Interferon alfa-2b is used to treat hairy cell leukemia, malignant melanoma, follicular lymphoma, Kaposi's sarcoma caused by AIDS, and certain types of genital warts. Interferon alfa-2b 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.

Interferon alfa-2b may also be used for purposes not listed in this medication guide.

You should not use interferon alfa-2b 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.

Interferon alfa-2b can harm an unborn baby or cause a miscarriage. Interferon alfa-2b 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 this medicine.

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.

Use Interferon Alfa-2B (Intron A) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

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.

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.

Interferon alfa-2b 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 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.

Using this medicine 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.