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Generic Name

interferon (in ter FEER on)


Trade Name

Intron A


What is interferon?

Interferon is a chemical that occurs naturally in the body in very small amounts. It is one of the body’s defenses against viruses.


What is it used for?

In gastroenterology, interferon is used to treat 2 different chronic virus infections of the liver, chronic hepatitis B and C. The drug has many other uses in other fields of medicine such as hematology.


How do I take it?

Interferon is given by injection only. You or a family member will need to be trained to give this injection. It is not difficult. Sterile technique is required. Your physician will advise you on this. Store this drug in a refrigerator at temperatures of 36 to 46° F. Do not freeze. Keep all medications away from children. Never share your medications with anyone else.


What do I do for a missed dose?

If you miss a dose of this medication, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and return to your regular schedule. Do not double up on this medication.


Are there interactions with food or beverages?

If nausea or vomiting develops, eat dry foods (such as toast or crackers), soups or unsweetened juices in small meals throughout the day. Sugars, sweets, and fried or fatty foods may worsen nausea. Drink 2 to 3 quarts of liquid a day to maintain good urine flow.


Are there interactions with other drugs?

An interaction generally means that one drug may increase or decrease the effect of another drug. Also, the more medications a person takes, the more likely there will be a drug interaction.

Interactions with this drug may occur with the following:

  • aminophylline
  • zidovudine (Retrovir)


Is there a problem if I have another disorder or disease?

At times, a drug may have a different or enhanced effect when other diseases are present. At other times, the drug may worsen or effect another disease.

With this drug, the following disorders may be a problem:

  • depression or suicide attempt
  • mental disorder
  • low white or platelet blood count
  • bone marrow failure
  • thyroid problems
  • heart disease, especially problems of heart rhythm
  • retina hemorrhage or similar eye problems
  • autoimmune diseases
  • blood coagulation disorders


What about allergies?

People who have known allergies or asthma may be at an increased risk for a reaction from any new medication. The physician should always know a patient’s allergy history. Signs of an allergic reaction are skin rash, hives and itching. Of course, a person should not take interferon if there has been a previous reaction to this or a similar drug.


What if I’m pregnant, considering pregnancy or breast-feeding?

Most females now know that, if possible, no drug, including alcohol, should be taken during pregnancy or lactation. The potential danger, of course, is an injury to the baby. However, some drugs are much safer than others in this regard. So, the FDA has a grading system for each drug which reflects what is known medically. It ranks drugs from A, where medical studies show no evidence for danger to the fetus or mother, to B, C, D and X, where the medical evidence indicates that the risk to the fetus outweighs any benefit to the mother. Interferon is ranked C. Always consult your physician before taking any drug during or when planning pregnancy. Use this drug during pregnancy only if the potential effects justify the risk to the fetus. A detailed discussion with your physician is required. Fertile women should not receive interferon unless they are using effective contraception and caution should be used in fertile men.


What are the effects on sexual function?

There are no known adverse effects on sexual function.


Are there other precautions?

  • The major side effect with interferon is the flu-like feeling that can occur for about 24 hours after the injection. This side effect becomes less of a problem the longer the drug is taken. It often can be prevented or reduced by pretreatment with acetaminophen (Tylenol) or aspirin.
  • Depressed and any suicidal thoughts should be reported immediately to your physician.
  • Interferon may cause drowsiness or dizziness. Use caution while driving or performing other tasks requiring alertness.
  • Avoid prolonged exposure to sunlight or sunlamps. Interferon may cause photosensitivity.
  • Patients taking this drug need to be closely monitored by their physician.


How long is it safe to take interferon?

The usual treatment time for hepatitis C is 1 year, for hepatitis B, it is 16 weeks. Physicians are finding that longer use may be needed and seems to be safe. This drug needs to be closely monitored by your physician and the length of therapy depends on individual response to the medication.


How about side effects?

Adverse reactions can occur with any drug, even over-the-counter medications. Some of these are mild such as a stomach upset, which may be avoided by taking the medication with food. Minor reactions may go away on their own but if they persist, contact the physician. For major reactions, the patient should contact the physician immediately.

For interferon, the following are the observed side effects:


  • fever
  • fatigue
  • muscle or joint aches
  • headache
  • chills
  • loss of appetite
  • nausea
  • vomiting
  • abdominal pain
  • dizziness
  • cough
  • loss of hair
  • rash
  • dry mouth
  • itching
  • change in taste


  • suicidal thoughts
  • depression
  • confusion
  • shortness of breath


A physician’s comment…

Interferon is the first drug available to treat chronic hepatitis B and C. In the U.S. it has been found that, while many people respond to the drug, not many are long-term responders, meaning that the virus infection returns when the drug is stopped. That is why new interferons and other anti-viral drugs are being developed. This field is changing rapidly and the future is promising. Keep in contact with your physician.