Interferon Alfa-2b

Reviewed on 6/27/2022

What Is Interferon Alfa 2b and How Does It Work?

Interferon Alfa 2b is a prescription medication used to treat the symptoms of Hairy Cell Leukemia, Malignant Melanoma, Follicular Lymphoma, Condylomata Acuminata, AIDS-related Kaposi’s Sarcoma, Chronic and Acute Hepatitis C, and Chronic Hepatitis B. 

What Are Dosages of Interferon Alfa 2b?

Adult and pediatric dosage

Injectable solution

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

Multidose pen; 6 doses each

  • 22.5 million International Units/1.5 mL
  • 37.5 million International Units/1.5 mL
  • 75 million International Units/1.5 mL

Powder for injection

  • 10 million International Units/vial
  • 18 million International Units/vial
  • 50 million International Units/vial

Hairy Cell Leukemia

Adult dosage

  • 2 million Units/m² IM/SC 3 times/week for up to 6 months  
  • If severe adverse reaction (ADR) develops: reduce the dose by 50% or temporarily withhold, THEN
  • Resume at 50% after ADRs abate: 1 million Units/m² Intramuscular/Subcutaneous 3 times/week

Malignant Melanoma

Adult dosage

  • Induction 20 million Units/m² Intravenous over 20 min, 5 days per week for 4week  
  • Maintenance dose: 10 million Units/m² Subcutaneous 3 times per week for 48week
  • Withhold treatment if ANC below 500/mm³ or ALT/AST above 5 times the upper limit of normal (ULN); re-start at 50% previous dose

Follicular Lymphoma

Adult dosage

  • 5 million units 3 times/week for up to 18 months in conjunction with anthracycline-containing combination chemotherapy in patients above18 years old

Condylomata Acuminata

Adult dosage 

  • 1 million units injected into each lesion 3 times/week once a day for 3week
  • May repeat the course if unsatisfactory results 12-16 weeks after initial treatment
  • Max 5 lesions/single course of treatment
  • Do not use the 18 or 50 million Units of Powder for injection
  • Do not use the 18 million Units of multidose Intron A solution for injection

AIDS-related Kaposi's Sarcoma

Adult dosage

  • 30 million Units/m² Intramuscular/Subcutaneous 3 times/week for 16week  
  • Dose reduction frequently required: See Mfr's PI

Chronic Hepatitis B

Adult dosage

  • 30-35 million Units Subcutaneous/Intramuscular per week, either as 5 million Units once a day or 10 million Units 3 times/week for 16week
  • Reduce 50%: WBC below1.5 x 10^9/L; Granulocyte below0.75 x 10^9/L; platelets below50 x 10^9/L
  • Discontinue permanently: WBC below 1.0 x 10^9/L; Granulocyte below0.5 x 10^9/L; platelet below 25 x 10^9/L

Pediatric dosage

  • 3 million Units/m² Intramuscular /Subcutaneous 3 times/week for 1 week; increase to 6 million U/m² 3 times/week Subcutaneous for 16-24 weeks; not to exceed 10 million units/dose 3 times/week  

Chronic Hepatitis C

Adult dosage

  • 3 million units Intramuscular/Subcutaneous 3 times/week for16 week
  • If ALT normalized after 16 weeks, continue treatment for 18-24 months
  • If ALT is not normalized or high levels of HCV RNA after 16 weeks, consider discontinuing treatment

Acute Hepatitis C

Adult dosage

  • 5 million Units Subcutaneous/Intramuscular once a day for 4 weeks, then 3 times/week for 20 week
  • If severe adverse reactions develop reduce the dose by 50% or temporarily withhold until adverse reactions abate

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Are Side Effects Associated with Using Interferon Alfa 2b?

Common side effects of Interferon Alfa 2b include:

  • flu-like symptoms,
  • headache,
  • tiredness,
  • nausea,
  • diarrhea,
  • loss of appetite,
  • thinning hair, and
  • swelling, pain, or burning at the injection site.

Serious side effects of Interferon Alfa 2b include:

  • hives,
  • difficulty breathing,
  • swelling of the face, lips, tongue, or throat,
  • skin rash with blistering and peeling,
  • anxiety,
  • chest pain,
  • new or worsening cough,
  • fever,
  • depression,
  • irritability,
  • confusion,
  • thoughts about self-harm,
  • falling back into a previous pattern of drug addiction,
  • vision changes,
  • problems with the teeth,
  • severe stomach pain with bloody diarrhea,
  • sudden numbness or weakness (especially on one side of the body),
  • slurred speech,
  • problems with balance,
  • chest pain or pressure,
  • fast heartbeats,
  • sweating,
  • light-headedness,
  • skin problems,
  • joint pain or swelling,
  • cold feeling,
  • pale appearance in the fingers or toes,
  • chills,
  • body aches,
  • cough with yellow or pink mucus,
  • pain or burning while urinating,
  • loss of appetite,
  • upper stomach pain (may spread to the back),
  • nausea,
  • vomiting,
  • dark urine, and
  • yellowing of the skin or eyes (jaundice)

Rare side effects of Interferon Alfa 2b include:

  • none 

Seek medical care or call 911 at once if you have the following serious side effects:

  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in your chest; shortness of breath; and sudden dizziness, lightheartedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Interferon Alfa 2b?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Interferon Alfa 2b has no noted severe interactions with any other drugs.
  • Interferon Alfa 2b has serious interactions with the following drugs:
    • deferiprone
    • palifermin
    • pexidartinib
    • pretomanid
    • ropegInterferon Alfa 2b
  • Interferon Alfa 2b has moderate interactions with the following drugs:
  • Interferon Alfa 2b has minor interactions with the following drug:

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Interferon Alfa 2b?


