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Intron A

Generic name: interferon alfa-2bIN-ter-FEAR-on-AL-fa-2b ]
Drug class: Antineoplastic interferons

Medically reviewed by on Jun 30, 2022. Written by Cerner Multum.

What is Intron A?

Intron A is used to treat hairy cell leukemia, malignant melanoma, follicular lymphoma, Kaposi's sarcoma caused by AIDS, and certain types of genital warts. This medicine is also used to treat chronic hepatitis B or C in adults, and to treat chronic hepatitis B in children who are at least 1 year old.

Intron A may also be used for purposes not listed in this medication guide.


You should not use Intron A if you have autoimmune hepatitis, or severe liver problems from causes other than hepatitis B or C.

You should not use Intron A with ribavirin if you are pregnant, or if you are a man whose sex partner is pregnant. Use effective birth control to prevent pregnancy while taking ribavirin and for at least 6 months after your last dose.

Intron A can cause life-threatening infections, autoimmune disorders, serious mood or behavior problems, or a stroke.

Call your doctor at once if you have: unusual changes in mood or behavior, chest pain, trouble breathing, sudden numbness or weakness, or signs of infection (fever, chills, cough with mucus, or burning when you urinate).

Before taking this medicine

You should not use Intron A if you are allergic to it, or if you have:

  • autoimmune hepatitis, or severe liver problems from causes other than hepatitis B or C.

You should not use the combination of interferon alfa-2b and ribavirin if you have:

  • severe kidney disease;

  • a blood cell disorder such as thalassemia or sickle cell anemia;

  • an allergy to interferons or ribavirin;

  • if you are pregnant; or

  • if you are a man and your sex partner is pregnant.

Tell your doctor if you have ever had

  • cirrhosis or liver problems other than hepatitis;

  • depression, mental illness, thoughts about hurting yourself or someone else;

  • drug or alcohol addiction;

  • heart disease, high blood pressure, heart attack or stroke;

  • a blood clot in your lung;

  • a bleeding or blood clotting disorder;

  • eye problems;

  • asthma, COPD, or other breathing disorder;

  • diabetes, or a thyroid disorder;

  • a weak immune system, low blood cell counts;

  • colitis or other intestinal disorder;

  • kidney disease; or

  • an organ transplant.

Intron A can harm an unborn baby or cause a miscarriage. This medicine is sometimes used in combination with ribavirin. Both men and women using ribavirin should use effective birth control to prevent pregnancy. Ribavirin can cause birth defects, miscarriage, or death to an unborn baby if the mother or father is using Intron A.

You should not take ribavirin if you are pregnant, or if you are a man and your sex partner is pregnant. Use effective birth control to prevent pregnancy. Keep using birth control for at least 6 months after your last dose of ribavirin.

Tell your doctor right away if a pregnancy occurs while either the mother or the father is using ribavirin.

You should not breastfeed while using this medicine.

The powder form of interferon alfa-2b is made from human plasma (part of the blood) which may contain viruses and other infectious agents. Donated plasma is tested and treated to reduce the risk of it containing infectious agents, but there is still a small possibility it could transmit disease. Talk with your doctor about the risks and benefits of using this medication.

How is Intron A given?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Intron A is injected into a muscle, under the skin, as an infusion into a vein, or directly into a genital wart. A healthcare provider will give your first dose and may teach you how to properly use the medication by yourself.

Your dose needs may change if you switch to a different brand, strength, or form of this medicine. Avoid medication errors by using only the form and strength your doctor prescribes.

Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you don't understand all instructions.

Intron A powder must be mixed with a liquid (diluent) before using it. When using injections by yourself, be sure you understand how to properly mix and store the medicine.

Prepare your injection only when you are ready to give it. Do not use if the medicine looks cloudy, has changed colors, or has particles in it. Call your pharmacist for new medicine.

Intron A can increase your risk of bleeding or infection. You will need frequent medical tests. Your heart, lung, and liver function may also need to be checked.

Intron A can increase your risk of bleeding or infection. You will need frequent medical tests.

Store this medicine in the refrigerator. Do not freeze. After mixing the powder with a diluent, store this mixture in the refrigerator and use it within 24 hours.

Each mixture or single-use vial (bottle) of this medicine is for one use only. Throw it away after one use, even if there is still medicine left inside. Throw away any leftover medicine in a multi-dose vial 30 days after the first use.

Use a needle and syringe only once and then place them in a puncture-proof "sharps" container. Follow state or local laws about how to dispose of this container. Keep it out of the reach of children and pets.

What happens if I miss a dose?

Use the medicine as soon as you remember, and then go back to your regular injection schedule. Do not use two doses at one time.

If several days pass after you miss a dose, call your doctor for instructions.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while using Intron A?

Using Intron A will not prevent your disease from spreading. Follow your doctor's instructions about how to prevent passing the disease to another person.

Avoid drinking alcohol. It may increase your risk of liver damage.

Avoid driving or hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.

Intron A side effects

Get emergency medical help if you have signs of an allergic reaction: hives, skin rash with blistering and peeling; anxiety, chest pain, difficult breathing; swelling of your face, lips, tongue, or throat.

Intron A may cause serious side effects. Call your doctor at once if you have:

  • new or worsening cough, fever, trouble breathing;

  • depression, irritability, confusion, thoughts about hurting yourself or others, or falling back into a previous pattern of drug addiction;

  • vision changes;

  • problems with your teeth;

  • severe stomach pain with bloody diarrhea;

  • sudden numbness or weakness (especially on one side of the body), slurred speech, problems with balance;

  • heart problems--chest pain or pressure, fast heartbeats, sweating, feeling light-headed;

  • new or worsened autoimmune disorders--skin problems, joint pain or swelling, cold feeling or pale appearance in your fingers or toes;

  • signs of infection--fever, chills, body aches, cough with yellow or pink mucus, pain or burning when you urinate; or

  • signs of liver or pancreas problems--loss of appetite, upper stomach pain (that may spread to your back), nausea or vomiting, dark urine, jaundice (yellowing of the skin or eyes).

Your cancer treatments may be delayed or permanently discontinued if you have certain side effects.

Intron A with ribavirin can affect growth in children. Talk with your doctor if you think your child is not growing at a normal rate while using this medicine.

Common side effects of Intron A may include:

  • flu-like symptoms, headache, feeling tired;

  • nausea, diarrhea, loss of appetite;

  • thinning hair; or

  • swelling, pain, or burning where an injection was given.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Intron A?

Tell your doctor about all your other medicines, especially:

This list is not complete. Other drugs may affect Intron A, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Further information

  • Your doctor or can provide more information about Intron A.

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.