What are the most common side effects?

A flu-like syndrome (fever, chills, muscle aches, fatigue) is very common, along with low blood counts, depression, thyroid problems, and liver-enzyme elevations.

Can I use it for research or self-experimentation?

No. It is a prescription-only biologic with serious risks and must be prescribed, dosed, and monitored by a qualified physician; this page is educational and not medical advice.

EMA-approvedaka Intron A

Interferon alfa-2b — Complete Research Guide (2026)

Q: What is it approved to treat?

Approvals have included hairy-cell leukaemia, adjuvant high-risk melanoma, follicular lymphoma, AIDS-related Kaposi sarcoma, condylomata acuminata, and chronic hepatitis B and C, though newer drugs have replaced it for several of these.

Q: Does it carry a boxed warning?

Yes. The FDA boxed warning states it may cause or worsen fatal or life-threatening neuropsychiatric, autoimmune, ischaemic, and infectious disorders, requiring close medical monitoring.

Last updated 2026-06-30

TL;DR

Interferon alfa-2b (also known as Intron A) is a peptide catalogued under Immune (IFN-α). Neutral reference entry; EU status: EU-approved prescription medicine.

What is Interferon alfa-2b?

Interferon alfa-2b (brand name Intron A) is a recombinant human interferon-alpha protein, not a small peptide, produced in E. coli and used as an immunomodulatory and antiviral biologic. It holds long-standing regulatory approvals (FDA/EMA) across oncology and hepatology, including hairy-cell leukaemia, adjuvant high-risk melanoma, follicular non-Hodgkin lymphoma, AIDS-related Kaposi sarcoma, condylomata acuminata, and chronic hepatitis B and C.

Evidence is high-quality and human: multiple randomised controlled trials and a large melanoma pooled analysis, though it has been largely superseded by pegylated interferons and direct-acting antivirals for hepatitis.

How does Interferon alfa-2b work?

Interferon alfa-2b binds the type I interferon receptor (IFNAR1/IFNAR2), triggering JAK-STAT signalling that induces interferon-stimulated genes with antiviral, antiproliferative, and immunostimulatory effects.

It up-regulates MHC class I expression and enhances natural-killer-cell and T-cell activity against infected or malignant cells.

What does the research say about Interferon alfa-2b?

As high-dose adjuvant therapy it prolonged relapse-free and overall survival versus observation in high-risk resected cutaneous melanoma (ECOG E1684). ^[1]
It induced durable haematological remissions in hairy-cell leukaemia, one of its earliest approved oncology uses. ^[2]
Combined with ribavirin it produced substantially higher sustained virologic response rates than interferon alone in chronic hepatitis C. ^[4]

Clinical research & studies

The references below are the primary sources cited throughout this guide. Each links directly to PubMed or the regulator. Where evidence is preclinical (animal or in-vitro), that is stated rather than implied.

[1] Interferon alfa-2b adjuvant therapy of high-risk resected cutaneous melanoma: the Eastern Cooperative Oncology Group Trial EST 1684 — Kirkwood JM et al., Journal of Clinical Oncology 1996. (Randomised controlled trial (ECOG E1684))
[2] Alpha interferon for induction of remission in hairy-cell leukemia — Quesada JR et al., The New England Journal of Medicine 1984. (Prospective clinical study (case series))
[3] Treatment of chronic hepatitis C with recombinant interferon alfa. A multicenter randomized, controlled trial — Davis GL et al., The New England Journal of Medicine 1989. (Randomised controlled trial)
[4] Interferon alfa-2b alone or in combination with ribavirin as initial treatment for chronic hepatitis C. Hepatitis Interventional Therapy Group — McHutchison JG et al., The New England Journal of Medicine 1998. (Randomised controlled trial)
[5] A randomized, controlled trial of interferon alfa-2b alone and after prednisone withdrawal for the treatment of chronic hepatitis B. The Hepatitis Interventional Therapy Group — Perrillo RP et al., The New England Journal of Medicine 1990. (Randomised controlled trial)
[6] A pooled analysis of eastern cooperative oncology group and intergroup trials of adjuvant high-dose interferon for melanoma — Kirkwood JM et al., Clinical Cancer Research 2004. (Pooled analysis of randomised trials)

Dosing context

This is not medical advice or a usage recommendation. Dosing figures are reported research context only, cited from the published literature.

