Interferon, alfa (CLASS) (Injection route, intravenous route, subcutaneous route)

Brand Names:

  • Alferon N
  • Infergen
  • Intron A
  • Pegasys
  • PEG-Intron
  • Peg Intron RP
  • Roferon-A
  • Unitron Peg

Dosage Forms:

  • Solution
  • Kit
  • Powder for Solution
  • Injectable

Uses of This Medicine:

Interferons are substances naturally produced by cells in the body to help fight infections and tumors. They may also be synthetic (man-made) versions of these substances. Alpha interferons are used to treat hairy cell leukemia, malignant melanoma, and AIDS-related Kaposi's sarcoma. They are also used to treat laryngeal papillomatosis (growths in the respiratory tract) in children, genital warts, and some kinds of hepatitis.

Alpha interferons may also be used for other conditions as determined by your doctor.

Alpha interferons are available only with your doctor's prescription.

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although these uses are not included in product labeling, alpha interferons are used in certain patients with the following medical conditions:

  • Bladder cancer
  • Carcinoid tumors
  • Chronic myelocytic leukemia
  • Kidney cancer
  • Laryngeal papillomatosis (growths on larynx)
  • Lymphomas, non-Hodgkin's
  • Multiple myeloma
  • Mycosis fungoides
  • Polycythemia vera (a type of cancer of the blood)
  • Skin cancer
  • Thrombocytosis

Before Using This Medicine:


Tell your doctor if you have ever had any unusual or allergic reaction to medicines in this group or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


There is no specific information comparing use of alpha interferon for cancer or genital warts in children with use in other age groups.

Alpha interferons may cause changes in the menstrual cycle. Discuss this possible effect with your doctor.

Older adults

Some side effects of alpha interferons (chest pain, irregular heartbeat, unusual tiredness, confusion, mental depression, trouble in thinking or concentrating) may be more likely to occur in the elderly, who are usually more sensitive to the effects of alpha interferons.


Alpha interferons have not been shown to cause birth defects or other problems in humans. However, in monkeys given 20 to 500 times the human dose of recombinant interferon alfa-2a or given 90 to 180 times the usual dose of recombinant interferon alfa-2b, there was an increase in death of the fetuses.


It is not known whether alpha interferons pass into breast milk. However, because this medicine may cause serious side effects, breast-feeding may not be recommended while you are receiving it. Discuss with your doctor whether or not you should breast-feed while you are receiving alpha interferon.

Other medicines

Using medicines in this class with any of the following medicines is not recommended. Your doctor may decide not to treat you with a medication in this class or change some of the other medicines you take.

  • Rotavirus Vaccine, Live

Using medicines in this class with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Autumn Crocus
  • Bacillus of Calmette and Guerin Vaccine, Live
  • Captopril
  • Colchicine
  • Enalaprilat
  • Enalapril Maleate
  • Lamivudine
  • Measles Virus Vaccine, Live
  • Mumps Virus Vaccine, Live
  • Poliovirus Vaccine, Live
  • Rubella Virus Vaccine, Live
  • Smallpox Vaccine
  • Theophylline
  • Typhoid Vaccine
  • Varicella Virus Vaccine
  • Yellow Fever Vaccine
  • Zidovudine

Other interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other medical problems

The presence of other medical problems may affect the use of medicines in this class. Make sure you tell your doctor if you have any other medical problems, especially:

  • Bleeding problems May be worsened by recombinant interferon alfa-2b
  • Chickenpox (including recent exposure) or
  • Herpes zoster (shingles) Risk of severe disease affecting other parts of the body
  • Convulsions (seizures) or
  • Mental problems (or history of) Risk of problems affecting the central nervous system may be increased
  • Eye problems May be worsened by interferon alphas; your doctor will want you to have periodic eye exams while you are receiving this medicine.
  • Diabetes mellitus (sugar diabetes) or
  • Heart attack (recent) or
  • Heart disease or
  • Infections or
  • Kidney disease or
  • Lack of blood supply to any part of the body or
  • Liver disease or
  • Lung disease May be worsened by alpha interferons
  • Problems with overactive immune system Alpha interferons make the immune system even more active
  • Thyroid disease Recombinant interferon alfa-2b can cause thyroid problems when it is used to treat hepatitis

Proper Use of This Medicine:

If you are injecting this medicine yourself, use it exactly as directed by your doctor. Do not use more or less of it, and do not use it more often than your doctor ordered. The exact amount of medicine you need has been carefully worked out. Using too much will increase the risk of side effects, while using too little may not improve your condition.

