Make sure your doctor has a complete health history for you. This includes diabetes, thyroid problems, an autoimmune disorder (such as psoriasis, lupus, or arthritis), or a history of cancer.
  • You might have mood or behavior changes with this medicine, such as feeling sad, hopeless, anxious, or easily upset. You could feel nervous or hostile. Some people become violent and want to hurt themselves or others. You may see or hear unusual things. Call your doctor right away if you have any strange feelings, thoughts, or behaviors. Make sure your doctor knows if you have a history of depression, bipolar disorder, other psychiatric problems, or drug addiction.
  • You could still give hepatitis B or hepatitis C to other people while you are taking this medicine.
  • This medicine may make you bleed, bruise, or get infections more easily. Take precautions to prevent illness and injury. Avoid people who are ill, and wash your hands often. Brush and floss your teeth gently, do not play rough sports, and be careful with sharp objects.
  • This medicine, when used together with ribavirin, may affect your child's growth. Your doctor may need to check your child's height and weight during and after treatment with these medicines.
  • This medicine may make you dizzy or drowsy. Do not drive, use machines, or do anything else that could be dangerous until you know how this medicine affects you.
  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Blistering, peeling, or red skin rash
  • Bloody or severe diarrhea, stomach pain
  • Change in how much or how often you urinate, burning or painful urination
  • Chest pain, fast or uneven heartbeat
  • Fever, chills, cough, sore throat, and body aches
  • Increased thirst or appetite
  • Joint pain or stiffness
  • Sudden and severe stomach pain, nausea, vomiting, fever, lightheadedness
  • Trouble breathing
  • Unusual bleeding, bruising, or weakness
  • Unusual thoughts or behaviors, depression, irritability, nervousness, or thoughts of hurting yourself or others
  • Vision changes, blurred vision, trouble reading, or eye pain
  • Yellow skin or eyes

If you notice these less serious side effects, talk with your doctor:

  • Back, joint, or muscle pain
  • Dry mouth
  • Hair loss
  • Headache, trouble sleeping
  • Loss of appetite
  • Mild diarrhea, nausea or vomiting, upset stomach
  • Mild flu-like symptoms, such as muscle aches, low fever, or tiredness
  • Redness, pain, itching, or bruising where the shot was given

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Version Info

  • Last reviewed on 8/4/2014

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