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Peginterferon Alfa 2a

Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

  • Black, tarry stools
  • Chills
  • Cough
  • Discouragement
  • Feeling sad or empty
  • Fever
  • Irritability
  • Lack of appetite
  • Loss of interest or pleasure
  • Lower back or side pain
  • Painful or difficult urination
  • Pale skin
  • Shortness of breath
  • Sore throat
  • Tiredness
  • Trouble with concentrating
  • Trouble with sleeping
  • Ulcers, sores, or white spots in the mouth
  • Unusual bleeding or bruising
  • Unusual tiredness or weakness

Less common

  • Bone pain
  • Chest pain or discomfort
  • Confusion
  • Constipation
  • Depressed mood
  • Dizziness
  • Dry skin and hair
  • Fainting
  • Fast heartbeat
  • Feeling cold
  • Hair loss
  • Headache
  • Heart murmur
  • Hives
  • Hoarseness or husky voice
  • Lightheadedness
  • Muscle cramps and stiffness
  • Pale skin
  • Rapid, shallow breathing
  • Slowed heartbeat
  • Sneezing
  • Stomach pain
  • Tightness in the chest
  • Troubled breathing with exertion
  • Weight gain
  • Wheezing

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Back pain
  • Blistering, crusting, irritation, itching, or reddening of the skin
  • Cracked, dry, scaly skin
  • Diarrhea
  • Dry mouth
  • Fear
  • Feeling unusually cold, shivering
  • Hair loss or thinning of the hair
  • Muscle or joint pain
  • Nervousness
  • Numbness
  • Pain
  • Rash
  • Redness
  • Scarring
  • Soreness
  • Stinging
  • Stomach pain
  • Swelling
  • Tenderness
  • Tingling
  • Ulceration
  • Vomiting
  • Warmth

Less common

  • Acid or sour stomach
  • Belching
  • Blurred vision
  • Heartburn
  • Indigestion
  • Memory problems
  • Stomach discomfort or upset

Incidence not known

  • Change of hearing
  • Loss of hearing

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

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


It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Using peginterferon alfa-2a together with ribavirin while you are pregnant can harm your unborn baby. These medicines may also cause birth defects if the father is using it when his sexual partner becomes pregnant. If a pregnancy occurs while you are using these medicines, tell your doctor right away. Your doctor may want you to join a pregnancy registry for patients taking this medicine with ribavirin.

A negative pregnancy test is needed for women who are of childbearing age before starting treatment with this medicine and ribavirin. Two forms of birth control must be used during treatment and for 6 months after treatment ends. You will need to have pregnancy tests done every month while you receive these medicines and after your treatment ends.

This medicine contains benzyl alcohol which may cause serious reactions to newborn or premature infants. Discuss this with your doctor if you are concerned.

You should not use this medicine if you are also taking didanosine (Videx®, Videx® EC) while you are using this medicine. Using these medicines together may cause serious problems.

This medicine may cause some people to be agitated, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. If you, your child, or your caregiver notice any of these side effects, tell your doctor or your child’s doctor right away.

This medicine may cause serious types of allergic reactions, including anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Stop using this medicine and call your doctor right away if you have itching, hives, hoarseness, trouble with breathing, trouble with swallowing, or any swelling of the hands, face, or mouth while you or your child are using this medicine.

Serious skin reactions can occur with this medicine. Stop using this medicine and check with your doctor right away if you have blistering, peeling, or loosening of the skin; fever or chills; hives or welts; red skin lesions; a severe skin rash or acne; or sores or ulcers on the skin while you or your child are using this medicine.

This medicine will not keep you from giving hepatitis B or hepatitis C to other people.

This medicine combined with ribavirin can temporarily lower the number of white blood cells in your blood, which will increase the chance of getting an infection. It can also lower the number of platelets, which are necessary for proper blood clotting. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:

  • If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.
  • Check with your doctor immediately if you notice any unusual bleeding or bruising; black, tarry stools; blood in the urine or stools; or pinpoint red spots on your skin.
  • Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.
  • Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else in the meantime.
  • Be careful not to cut yourself when you are using sharp objects such as a safety razor or fingernail or toenail cutters.
  • Avoid contact sports or other situations where bruising or injury could occur.

Check with your doctor right away if you or your child have back, leg, or stomach pains; bleeding gums; chills; dark urine; difficulty breathing; fever; general body swelling; headache; loss of appetite; nausea or vomiting; nosebleeds; pale skin; sore throat; unusual tiredness or weakness; or yellowing of the eyes or skin. These could be symptoms of a blood disorder called anemia.

Stop using this medicine and check with your doctor right away if you or your child have symptoms that could lead to pancreatitis. This includes sudden and severe stomach pain, chills, constipation, nausea, vomiting, fever, or lightheadedness.

Check with your doctor immediately if blurred vision, difficulty in reading, eye pain, or any other change in vision occurs during or after treatment. Your doctor may want you or your child to have your eyes checked by an ophthalmologist (eye doctor).

Peginterferon alfa-2a 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.

Peripheral neuropathy may occur if you use this medicine together with telbivudine (Tyzeka®). Check with your doctor right away if you or your child are having burning, numbness, tingling, or painful sensations in the arms, hands, legs, or feet.

This medicine may cause some people to become drowsy, dizzy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy and not alert.

Avoid drinking alcohol (including beer, wine, or liquor) while you are using this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Proper Use

A nurse or other trained health professional may give you or your child this medicine. This medicine is given as a shot under your skin (usually in the abdomen or stomach, or thighs). You may also be taught how to give this medicine at home. Make sure you understand all of the instructions before giving yourself an injection. Do not use more medicine or use it more often than your doctor tells you to.

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.