Each package of alpha interferon contains a patient instruction sheet. Read this sheet carefully and make sure you understand:

  • How to prepare the injection.
  • Proper use of disposable syringes.
  • How to give the injection.
  • How long the injection is stable.

If you have any questions about any of this, check with your health care professional.

While you are using alpha interferon, your doctor may want you to drink extra fluids. This will help prevent low blood pressure due to loss of too much water.

Alpha interferons often cause unusual tiredness, which can be severe. This effect is less likely to cause problems if you inject your interferon at bedtime.


The dose medicines in this class will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

Missed dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


Keep out of the reach of children.

Store in the refrigerator. Do not freeze.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions While Using This Medicine:

It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly and to check for unwanted effects.

Do not change to another brand of alpha interferon without checking with your physician. Different kinds of alpha interferon have different doses. If you refill your medicine and it looks different, check with your pharmacist.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that slow down the nervous system, possibly causing drowsiness). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; muscle relaxants; or anesthetics, including some dental anesthetics. Check with your doctor before drinking alcohol or taking any of the above while you are using this medicine.

Alpha interferon may cause some people to become unusually tired or dizzy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or if you are not alert.

This medicine commonly causes a flu-like reaction, with aching muscles, fever and chills, and headache. To prevent problems from your temperature going too high, your doctor may ask you to take acetaminophen (e.g., Tylenol) before each dose of interferon. You may also need to take it after a dose to bring your temperature down. Follow your doctor's instructions carefully about taking your temperature, and how much and when to take the acetaminophen.

Alpha interferon can lower the number of white blood cells in your blood temporarily, increasing the chance of getting an infection. It can also lower the number of platelets, which are necessary for proper blood clotting. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:

  • If you can, avoid being close to people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or have painful or difficult urination.
  • Check with your doctor immediately if you notice any unusual bleeding or bruising; black, tarry stools; blood in urine or stools; or pinpoint red spots on your skin.
  • Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.
  • Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else in the meantime.
  • Be careful not to cut yourself when you are using sharp objects such as a safety razor or fingernail or toenail cutters.
  • Avoid contact sports or other situations where bruising or injury could occur.

If you experience vision problems while receiving an interferon alpha, you should contact your doctor for an eye examination.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Because this medicine is used for many different conditions and in many different doses, the actual frequency of side effects may vary. In general, side effects are less common with low doses than with high doses. Also, when alpha interferon is used for genital warts, very little of it gets into the rest of the body, so side effects are generally less common than in other conditions.

Check with your doctor as soon as possible if any of the following side effects occur:

Less common
mental depression
numbness or tingling of fingers, toes, and face
trouble in sleeping
trouble in thinking or concentrating
Black, tarry stools
blood in urine or stools
chest pain
cough or hoarseness accompanied by fever or chills
fever or chills (beginning after 3 weeks of treatment)
irregular heartbeat
lower back or side pain accompanied by fever or chills
muscle pain
numbness or tingling in the legs
pain, swelling or redness in the joints
painful or difficult urination accompanied by fever or chills
pinpoint red spots on skin
trouble speaking
unusual bleeding or bruising

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
Aching muscles
change in taste or metallic taste
fever and chills (should lessen after the first 1 or 2 weeks of treatment)
general feeling of discomfort or illness
loss of appetite
nausea and vomiting
skin rash
unusual tiredness
Less common or rare
Back pain
blurred vision
dry skin or itching
dryness of mouth
increased sweating
joint pain
leg cramps
sores in mouth and on lips
weight loss

Alpha interferon may cause a temporary loss of some hair. After treatment has ended, normal hair growth should return.

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Last Updated: 6/12/2013
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