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Interferon Alfa-n3

Medically reviewed by Last updated on Aug 10, 2020.


(in ter FEER on AL fa en three)

Index Terms

  • Interferon Alfa n3

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Solution, Injection:

Alferon N: 5,000,000 units/mL (1 mL)

Brand Names: U.S.

  • Alferon N

Pharmacologic Category

  • Interferon


Interferons interact with cells through high affinity cell surface receptors. Following activation, multiple effects can be detected including induction of gene transcription. Inhibits cellular growth, alters the state of cellular differentiation, interferes with oncogene expression, alters cell surface antigen expression, increases phagocytic activity of macrophages, and augments cytotoxicity of lymphocytes for target cells

Use: Labeled Indications

Condylomata acuminata: Intralesional treatment of refractory or recurring external condylomata acuminata (venereal or genital warts) in patients 18 years of age or older.


Hypersensitivity to human interferon alpha proteins or any component of the formulation; anaphylactic sensitivity to mouse immunoglobulin (IgG), egg protein, or neomycin.

Dosing: Adult

Condylomata acuminata: Intralesional: 250,000 units (0.05 mL) per wart twice weekly for a maximum of 8 weeks; maximum dose per treatment session: 2.5 million units (0.5 mL). Therapy should not be repeated for at least 3 months after the initial 8-week course of therapy (unless existing warts grow or new warts appear).

Dosing: Geriatric

Refer to adult dosing.


Inject into base of wart with a 30-gauge needle. For large warts, dose may be injected at several points around the outside edge of the wart (total dose: 0.05 mL/wart).


Store at 2°C to 8°C (36°F to 46°F); do not freeze or shake.

Drug Interactions

5-Aminosalicylic Acid Derivatives: May enhance the myelosuppressive effect of Myelosuppressive Agents. Monitor therapy

Aldesleukin: Interferons (Alfa) may enhance the adverse/toxic effect of Aldesleukin. In particular, risks of myocardial and renal toxicity may be increased by this combination. Management: Consider using lower doses to minimize toxicity of this combination. Only coadminister aldesleukin and interferons (alfa) in patients in whom potential benefits outweigh the risk of severe toxicity. Monitor renal and cardiac function closely if combined. Consider therapy modification

BCG (Intravesical): Myelosuppressive Agents may diminish the therapeutic effect of BCG (Intravesical). Avoid combination

Chloramphenicol (Ophthalmic): May enhance the adverse/toxic effect of Myelosuppressive Agents. Monitor therapy

Cladribine: May enhance the myelosuppressive effect of Myelosuppressive Agents. Avoid combination

CloZAPine: Myelosuppressive Agents may enhance the adverse/toxic effect of CloZAPine. Specifically, the risk for neutropenia may be increased. Monitor therapy

Deferiprone: Myelosuppressive Agents may enhance the neutropenic effect of Deferiprone. Management: Avoid the concomitant use of deferiprone and myelosuppressive agents whenever possible. If this combination cannot be avoided, monitor the absolute neutrophil count more closely. Consider therapy modification

Dipyrone: May enhance the adverse/toxic effect of Myelosuppressive Agents. Specifically, the risk for agranulocytosis and pancytopenia may be increased Avoid combination

Methadone: Interferons (Alfa) may increase the serum concentration of Methadone. Monitor therapy

Promazine: May enhance the myelosuppressive effect of Myelosuppressive Agents. Monitor therapy

Ribavirin (Oral Inhalation): Interferons (Alfa) may enhance the adverse/toxic effect of Ribavirin (Oral Inhalation). Hemolytic anemia has been observed. Monitor therapy

Ribavirin (Systemic): Interferons (Alfa) may enhance the adverse/toxic effect of Ribavirin (Systemic). Hemolytic anemia has been observed. Monitor therapy

Vitamin K Antagonists (eg, warfarin): Interferons (Alfa) may enhance the anticoagulant effect of Vitamin K Antagonists. Monitor therapy

Zidovudine: Interferons may enhance the adverse/toxic effect of Zidovudine. Interferons may decrease the metabolism of Zidovudine. Monitor therapy

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.

