Interferon Alfa-2b (Injection)


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

Treats hepatitis, cancer, and genital warts.

Brand Name(s)

Intron A

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, 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.
  • This medicine comes in a glass vial or prefilled syringe. You might not use all of the medicine in each vial or syringe. Use each vial or syringe one time. Do not save an open vial or syringe. If the medicine has changed color or has particles in it, do not use it.
  • The solution should be allowed to warm to 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 so you will urinate more often and help prevent kidney problems.
  • 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 the following:
    • telbivudine
    • theophylline
    • 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.
  • A negative pregnancy test is required for women who are of childbearing age before starting combination therapy with ribavirin. Female patients and female partners of male patients must use 2 forms of birth control during therapy and for 6 months after therapy ends. Female patients must have regular pregnancy tests during combination therapy.
  • Tell your doctor if you are breastfeeding, or if you have kidney disease, liver disease, heart or blood vessel disease, heart rhythm problems, high triglyceride levels, low blood pressure, bleeding problems, blood clots, colitis, diabetes, eye or vision problems, lung disease (such as COPD), thyroid problems, a weakened immune system, lupus, psoriasis, rheumatoid arthritis, or sarcoidosis. Tell your doctor if you have ever had a stroke or heart attack, or if you have ever had depression, mental illness, or addiction to drugs or alcohol.
  • This medicine may cause the following problems:
    • Depression, suicidal thoughts, or aggressive behavior
    • 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
    • Serious allergic reactions (that can be life-threatening)
    • Teeth and gum problems (when used with ribavirin)
    • Slowed growth in children
  • 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. 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.
  • 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, nausea, vomiting, loss of appetite, stomach pain, yellow skin or eyes
  • Depressed mood or 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, or fainting
  • Muscle pain, weakness, or cramps
  • Numbness, tingling, or burning pain in your hands, arms, legs, or feet
  • Sudden and severe stomach pain, nausea, vomiting, and 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, constipation, changes in appetite, weight changes
  • Hair loss
  • Headache
  • Mild skin rash, redness, itching, or bruising where the shot was given
  • Tiredness, joint or muscle pain
  • Trouble sleeping or anxiety

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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