Health Guide

Interferon Alfa-2b (By injection)

Interferon Alfa-2b (in-ter-FEER-on AL-fa-2b)

Treats hepatitis, cancer, and genital warts.

Brand Name(s):

Intron A

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. You should not receive it if you had an allergic reaction to interferon alfa-2b, or if you have autoimmune hepatitis.

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, into a muscle, or into a vein.
  • 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.
  • Do not save an open vial or syringe. Do not use the medicine if it has changed color or has particles in it.
  • Allow the solution to warm to room temperature before you inject it.
  • This medicine should come with a Medication Guide. Ask your pharmacist for a copy if you do not have one.
  • Missed dose: You must use this medicine on a fixed schedule. Call your doctor or pharmacist if you miss a dose.
  • If you store this medicine at home, keep it in the refrigerator. Do not freeze.
  • Throw away used needles in a hard, closed container that the needles cannot poke through. Keep this container away from children and pets.

Drugs and Foods to Avoid:

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

  • Some medicines can affect how interferon alfa-2b works. Tell your doctor if you are using telbivudine, theophylline, or zidovudine.

Warnings While Using This Medicine:

  • This medicine may cause birth defects if either partner is using it together with ribavirin during conception or pregnancy. Tell your doctor right away if you or your partner becomes pregnant. Female patients and female partners of male patients must use 2 forms of birth control during treatment and for 6 months after treatment ends. Female patients must have regular pregnancy tests during combination treatment.
  • Tell your doctor if you are breastfeeding, or if you have kidney disease, liver disease (including cirrhosis), bleeding problems, colitis, diabetes, eye or vision problems, heart or blood vessel disease, heart rhythm problems, high triglyceride levels, lung disease (such as COPD), thyroid problems, or an autoimmune disorder (such as lupus, psoriasis, rheumatoid arthritis, or sarcoidosis). Tell your doctor if you have a history of stroke, blood clots, heart attack, depression, mental health problems, or addiction to drugs or alcohol.
  • This medicine may cause the following problems:
    • Depression, unusual moods or behaviors, thoughts of hurting yourself or others
    • Heart problems
    • New or worsening diabetes, thyroid problems, or autoimmune disorders
    • New or worsening lung or liver problems
    • Inflammation of the pancreas or intestines
    • Vision changes or eye problems
  • The powder form of this medicine contains albumin, which comes from human blood. All donated blood is tested for certain viruses. Although your risk for getting a virus from the medicine is very low, talk with your doctor if you have concerns.
  • This medicine may make you tired or unable to concentrate. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.
  • This medicine may make you bleed, bruise, or get infections more easily. Take precautions to prevent illness and injury. Wash your hands often.
  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

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
  • Chest pain or trouble breathing
  • Dark urine or pale stools, loss of appetite, stomach pain, yellow skin or eyes
  • Depression, unusual moods or behaviors, thoughts of hurting yourself or others
  • Diarrhea that contains blood
  • Fast, slow, pounding, or uneven heartbeat
  • Fever, chills, cough, sore throat, stuffy or runny nose
  • Lightheadedness, dizziness, fainting
  • Numbness, tingling, or burning pain in your hands, arms, legs, or feet
  • Sudden and severe stomach pain, nausea, vomiting, fever
  • Sudden or severe headache, problems with speech or movement
  • Unusual bleeding, bruising, or weakness
  • Vision changes

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

  • Diarrhea, loss of appetite
  • Hair loss
  • Headache, joint or muscle pain
  • Mild skin rash, redness, 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

Last Updated: 7/4/2018
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