  • Hypersensitivity 
  • Autoimmune hepatitis
  • Decompensated liver disease (Child-Pugh below 6 [class B and C])
  • Contraindications for combination therapy with ribavirin:
  • Pregnant women and men whose female partners are pregnant.
  • Hemoglobinopathies (e.g., thalassemia major, sickle-cell anemia)
  • Creatinine clearance less than 50 mL/min

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Interferon Alfa 2b?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Interferon Alfa 2b?”


  • Life-threatening or fatal neuropsychiatric events, including suicide, suicidal and homicidal ideation, depression, relapse of drug addiction/overdose, and aggressive behavior sometimes directed towards others reported in patients with and without a previous psychiatric disorder during therapy and follow-up; psychoses, hallucinations, bipolar disorders, and mania have been observed in patients treated with interferon-alpha should be used with caution in patients with a history of psychiatric disorders; discontinue if severe depression develops
  • If psychiatric symptoms persist or worsen, or suicidal or homicidal ideation or aggressive behavior towards others identified, discontinue therapy and follow the patient closely, with psychiatric intervention as appropriate; narcotics, hypnotics, or sedatives may be used concurrently with caution and patients should be closely monitored until adverse effects resolved
  • Dyspnea, pulmonary infiltrates, pneumonia, bronchiolitis obliterans, interstitial pneumonitis, pulmonary hypertension, and sarcoidosis, some resulting in respiratory failure or patient deaths, may be induced or aggravated by therapy; recurrence of respiratory failure has been observed with interferon rechallenge; monitor
  • Development or exacerbation of autoimmune disorders (e.g., thyroiditis, thrombotic thrombocytopenic purpura, idiopathic thrombocytopenic purpura, rheumatoid arthritis, interstitial nephritis, systemic lupus erythematosus, and psoriasis) observed; use with caution in patients with autoimmune disorders
  • Caution in pre-existing cardiac abnormalities &/or advanced cancer Ischemic and hemorrhagic cerebrovascular events reported
  • Pancreatitis and ulcerative or hemorrhagic/ischemic colitis may occur
  • Severe decreases in neutrophil or platelet counts reported
  • Hepatitis C (CHC) patients with cirrhosis may be at risk of hepatic decompensation and death when treated with alpha interferons, including peginterferon alpha 2b; cirrhotic CHC patients co-infected with HIV receiving highly active antiretroviral therapy (HAART) and alpha interferons with or without ribavirin appear to be at increased risk for development of hepatic decompensation compared to patients not receiving HAART; monitor clinical status and hepatic function during treatment and discontinue immediately if decompensation (Child-Pugh score greater than 6) observed
  • Monitor patients with impaired renal function, for signs and symptoms of interferon toxicity, including increases in serum creatinine; adjust the dose or discontinue therapy accordingly
  • Serious, acute hypersensitivity reactions and cutaneous eruptions reported
  • Dental/periodontal disorders reported with combination therapy Hypertriglyceridemia may result in pancreatitis (e.g., triglycerides greater than 1000 mg/dL)
  • Weight loss and growth inhibition reported during combination therapy in pediatric patients
  • Long-term growth inhibition (height) was reported in some patients
  • Peripheral neuropathy was observed when used in combination with telbivudine
  • Risk of visual impairment and retinal disorders; discontinue if ophthalmologic problems develop
  • Use with caution in patients with the endocrine disorder: thyroid disease; DM prone to ketoacidosis
  • Pre-existing cardiac abnormalities &/or advanced cancer
  • AIDS-related Kaposi's Sarcoma: do not use in patients w/ rapidly progressive disease
  • Discontinue if acute hypersensitivity occurs
  • Risk of exacerbation of pre-existing psoriasis & sarcoidosis; risk of developing new sarcoidosis
  • Patients should be well hydrated during initial treatment
  • If platelets are below 50,000/mm³, do not administer IM (may admin SC)
  • Do not use the 18 million IU or 50 million IU powder for injection or the18 million IU multidose vial for condylomata acuminata
  • Increases risk of hepatic decompensation and death in patients with cirrhosis; any patient developing liver function abnormalities during treatment should be monitored closely and if appropriate, treatment should be discontinued
  • Numerous cardiotoxicities, including arrhythmias, ischemia, infarction, and cardiomyopathy occur during and immediately after infusion

Pregnancy & Lactation

  • Use with caution if the benefits outweigh the risks during pregnancy.
  • Lactation
    • Unknown

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