Intron A

By Medically reviewed by hellodoktor

Generic Name: Intron A Brand Name(s): Generics only. No brands available.


What is Intron® A (interferon alfa-2b) used for?

Intron® A is commonly used for the treatment of various cancers (e.g., leukemia, melanoma, AIDS-related Kaposi’s sarcoma).

It is also used to treat virus infections (e.g., chronic hepatitis B, chronic hepatitis C, condylomata acuminata).

This medication is the same as a protein that your body naturally produces (interferon). In the body, it is thought to work by affecting cell function/growth and the body’s natural defenses (immune system) in many ways. Adding more interferon may help your body fight off cancer or virus infections.

How should I take Intron® A (interferon alfa-2b)?

This medication is given by injection into a muscle or under the skin as directed by your doctor. Rotate the injection site each time you inject this medication to prevent soreness. It may also be given by injection into a vein or directly into a lesion, usually by a health care professional.

If you are giving this medication to yourself at home, learn all preparation and usage instructions from your health care professional. Do not shake the medication container (vial or syringe). Doing so may decrease the effectiveness of the drug. Before using, check this product visually for particles or discoloration. If either is present, do not use the liquid. Learn how to store and discard medical supplies safely. Never reuse single-use syringes or needles. It is okay to reuse the multidose pen. It is best used in the evening before bedtime to reduce side effects.

Drink plenty of fluids while using this medication unless otherwise directed by your doctor.

How do I store Intron® A (interferon alfa-2b)?

Intron® A is best stored in the refrigerator. To prevent drug damage, do not freeze. There may be different brands of Intron® A that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush Intron® A down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using Intron® A (interferon alfa-2b)?

This drug may make you dizzy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages.

Do not have immunizations/vaccinations without the consent of your doctor, and avoid contact with people who have recently received oral polio vaccine or flu vaccine inhaled through the nose. Wash your hands well to prevent the spread of infections.

To lower your risk of getting cut, bruised, or injured, use caution with sharp objects like razors and nail cutters, and avoid activities such as contact sports.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Children may be more sensitive to the side effects of this drug, especially mental/mood changes (such as severe depression, thoughts/attempts of suicide). Interferon and ribavirin may also slow down a child’s rate of growth. Normal weight gain and rate of growth usually return after treatment is completed but the final adult height may be lower than expected. Monitor your child’s height and weight periodically during treatment.

Caution is advised when using this drug in the elderly because they may be more sensitive to the effects of the drug, especially dizziness, mental/mood changes, and effects on the heart.

If you are having surgery, including dental surgery, tell the doctor or dentist that you are receiving Intron® A.

Is it safe during pregnancy or breastfeeding?

There are no adequate studies in women for determining risk when using this medication during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking this medication. This medication is pregnancy risk category C, according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk
  • B=No risk in some studies
  • C=There may be some risk
  • D=Positive evidence of risk
  • X=Contraindicated
  • N=Unknown

Side effects

What side effects can occur from Intron® A (interferon alfa-2b)?

When using this drug, some common side effects may occur:

  • Injection site reactions (pain/swelling/redness)
  • Headache
  • Tiredness
  • Diarrhea
  • Upset stomach
  • Loss of appetite
  • Back pain
  • Dizziness
  • Dry mouth
  • Taste changes
  • Nausea
  • Vomiting
  • Flu-like symptoms (such as fever, chills, and muscle aches)
  • Tooth and gum problems
  • Temporary hair loss

Tell your doctor right away if you have any serious side effects, including:

  • Feeling too hot or cold (more than others around you)
  • Fast/irregular heartbeat
  • Increased thirst/urination
  • Menstrual changes (absent/delayed/irregular periods)
  • Numbness/tingling of hands/feet
  • Swelling (especially of face/hands/feet)
  • Trouble sleeping
  • Trouble walking
  • Vision changes (such as blurred vision, partial loss of vision)
  • Easy bleeding/bruising
  • Persistent nausea/vomiting
  • Signs of infection (e.g., fever, persistent sore throat)
  • Stomach/abdominal pain
  • Dark urine
  • Black/tarry stools
  • Yellowing eyes/skin

Get medical help right away if any of these very serious side effects occur including chest pain, seizures, weakness on one side of the body, slurred speech.

