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Peginterferon Alfa-2a

Adult Medication

Brand Names: US

Pegasys; Pegasys ProClick

Brand Names: Canada



  • Alpha interferons may cause or make diseases of the mind worse. Taking one’s own life, ideas of killing yourself or murder, low mood (depression), forceful actions, hallucinations, psychoses, and relapse of drug addiction have happened during treatment and within 6 months after the last dose. Alpha interferons may also cause or make infections, blood flow problems, or autoimmune diseases worse. Some of these may be deadly. If you think you have any of these health problems, call your doctor right away. Side effects such as high or low blood pressure, a fast heartbeat, a heartbeat that does not feel normal, chest pain or pressure, trouble breathing, and heart attacks have happened while taking alpha interferons. If you have very bad signs or if signs of these health problems get worse, talk with your doctor about stopping this drug. Problems are most often fixed after you stop the drug.

What is this drug used for?

  • It is used to treat hepatitis B and C infections.

What do I need to tell my doctor BEFORE I take this drug?

  • If you have an allergy to this drug or any part of this drug.
  • If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
  • If you have ever had any of these health problems: Autoimmune hepatitis or liver disease.
  • If you have had a transplant.
  • If you are breast-feeding or plan to breast-feed.
This is not a list of all drugs or health problems that interact with this drug.
Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this drug with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take this drug?

  • Tell all of your health care providers that you take this drug. This includes your doctors, nurses, pharmacists, and dentists.
  • Avoid driving and doing other tasks or actions that call for you to be alert until you see how this drug affects you.
  • Tell your doctor if you have signs of high or low blood sugar like breath that smells like fruit, dizziness, fast breathing, fast heartbeat, feeling confused, feeling sleepy, feeling weak, flushing, headache, more thirsty or hungry, passing urine more often, shaking, or sweating.
  • Check your blood sugar as you have been told by your doctor.
  • Low blood cell counts have happened with this drug. If blood cell counts get very low, this can lead to bleeding problems, infections, or anemia. Call your doctor right away if you have signs of infection like fever, chills, or sore throat; any unexplained bruising or bleeding; or if you feel very tired or weak.
  • Avoid drinking alcohol while taking this drug.
  • Very bad and sometimes deadly pancreas problems (pancreatitis) have happened with this drug. Call your doctor right away if you have very bad stomach pain, very bad back pain, or very upset stomach or throwing up.
  • A very bad skin reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis) may happen. It can cause very bad health problems that may not go away, and sometimes death. Get medical help right away if you have signs like red, swollen, blistered, or peeling skin (with or without fever); red or irritated eyes; or sores in your mouth, throat, nose, or eyes.
  • Very bad and sometimes deadly lung problems have happened with this drug. Call your doctor right away if you have lung or breathing problems like trouble breathing, shortness of breath, or a cough that is new or worse.
  • It is not known if this drug will prevent liver failure or other liver problems like cancer. Talk with the doctor.
  • This drug does not stop the spread of diseases like HIV or hepatitis that are passed through blood or having sex. Do not have any kind of sex without using a latex or polyurethane condom. Do not share needles or other things like toothbrushes or razors. Talk with your doctor.
  • This drug may affect growth in children and teens in some cases. They may need regular growth checks. Talk with the doctor.
  • Some products have benzyl alcohol. Do not give a product that has benzyl alcohol in it to a newborn or infant. Talk with the doctor to see if this product has benzyl alcohol in it.
  • This drug caused fertility problems in animals. It is not known if it will cause fertility problems in humans. Talk with the doctor.
  • This drug may cause harm to the unborn baby if you take it while you are pregnant.
  • If you are able to get pregnant, a pregnancy test will be done to show that you are NOT pregnant before starting this drug. Talk with your doctor.
  • Use birth control that you can trust to prevent pregnancy while taking this drug.
  • If you are pregnant or you get pregnant while taking this drug, call your doctor right away.

