Description and Brand Names

Drug information provided by: Merative, Micromedex®

US Brand Name

  1. Intron A


Interferon alfa-2b injection is used to treat hepatitis B and C, lymphoma (lymph node cancer), malignant melanoma (skin cancer), genital warts, hairy cell leukemia (blood cell cancer), and Kaposi sarcoma (AIDS-related tumor). Interferons are substances produced by cells in the body to help fight infections and tumors. Interferon alfa-2b is a synthetic (man-made) version of these substances.

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

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 performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of interferon alfa-2b injection in children 1 to 17 years of age with hepatitis B or children 3 to 16 years of age with hepatitis C.

Appropriate studies have not been performed on the relationship of age to the effects of interferon alfa-2b injection in children with lymphoma, malignant melanoma, genital warts, hairy cell leukemia, and Kaposi sarcoma. Safety and efficacy have not been established.


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


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 receiving 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 not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

  • Fezolinetant

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.

  • Bendamustine
  • Clozapine
  • Pirfenidone
  • Triclabendazole

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.

  • Ribavirin

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:

  • Autoimmune disorders (eg, psoriasis, Raynaud disease, rhabdomyolysis, rheumatoid arthritis, sarcoidosis, systemic lupus erythematosus, or vasculitis) or
  • Blood clotting problems (eg, pulmonary embolism, thrombophlebitis) or
  • Bone marrow problems or
  • Bowel problems (eg, colitis) or
  • Depression or mental illness, history of or
  • Diabetes or
  • Diabetic retinopathy (diabetic eye problem) or
  • Eye or vision problems (eg, retinopathy, optic neuritis) or
  • Heart attack, history of or
  • Heart or blood vessel disease, history of or
  • Heart rhythm problems (eg, arrhythmia) or
  • Hypertensive retinopathy (eye problem caused by high blood pressure) or
  • Hypertriglyceridemia (high triglycerides in the blood) or
  • Hypotension (low blood pressure) or
  • Liver disease (including cirrhosis), severe or
  • Lung disease or other breathing problems (eg, COPD), history of or
  • Stroke, history of or
  • Thyroid problems—Use with caution. May make these conditions worse.
  • Autoimmune hepatitis (liver inflammation) or
  • Human immunodeficiency virus (HIV) infection or
  • Kidney disease, severe or
  • Liver or other organ transplant or
  • Sickle cell anemia (red blood cell disorder) or
  • Thalassemia major (genetic blood disorder) or
  • Weakened immune system—Should not be used in patients with these conditions.
  • Kidney disease—Use with caution. The effects may be increased because of slower removal of the medicine from the body.

Proper Use

A nurse or other trained health professional will give you this medicine. You may also be taught how to give your medicine at home. This medicine is given as a shot under your skin, into a muscle or vein, or directly into a skin lesion.

If you are injecting interferon alfa-2b yourself, use it exactly as directed by your doctor. Do not use more or less of it, and do not use it more often than your doctor ordered. The exact amount of medicine you need has been carefully worked out. Using too much will increase the risk of side effects, while using too little may not improve your condition.

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

This medicine comes in a vial (glass container) or prefilled syringe. You might not use all of the medicine in each vial or syringe. Use them only one time and 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 in the vial or prefilled syringe should be allowed to warm to room temperature before injecting it.

Use a new needle and syringe each time you inject your medicine.

Drink extra fluids so you will pass more urine while you are using this medicine. This will keep your kidneys working well and help prevent kidney problems.

This medicine comes with a Medication Guide. Read this information carefully and make sure you understand:

  • How to prepare the injection.
  • The 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 information, talk with your doctor.

Missed Dose

This medicine needs to be given on a fixed schedule. If you miss a dose or forget to use your medicine, call your doctor or pharmacist for instructions.


Store in the refrigerator. Do not freeze.

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.

Throw away used needles in a hard, closed container that the needles cannot poke through. Keep this container away from children and pets.


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

Using interferon alfa-2b injection 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.

A negative pregnancy test is required for women who are of childbearing age before starting combination therapy with interferon alfa-2b injection and 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.

This medicine may cause serious types of allergic reactions, including anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Call your doctor right away if you have itching, hives, hoarseness, trouble breathing, trouble swallowing, or any swelling of your hands, face, mouth, or throat.

Interferon alfa-2b injection can temporarily lower the number of white blood cells in your blood, increasing 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.

This medicine can increase thoughts of suicide in people with or without a history of a mental illness. This medicine may also cause relapse in people with a history of substance abuse. Tell your doctor right away if you start to feel more depressed or exhibit aggressive behavior. Also tell your doctor right away if you have thoughts of hurting yourself or others. Report any unusual thoughts or behaviors that trouble you, especially if they are new or get worse quickly. Make sure your caregiver knows if you have trouble sleeping, get upset easily, have a big increase in energy, or start to act reckless. Also tell your doctor if you have sudden or strong feelings, such as feeling nervous, angry, restless, violent, or scared. If you, your child, or your caregiver notice any of these side effects during treatment and up to 6 months after treatment, tell your doctor right away.

The powder form of this medicine contains albumin, which comes from human blood. Some human blood products have transmitted certain viruses to people who have received them, although the risk is low. Human donors and donated blood are both tested for viruses to keep the transmission risk low. Talk with your doctor about this risk if you have questions.