This drug may cause you to develop serious mental/mood changes that may get worse during treatment or after your last dose. Tell your doctor right away if you have symptoms such as confusion, depression, thoughts of suicide or hurting others, unusual irritability, or aggressive behavior. If this occurs, psychiatric therapy and monitoring is recommended during and after treatment with this medication.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.


What drugs may interact with Intron® A (interferon alfa-2b)?

Intron® A may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Some products that may interact with this drug include:

  • Barbiturates (e.g., phenobarbital)
  • Colchicine
  • Drugs affecting your immune system (e.g., cancer chemotherapy, aldesleukin, cyclosporine)
  • Hydroxyurea
  • Telbivudine
  • Theophyllines (e.g., aminophylline, theophylline)

Does food or alcohol interact with Intron® A (interferon alfa-2b)?

Intron® A may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with Intron® A (interferon alfa-2b)?

Intron® A may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

These health conditions may include:

  • An organ transplant (surgery to replace an organ in the body)
  • Anemia (low red blood cells) or low white blood cells
  • Bleeding problems or blood clots including a pulmonary embolism (PE; a blood clot in the lung)
  • A lung disease such as pneumonia, pulmonary arterial hypertension (PAH; high blood pressure in the vessels carrying blood to the lungs, causing shortness of breath, dizziness, and tiredness)
  • Chronic obstructive pulmonary disease (COPD; a group of diseases that affect the lungs and airways)
  • Eye problems
  • Blood cell disorders (e.g., anemia, neutropenia, thrombocytopenia)
  • Cancer
  • Diabetes
  • Heart disease (e.g., angina, irregular heartbeat)
  • High blood pressure
  • HIV infection
  • Immune system diseases (e.g., lupus, psoriasis, rheumatoid arthritis)
  • Intestinal disease (e.g., colitis)
  • Kidney disease
  • Liver disease (e.g., autoimmune hepatitis, decompensated liver disease)
  • Mental/mood disorders (e.g., anxiety, depression)
  • High blood triglyceride levels
  • Pancreatitis
  • Seizure disorder
  • Thyroid disease
  • Use/abuse of drugs/alcohol


The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using Intron® A (interferon alfa-2b).

What is the dose of Intron® A (interferon alfa-2b) for an adult?


Inject the medication either subcutaneously or intramuscularly three times a week.


Inject the medication either subcutaneously or intramuscularly three times a week, usually for 16 weeks.

Hairy cell leukemia

Inject the medication either intramuscularly or subcutaneously 3 times a week for up to 6 months.

Malignant melanoma

Inject the medication intravenously for 5 consecutive days for 4 weeks, then subcutaneously three times per week for 48 weeks.

Follicular melanoma

Inject the medication subcutaneously three times per week for up to 18 months.

Genital warts

Inject the medication intravenously three times weekly on alternate days for 3 weeks, then treatment may be continued for up to 16 weeks.

Kaposi’s sarcoma

Inject the medication either subcutaneously or intramuscularly three times a week for 16 weeks.

What is the dose of Intron® A (interferon alfa-2b) for a child?

The dosage has not been established in pediatric patients. It may be unsafe for your child. It is always important to fully understand the safety of the drug before using. Please consult with your doctor or pharmacist for more information.

How is Intron® A (interferon alfa-2b) available?

Intron® A is available in the following dosage forms and strengths:

Injectable solution

  • 6 million International Units/ml (3.8mL vial)
  • 10 million International Units/ml (3.2mL vial)

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of Intron® A, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: March 25, 2017 | Last Modified: September 13, 2019

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