Interferon Alfa: Uses & Side Effects

Interferon alfa is a family of proteins and glycoproteins with antiviral, antineoplastic, and immunomodulating activities. Available in America as interferon alfa-2b and interferon alfa-n3. Also available covalently bound to monomethoxy polyethylene glycol (PEG) (i.e., peginterferon alfa).

Uses for Interferon Alfa

Chronic HBV Infection

Interferon alfa-2b: Treatment of chronic HBV infection in adults, adolescents, and children ≥1 year of age with compensated liver disease.

Goal of antiviral therapy is sustained suppression of HBV replication and remission of liver disease; long-term goal is prevention of cirrhosis, hepatic failure, and hepatocellular carcinoma.

Currently available therapies (e.g., interferon alfa, peginterferon alfa, adefovir, entecavir, lamivudine, telbivudine, tenofovir) do not eradicate HBV and may have only limited long-term efficacy. When making decisions regarding treatment, consider patient’s age, severity of liver disease, likelihood of response, safety and efficacy of the drug, potential for selection of resistant HBV strains, potential for adverse reactions, costs, patient’s pregnancy potential, and patient and provider preferences.

American Association for the Study of Liver Diseases (AASLD) states that drugs of choice for initial treatment of chronic HBV infection in patients with compensated liver disease are peginterferon alfa, entecavir, or tenofovir, unless contraindicated or ineffective. Efficacy of peginterferon alfa and nonconjugated interferon alfa are considered similar, but peginterferon alfa dosage schedule more convenient and generally preferred.

Treatment of chronic HBV infection is complex and rapidly evolving and should be directed by clinicians familiar with the disease; consult specialist to obtain the most up-to-date information.

Chronic HCV Infection

Interferon alfa-2b: Has been used for treatment of chronic HCV infection in adults with compensated liver disease; used alone or in conjunction with oral ribavirin.

Interferon alfa-2b: Has been used for treatment of chronic HCV infection in treatment-naive children ≥3 years of age with compensated liver disease; used in conjunction with oral ribavirin.

Peginterferon alfa (not interferon alfa) recommended if an interferon is used for treatment of chronic HCV infection. Interferon alfa alone or in conjunction with oral ribavirin associated with lower response rates than peginterferon alfa in conjunction with oral ribavirin.

Treatment of chronic HCV infection is complex and rapidly evolving; consult a specialist to obtain the most up-to-date information.

Chronic HDV Infection

Interferon alfa: Has been used with some limited success for treatment of chronic HDV infection in adults and children coinfected with HBV. Although interferon alfa may suppress viral activity in some patients, sustained response not obtained and relapse generally occurs after drug discontinued.

HDV infection only occurs in individuals with HBV infection since the virus depends on HBV for production of envelope proteins. Can be acquired as a coinfection with HBV or as a superinfection in HBV carriers. HDV superinfection in HBV carriers almost always results in chronic infection with both viruses and is associated with high risk of cirrhosis, hepatic decompensation, and hepatocellular carcinoma.

Human Papillomavirus (HPV) Infections

Interferon alfa-2b, interferon alfa-n3: Intralesional treatment of external genital and perianal exophytic warts (condylomata acuminata) caused by HPV.

CDC states that intralesional interferon alfa is an alternative (not preferred) option for treatment of external HPV warts because of higher frequency of adverse effects (including rare severe systemic adverse effects) and/or less efficacy data compared with other options.

No currently available option has been shown to eradicate HPV infectivity.

West Nile Virus Infection

Interferon alfa-2b, interferon alfa-n3: Have been investigated for treatment of serious West Nile virus (WNV) infection.

Despite initial case reports suggesting some clinical benefits in neuroinvasive disease, efficacy not proven in controlled clinical trials. Unlikely to inhibit WNV replication following establishment of infection.

Hairy Cell Leukemia

Interferon alfa-2b: Treatment of hairy cell leukemia (leukemic reticuloendotheliosis).

