Skip to Content

Interferon alfa-n3 Side Effects

In Summary

Commonly reported side effects of interferon alfa-n3 include: fever, headache, myalgia, arthralgia, flu-like symptoms, vomiting, and chills. Other side effects include: back pain. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to interferon alfa-n3: injection solution

What are some side effects that I need to call my doctor about right away?

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:

  • 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.
  • Very bad dizziness or passing out.
  • Chest pain or pressure.
  • Blurred eyesight.
  • Low white blood cell counts have rarely happened with this drug. This may lead to a higher chance of getting an infection. Tell your doctor if you have ever had a low white blood cell count. Call your doctor right away if you have signs of infection like fever, chills, or sore throat.

What are some other side effects of this drug?

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:

  • Dizziness.
  • Muscle or joint pain.
  • Back pain.
  • Not able to sleep.
  • Feeling tired or weak.
  • Feeling sleepy.
  • Irritation where the shot is given.
  • Upset stomach or throwing up.
  • Loose stools (diarrhea).
  • Mouth irritation or mouth sores.
  • Flu-like signs. These include headache, weakness, fever, shakes, aches, pains, and sweating. Mild pain drugs may help.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects at

For Healthcare Professionals

Applies to interferon alfa-n3: injectable solution


Side effects were evaluated in 202 patients with condylomata acuminata receiving interferon alfa-n3 by intralesional administration and in 31 patients with cancer receiving interferon alfa-n3 by systemic administration.

Most of the systemic side effects reported in patients with condylomata acuminata were mild or moderate. Severe systemic side effects were reported in 18% of patients treated with interferon alfa-n3 and 13% of patients treated with placebo. The severe systemic side effects reported were influenza-like symptoms (most common), back pain, insomnia, and sensitivity to allergens.

The occurrence of side effects in patients with cancer was determined to be unrelated to the intramuscular dose of interferon alfa-n3.[Ref]


Musculoskeletal side effects have included myalgias (45%), arthralgia (5%), back pain (4%), and muscle cramps (1%). Myalgias (16%; severe: 13%), arthralgia (10%; severe: 3%), and muscle soreness (severe: 3%) have been reported in patients with cancer.[Ref]


Other side effects have included fever (40%), influenza-like symptoms (including myalgias, fever, and/or headache; 30%), chills (14%), fatigue (14%), malaise (9%), and sweating (2%)., Left groin lymph node swelling, thirst, hot sensation on bottom of feet, heat intolerance, hot flashes, throat tightness, and decrease in concentration have been reported in 1% of patients. Chills (87%; severe: 45%), fever (81%; severe: 55%), anorexia (68%; severe: 45%), malaise (65%; severe: 54%), chest pains (10%; severe: 6%), fatigue (6%; severe: 6%), stiff shoulders (severe: 3%), sweating (severe: 3%), flushed face, edema, shakes/shivers, and cramps have been reported in patients with cancer.[Ref]

Nervous system

Nervous system side effects have included headache (31%), dizziness (9%), insomnia (2%), vasovagal reaction (2%), tongue hyperesthesia (1%), and tingling of legs/feet (1%). Sleepiness (10%; severe: 3%), headache (10%; severe: 3%), numbness (severe: 3%), confusion (severe: 3%), lightheadedness (severe: 3%), numbness in hands, numbness in fingers, and ringing in ears have been reported in patients with cancer.[Ref]


Gastrointestinal side effects have included nausea (4%), vomiting (3%), dyspepsia/heartburn (3%), diarrhea (2%), strange taste in mouth (1%), and increased salivation (1%). Nausea (48%; severe: 16%), vomiting (29%; severe: 10%), diarrhea (6%; severe: 3%), sore mouth/stomatitis (6%; severe: 6%), dry mouth, mucositis, constipation, and upset stomach have been reported in patients with cancer.[Ref]


Hematologic side effects have included decreased white blood cells (11%). Abnormal hemoglobin level (7%), white blood cell count (3%), and platelet count (3%) have been reported in patients with cancer.


Dermatologic side effects have included generalized pruritus (2%), papular rash on neck (1%), photosensitivity (1%), and herpes labialis (1%).[Ref]


Psychiatric side effects have included depression (2%) and nervousness (1%). Depression (severe: 3%) has been reported in patients with cancer.[Ref]


Respiratory side effects have included nose/sinus drainage (2%), pharyngitis (1%), and nosebleed (1%). Coughing has been reported in patients with cancer.[Ref]


Local side effects have included application site disorders (such as itching and pain) in 12% of patients treated with interferon alfa-n3 and 26% of patients treated with placebo. Soreness at injection site (10%) has been reported in patients with cancer.[Ref]


Ocular side effects have included visual disturbances (1%). Blurred vision (6%; severe: 3%) and pain on ocular rotation (severe: 3%) have been reported in patients with cancer.[Ref]


Genitourinary side effects have included dysuria (1%).[Ref]


Immunologic side effects have included swollen lymph nodes (1%).[Ref]


Cardiovascular side effects have included low blood pressure (6%; severe: 6%) in patients with cancer.


Metabolic side effects have included abnormal alkaline phosphatase (8%) in patients with cancer.


1. "Product Information. Alferon N injection (interferon alfa-2a)" Interferon Sciences Inc, New Brunswick, NJ.

Some side effects of interferon alfa-n3 may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.