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:
  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of high blood pressure like very bad headache or dizziness, passing out, or change in eyesight.
  • Signs of thyroid problems like a change in weight without trying, feeling nervous and excitable, feeling restless, feeling very weak, hair thinning, low mood (depression), neck swelling, not able to focus, not able to handle heat or cold, period (menstrual) changes, shakiness, or sweating.
  • Shortness of breath, a big weight gain, or swelling in the arms or legs.
  • Weakness on 1 side of the body, trouble speaking or thinking, change in balance, drooping on one side of the face, or blurred eyesight.
  • Memory problems or loss.
  • Not able to focus.
  • Feeling irritable.
  • This drug may cause eye problems that may lead to loss of eyesight or blindness. Tell your doctor if you have or have ever had eye problems. Call your doctor right away if you have any changes in eyesight.
  • Very bad and sometimes deadly liver problems have happened with this drug. Call your doctor right away if you have signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
  • Very bad and sometimes deadly bowel problems (colitis) have happened within 12 weeks of treatment with alpha interferons like this drug. Call your doctor right away if you have very bad belly pain, bloody loose stools, throwing up blood, or throw up that looks like coffee grounds.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:
  • Flu-like signs.
  • Upset stomach or throwing up.
  • Loose stools (diarrhea).
  • Not hungry.
  • Belly pain.
  • Dry mouth.
  • Muscle or joint pain.
  • Back pain.
  • Headache.
  • Dizziness.
  • Hair loss.
  • Not able to sleep.
  • Feeling tired or weak.
  • Sweating a lot.
  • Irritation where the shot is given.
These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.
You may report side effects to your national health agency.

How is this drug best taken?

Use this drug as ordered by your doctor. Read all information given to you. Follow all instructions closely.
  • It is given as a shot into the fatty part of the skin on the top of the thigh or the belly area.
  • The shot is most often given once a week.
  • If you will be giving yourself the shot, your doctor or nurse will teach you how to give the shot.
  • Follow how to use as you have been told by the doctor or read the package insert.
  • Wash your hands before and after use.
  • Before giving the shot, let it come to room temperature. Do not heat this drug.
  • Do not shake.
  • Do not use if the solution is cloudy, leaking, or has particles.
  • Do not use if solution changes color.
  • Move the site where you give the shot with each shot.
  • Throw syringe away after use. Do not use the same syringe more than one time.
  • Throw away needles in a needle/sharp disposal box. Do not reuse needles or other items. When the box is full, follow all local rules for getting rid of it. Talk with a doctor or pharmacist if you have any questions.
  • Drink lots of noncaffeine liquids unless told to drink less liquid by your doctor.
  • Have blood work checked as you have been told by the doctor. Talk with the doctor.
  • Have an eye exam as you have been told by your doctor.
  • If you are taking theophylline, talk with your doctor. You may need to have your blood work checked more closely while you are taking it with this drug.
  • This drug may be used with other drugs to treat your health condition. If you are also taking other drugs, talk with your doctor about the risks and side effects that may happen.
  • Do not switch between this product and other products that have the same drugs in them without checking with the doctor.

What do I do if I miss a dose?

  • Take a missed dose as soon as you think about it and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.
  • If you miss your dose by more than 2 days, call your doctor to find out what to do.

How do I store and/or throw out this drug?

  • Store in a refrigerator. Do not freeze.
  • Throw away unopened drug if left at room temperature for more than 24 hours.
  • Protect from light.
  • Throw away any part left over after the dose is given.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.

General drug facts

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else’s drugs.
  • Keep a list of all your drugs (prescription, natural products, vitamins, OTC) with you. Give this list to your doctor.
  • Talk with the doctor before starting any new drug, including prescription or OTC, natural products, or vitamins.
  • Some drugs may have another patient information leaflet. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Consumer Information Use and Disclaimer

This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.

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© 2018 Wolters Kluwer Clinical Drug Information, Inc. and its affiliates and/or licensors. All rights reserved.

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