Complete response achieved in 10% of patients and overall response achieved in approximately 80% of patients.

An alternative for hairy cell leukemia; cladribine or pentostatin preferred (achieve higher complete response rates than interferon alfa).

AIDS-related Kaposi’s Sarcoma

Interferon alfa-2b: Palliative treatment of AIDS-related Kaposi’s sarcoma in selected adults (designated an orphan drug by FDA for this indication).

Do not use in patients with rapidly progressive visceral or life-threatening disease; response generally is slow and poor.

Likelihood of response to interferon alfa is greater in patients without systemic symptoms who have limited lymphadenopathy and relatively intact immune systems as indicated by CD4+ T-cell counts.

All patients with AIDS-related Kaposi’s sarcoma should be receiving highly active antiretroviral therapy; in some patients, initiation of antiretroviral therapy alone may result in tumor regression and resolution of lesions.

Non-Hodgkin’s and Cutaneous T-cell Lymphomas

Interferon alfa-2b: Although labeled by FDA for use in conjunction with an anthracycline for initial treatment of clinically aggressive follicular non-Hodgkin’s lymphoma in adults, other agents preferred.

Efficacy in patients with low-grade, low-tumor-burden follicular non-Hodgkin’s lymphoma not demonstrated.

Interferon alfa: Has been used for treatment of cutaneous T-cell lymphomas.


Interferon alfa-2b: Used as an adjunct to surgery (within 56 days of surgery) in adults with malignant melanoma who are disease free but at high risk for systemic recurrence.

Palliative treatment of metastatic melanoma in selected patients, alone and in conjunction with other therapies (e.g., radiation).

Basal Cell and Squamous Cell Skin Cancers

Interferon alfa: Has been used intralesionally for treatment of basal cell carcinoma and squamous cell carcinoma.

Chronic Myelogenous Leukemia

Interferon alfa-2b: Has been used for treatment of adult-type (Philadelphia chromosome-positive) chronic myelogenous (myelocytic, myeloid) leukemia (CML).

Renal Cell Carcinoma

Interferon alfa: Has been used for treatment of metastatic renal cell carcinoma in selected patients.

Bladder Cancer

Interferon alfa: Has been used intravesically for prophylaxis or treatment of superficial bladder cancer.

Ovarian Cancer

Interferon alfa: Has been used intraperitoneally for treatment of minimal residual epithelial ovarian cancer in a limited number of patients.


Interferon alfa-2a (Intron A): Known hypersensitivity (e.g., urticaria, angioedema, bronchoconstriction, anaphylaxis) to interferon alfa or any ingredient in the formulation.

Interferon alfa-n3 (Alferon N): Known hypersensitivity to human interferon alfa proteins or any component in the formulation; history of anaphylactic reactions to murine (mouse) IgG, egg protein, or neomycin.

Interferon alfa-2b: Autoimmune hepatitis or hepatic decompensation (Child-Pugh score >6, class B and C).

Interferon alfa-2b: Concomitant use of oral ribavirin contraindicated in women who are or may become pregnant, men whose female partners are pregnant, patients with known hypersensitivity to ribavirin or any ingredient in the formulation, patients with hemoglobinopathies (e.g., thalassemia major, sickle cell anemia), and patients with Clcr <50 mL/minute.

Common Adverse Effects

  • Flu-like symptoms (e.g., fever, headache, chills, myalgia/arthralgia, fatigue, increased sweating, asthenia, rigors, dizziness)
  • Abdominal pain
  • Alopecia
  • Anemia
  • Anorexia
  • Back pain
  • Depression
  • Diarrhea
  • Dyspnea
  • Musculoskeletal pain
  • Nausea
  • Neutropenia
  • Pharyngitis
  • Somnolence
  • Vomiting
  • Weight loss

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Keywords: interferon alfa; interferon alfa-2b; interferon alfa-n3.

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.