Adverse reaction incidence noted below is specific to intralesional administration in patients with condylomata acuminata.


Central nervous system: Headache (31%), chills (14%), fatigue (14%)

Hematologic & oncologic: Decreased white blood cell count (11%)

Neuromuscular & skeletal: Myalgia (45%)

Respiratory: Flu-like symptoms (30%; includes headache, fever, and/or myalgia; abated with repeated dosing)

Miscellaneous: Fever (40%)

1% to 10%:

Central nervous system: Malaise (9%), dizziness (9%), depression (2%), insomnia (2%), vasodepressor syncope (2%), hyperesthesia (tongue: 1%), paresthesia (1%)

Dermatologic: Diaphoresis (2%), pruritus (2%)

Endocrine & metabolic: Increased thirst (1%)

Gastrointestinal: Nausea (4%), vomiting (3%), dyspepsia (3%), diarrhea (2%), dysgeusia (1%)

Hematologic & oncologic: Adenopathy (groin: 1%)

Neuromuscular & skeletal: Arthralgia (5%), back pain (4%), muscle cramps (1%)

Ophthalmic: Visual disturbance (1%)

Respiratory: Rhinitis (2%), epistaxis (1%), pharyngitis (1%)

<1%, postmarketing, and/or case reports: Dysuria, hepatotoxicity (idiosyncratic; Chalasani 2014), hot flash, lack of concentration, nervousness, skin photosensitivity


Concerns related to adverse effects:

• Flu-like symptoms: Flu-like symptoms are common; may aggravate debilitating conditions.

• Hypersensitivity reactions: Discontinue use if signs/symptoms of hypersensitivity reactions occur (eg, urticaria, angioedema, bronchoconstriction, anaphylaxis).

Disease-related concerns:

• Bone marrow suppression: Use with caution in patients with severe myelosuppression.

• Cardiovascular disease: Use with caution in patients with preexisting cardiovascular disease (eg, unstable angina, uncontrolled CHF). In a scientific statement from the American Heart Association, interferon has been determined to be an agent that may either cause reversible direct myocardial toxicity or exacerbate underlying myocardial dysfunction (magnitude: moderate/major) (AHA [Page 2016]).

• Coagulation disorders: Use with caution in patients with coagulation disorders (eg, thrombophlebitis, pulmonary embolism, hemophilia).

• Diabetes: Use with caution in patients with diabetes with ketoacidosis.

• Pulmonary disease: Use with caution in patients with severe pulmonary disease (eg, chronic obstructive pulmonary disease).

• Seizure disorder: Use with caution in patients with seizure disorders.

Dosage form specific issues:

• Albumin: Contains albumin, which may carry a remote risk of transmitting Creutzfeldt-Jakob or other viral diseases.

• Product variability: Due to differences in manufacturing, strength, and type of interferon, do not change from one brand of interferon to another; a change in dosage may be required.

Other warnings/precautions:

• Appropriate use: Patients should be selected for therapy based on a number of factors: the locations and sizes of the lesions, past treatment and response, and the patient's ability to comply with the treatment regimen. Therapy is particularly useful for patients who have not responded satisfactorily to other treatment modalities (eg, podophyllin resin, surgery, laser or cryotherapy).

Reproductive Considerations

Menstrual irregularities have been reported; effective contraception is recommended during treatment.

Pregnancy Risk Factor C Pregnancy Considerations

Animal reproduction studies have not been conducted.

Patient Education

What is this drug used for?

• It is used to treat genital warts.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Feeling sleepy, tired, or weak

• Muscle or joint pain

• Irritation where the shot is given

• Diarrhea, upset stomach, or throwing up

• Not hungry

• Mouth irritation or mouth sores

• Flu-like signs like headache, weakness, fever, shakes, aches, pains, and sweating

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Very bad dizziness or passing out

• Chest pain or pressure

• Blurred eyesight

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine’s uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

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