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

Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, unusual tiredness or weakness, or yellow eyes or skin. These could be symptoms of a serious liver problem.

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.

Interferon alfa-2b injection and ribavirin combination may cause a dry mouth. For temporary relief of mouth dryness, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if your mouth continues to feel dry for more than 2 weeks, check with your medical doctor or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.

Some patients who have used this medicine with ribavirin have had vomiting. If you vomit during or after your treatment, rinse your mouth out with water. This may also help prevent damage to your teeth and gums.

Children who use interferon alfa-2b and ribavirin combination may have weight loss and slowed growth. Most children have a growth spurt and gain weight after therapy ends. If you have questions about this, talk to your doctor.

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.

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

  1. Depression
  2. difficult or labored breathing
  3. swelling or puffiness of the face
  4. tightness in the chest
  5. weight loss

Less common

  1. Back, leg, or stomach pains
  2. bleeding, tender, or enlarged gums
  3. bloody, black, or tarry stools
  4. bloody nose
  5. bloody or cloudy urine
  6. blurred vision
  7. change in personality
  8. changes in behavior
  9. chest pain, discomfort, or heaviness
  10. chills
  11. clay-colored stools
  12. confusion as to time, place, or person
  13. constipation
  14. cough producing mucus
  15. coughing or spitting up blood
  16. dark urine
  17. decreased urination
  18. diarrhea
  19. difficult or painful urination
  20. dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  21. drowsiness
  22. fainting
  23. fast, slow, pounding, irregular, or racing heartbeat or pulse
  24. feeling, seeing, or hearing things that are not there
  25. feeling that others are watching you or controlling your behavior
  26. feeling that others can hear your thoughts
  27. fever
  28. hallucinations
  29. headache
  30. hearing loss
  31. heavier menstrual periods
  32. hives or rash
  33. hoarseness or husky voice
  34. inability to speak
  35. increased thirst
  36. increased urination
  37. indigestion
  38. irritability
  39. itching, pain, redness, or swelling of the skin
  40. light-colored stools
  41. lightheadedness
  42. loss of appetite
  43. loss of consciousness
  44. loss of hearing
  45. lower back or side pain
  46. metallic taste
  47. muscle aches or cramps
  48. nausea or vomiting
  49. pale skin
  50. passing of gas
  51. pinpoint red spots on the skin
  52. seizures
  53. severe mood or mental changes
  54. severe stomach pain with nausea and vomiting
  55. slow speech
  56. sneezing
  57. sores, ulcers, or white spots on the lips or tongue or inside the mouth
  58. stiffness of the limbs
  59. stomach cramps, tenderness, or discomfort
  60. stomach pain, continuing
  61. stomach upset
  62. sweating
  63. swelling around the eyes
  64. swelling of the face, fingers, hands, ankles, feet, or lower legs
  65. swollen, painful, or tender lymph glands in the neck, armpit, or groin
  66. thoughts of hurting or killing oneself
  67. trouble sleeping
  68. unusual behavior
  69. unusual bleeding or bruising
  70. unusual tiredness or weakness
  71. weight gain
  72. yellowing of the eyes or skin

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

  1. Acid or sour stomach
  2. bleeding gums
  3. blistering, crusting, irritation, itching, or reddening of the skin
  4. body aches or pain
  5. burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  6. change in taste, or bad, unusual, or unpleasant (after) taste
  7. cracked, dry, or scaly skin
  8. hair loss or thinning of the hair
  9. irritation in the mouth
  10. joint pain
  11. lack or loss of strength
  12. loss of memory
  13. muscle or bone pain
  14. pain or tenderness around the eyes and cheekbones
  15. poor concentration
  16. problems with memory
  17. redness and swelling of the gums
  18. stuffy or runny nose
  19. swollen joints

Less common

  1. Abnormal ejaculation
  2. absent, missed, or irregular menstrual periods
  3. bleeding, burning, inflammation, itching, or pain at the injection site
  4. bone deformity
  5. burning, itching, and pain in the hairy areas, pus at the root of the hair
  6. burning, numbness, pain, or tingling in all fingers except smallest finger
  7. cold and clammy skin
  8. decrease in height
  9. decreased interest in sexual intercourse
  10. degenerative disease of the joint
  11. difficulty with moving or walking
  12. discoloration of the skin
  13. inability to have or keep an erection
  14. increased clear or white vaginal discharge
  15. increased sensitivity of the skin to sunlight
  16. itching or pain of the genital area
  17. leg cramps
  18. longer menstrual periods
  19. loss in sexual ability, desire, drive, or performance
  20. multiple swollen and inflamed skin lesions
  21. pain in the ankles or knees
  22. pain in the ribs
  23. pain, inflammation, or swelling in the calves, shoulders, or hands
  24. painful, red lumps under the skin, mostly on the legs
  25. pelvic pain
  26. rash with flat lesions or small raised lesions on the skin
  27. red or irritated eyes
  28. redness or swelling in the arms or legs
  29. redness, tenderness, itching, burning, or peeling of the skin
  30. severe sunburn
  31. shivering
  32. skin rash, encrusted, scaly, and oozing small lumps under the skin
  33. small lumps under the skin
  34. soreness of the muscles
  35. stopping of menstrual bleeding
  36. swelling or redness in the joints
  37. tanning or blue-gray discoloration of the skin
  38. tearing of the eyes
  39. underactive reflexes
  40. unexpected menstrual bleeding

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.