Each package of peginterferon alfa-2a contains a Medication Guide and patient instructions. Read the instructions carefully and make sure you understand:

  • How to prepare the injection.
  • Proper use of disposable syringes.
  • How to give the injection.
  • How long the injection is stable.

If you have any questions about any of this, check with your doctor.

This medicine is available in 3 dosage forms: a vial (glass container), a prefilled syringe, or a disposable autoinjector. If you switch from using the vial to using the prefilled syringe or autoinjector, double-check that you are giving yourself the correct amount of medicine.

You might not use all of the medicine in each vial (glass container), prefilled syringe, or disposable autoinjector. Use each vial, syringe, or autoinjector only one time. Do not save an open vial, syringe, or autoinjector. If the medicine in the vial or syringe has changed color, or if you see particles in it, do not use it.

Drink extra fluids while you are using this medicine. This will keep you well hydrated, especially during the first stages of your treatment.

Use only the brand of this medicine that your doctor prescribed. Different brands may not work the same way.


The dose of this medicine will be different for different patients. Follow your doctor’s orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For injection dosage form:
    • For hepatitis B and hepatitis C:
      • Adults—Dose is based on body weight and must be determined by your doctor. It is usually 180 micrograms (mcg) injected under the skin once a week for 48 weeks. The medicine should be used on the same day each week and at approximately the same time.
      • Children—Use and dose must be determined by your doctor.
    • For hepatitis C infection, in combination with ribavirin:
      • Adults—Dose is based on body weight and must be determined by your doctor. It is usually 180 micrograms (mcg) injected under the skin once weekly (same time and day each week) and should be taken together with ribavirin twice daily for 24 to 48 weeks. The length of time will be determined by your doctor.
      • Children 5 years of age and older—Dose is based on body weight or body size and must be determined by your doctor. It is usually 180 mcg injected under the skin once weekly (same time and day each week) and should be taken together with ribavirin twice daily for 24 to 48 weeks. The length of time will be determined by your doctor.
      • Children younger than 5 years of age—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

If you miss a dose or forget to use your medicine and you are 1 or 2 days late, use it as soon as you can. If it has been more than 2 days since you were supposed to use the medicine, call your doctor for instructions.


Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Store 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.

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies have not been performed on the relationship of age to the effects of peginterferon alfa-2a in children younger than 5 years of age. Safety and efficacy have not been established. Do not give this medicine to a baby younger than 1 year of age.


Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of peginterferon alfa-2a in the elderly. However, elderly patients are more likely to have age-related kidney problems, which may require caution and an adjustment in the dose for patients receiving peginterferon alfa-2a.


Pregnancy Category Explanation
All Trimesters C Animal studies have shown an adverse effect and there are no adequate studies in pregnant women OR no animal studies have been conducted and there are no adequate studies in pregnant women.


There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Theophylline

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Methadone

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Allergic reactions (e.g., anaphylaxis, bronchoconstriction, Stevens-Johnson syndrome) or
  • Autoimmune hepatitis (serious liver disease) or
  • Decompensated liver disease—Should not be used in patients with these conditions.
  • Bleeding problems, history of or
  • Bone marrow problems (e.g., aplastic anemia) or
  • Breathing problems or other lung diseases (e.g., chronic obstructive pulmonary disease or COPD, pneumonia, pulmonary infiltrates, sarcoidosis) or
  • Depression, history of or
  • Diabetes or
  • Diabetic retinopathy (eye problem caused by diabetes) or
  • Eye or vision problems (e.g., optic neuritis, retinopathy) or
  • Heart or blood vessel disease or
  • Hyperglycemia (high blood sugar) or
  • Hypoglycemia (low blood sugar) or
  • Kidney disease (e.g., interstitial nephritis) or
  • Liver disease (including cirrhosis), severe or
  • Manic episodes (bipolar depression), history of or
  • Myositis (muscle pain) or
  • Psoriasis (skin disease) or
  • Psychiatric problems, history of or
  • Rheumatoid arthritis or
  • Stroke, history of or
  • Systemic lupus erythematosus (SLE) (immune system disorder) or
  • Thyroid disease—Use with caution. May make these conditions worse.
  • Blood problems (e.g., spherocytosis) or
  • Stomach or bowel problems (e.g., bleeding), history of—Use with caution. May increase risk for severe anemia.
  • Chest pain or
  • Heart attack, history of or
  • Heart or blood vessel disease or
  • Heart rhythm problems (e.g., arrhythmia), history of or
  • Hypertension (high blood pressure)—Use with caution. Patients with these conditions should be closely monitored while using this medicine.
  • Colitis (inflammation of the bowel) or
  • Pancreatitis (inflammation of the pancreas)—Peginterferon alfa-2a should be stopped in patients with these conditions.
  • Heart disease (severe or unstable), history of or
  • Liver disease, severe or
  • Sickle-cell anemia (red blood cell disorder) or
  • Thalassemia major (genetic blood disorder)—Peginterferon alfa-2a together with ribavirin should not be used in patients with these conditions.
  • Infection (e.g., bacteria, virus, or fungus)—May decrease your body’s ability to fight infection.
  • Kidney disease—Higher blood levels of peg-interferon alfa-2a can occur, which increases the risk of serious side effects.
  • Organ transplant (e.g., liver, kidney)—Use of this medicine have not been established in patients with this condition.


Peginterferon alfa-2a is a synthetic (man-made) version of a substance that is normally produced in the body to fight infection. Peginterferon alfa-2a is used alone or together with ribavirin to treat chronic hepatitis C infection. It is used for patients who have never been treated by alpha interferons. Peginterferon alfa-2a is also used to treat adult patients with HBeAg positive and negative chronic hepatitis B. It is used in patients who have liver disease and evidence of viral replication and liver inflammation.

This medicine is available only with your doctor’s prescription.