Historical regimens differed sharply by indication, ranging from high-dose intravenous induction followed by subcutaneous maintenance in adjuvant melanoma to lower subcutaneous or intralesional dosing in leukaemia, lymphoma, Kaposi sarcoma, condylomata, and viral hepatitis.

This is background context only and not a dosing recommendation; interferon alfa-2b must be prescribed and monitored by a qualified physician.

Side effects & safety profile

Interferon alfa-2b carries an FDA boxed warning that it may cause or aggravate fatal or life-threatening neuropsychiatric, autoimmune, ischaemic, and infectious disorders, and patients must be monitored closely with periodic clinical and laboratory evaluations.

Very common adverse effects include a flu-like syndrome (fever, chills, myalgia, fatigue), bone-marrow suppression, depression, thyroid dysfunction, and elevated liver enzymes.

It is a prescription-only biologic requiring specialist supervision, with treatment withdrawal for severe depression, autoimmune flares, or significant cytopenias.

Stacking & combinations

In approved practice it has been combined with ribavirin for hepatitis C, but no combination or stacking with unapproved research peptides is supported by evidence and none should be inferred.

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Frequently asked questions

It is a recombinant protein (interferon-alpha), larger than a typical peptide, made in bacteria to match a naturally occurring human immune signalling molecule.

References

[1] Interferon alfa-2b adjuvant therapy of high-risk resected cutaneous melanoma: the Eastern Cooperative Oncology Group Trial EST 1684 — Kirkwood JM et al., Journal of Clinical Oncology 1996. PMID: 8558223. View sourceStudy: Randomised controlled trial (ECOG E1684)High-dose adjuvant interferon alfa-2b significantly prolonged relapse-free and overall survival versus observation in high-risk resected melanoma.
[2] Alpha interferon for induction of remission in hairy-cell leukemia — Quesada JR et al., The New England Journal of Medicine 1984. PMID: 6689734. View sourceStudy: Prospective clinical study (case series)Alpha interferon induced haematological remissions in patients with hairy-cell leukaemia, establishing an early oncology indication.
[3] Treatment of chronic hepatitis C with recombinant interferon alfa. A multicenter randomized, controlled trial — Davis GL et al., The New England Journal of Medicine 1989. PMID: 2509916. View sourceStudy: Randomised controlled trialRecombinant interferon alfa normalised serum aminotransferase levels in a significant proportion of patients with chronic hepatitis C versus untreated controls.
[4] Interferon alfa-2b alone or in combination with ribavirin as initial treatment for chronic hepatitis C. Hepatitis Interventional Therapy Group — McHutchison JG et al., The New England Journal of Medicine 1998. PMID: 9819446. View sourceStudy: Randomised controlled trialAdding ribavirin to interferon alfa-2b markedly increased sustained virologic response rates compared with interferon alfa-2b alone.
[5] A randomized, controlled trial of interferon alfa-2b alone and after prednisone withdrawal for the treatment of chronic hepatitis B. The Hepatitis Interventional Therapy Group — Perrillo RP et al., The New England Journal of Medicine 1990. PMID: 2195346. View sourceStudy: Randomised controlled trialInterferon alfa-2b induced loss of HBeAg and HBV DNA in a significant fraction of patients with chronic hepatitis B.
[6] A pooled analysis of eastern cooperative oncology group and intergroup trials of adjuvant high-dose interferon for melanoma — Kirkwood JM et al., Clinical Cancer Research 2004. PMID: 15014018. View sourceStudy: Pooled analysis of randomised trialsPooled data confirmed a consistent relapse-free survival benefit of high-dose adjuvant interferon across ECOG and intergroup melanoma trials.

This article is for educational and research purposes only. Peptides discussed here are not approved for human consumption by the FDA, EMA, or equivalent regulators outside of specific clinical contexts. Always consult a licensed medical professional before any therapeutic use.