What is Infergen?

Commonly Used Brand Name(s)Infergen

Therapeutic ClassificationsImmunological Agent

Pharmacologic ClassificationsInterferon, Alfa (class)



Blackbox WarningTOP

Subcutaneous route (Solution)

May cause or aggravate fatal or life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders. Monitor closely and withdraw therapy with persistently severe or worsening signs or symptoms of the above disorders. Use with ribavirin: Ribavirin may cause birth defects and fetal death; avoid pregnancy in female patients and in female partners of male patients. Ribavirin causes hemolytic anemia, which may exacerbate cardiac disease .


Interferon alfacon-1 is used to treat chronic hepatitis C in adults. Hepatitis C is a liver infection. Interferons are natural substances that are produced in the body to help fight infections. Interferon alfacon-1 is a synthetic (man-made) version of these substances. This medicine will not keep you from giving hepatitis C to other people.

This medicine is available only with your doctor's prescription.

Proper UseTOP

A nurse or other trained health professional will give you this medicine. This medicine is given as a shot under your skin.

You may also be taught how to give this medicine at home. Make sure you understand all of the instructions before giving yourself an injection. Do not use more medicine or use it more often than your doctor tells you to.

Each package of interferon alfacon-1 contains a medication guide. Carefully read the guide and make sure you understand:

  • How to prepare the injection.
  • How to properly use a disposable syringe.
  • How to give yourself the injection.
  • How to store the vial of medicine.
  • How long the vial can be stored and used.

You will be shown the body areas where this shot can be given. Use a different body area each time you give yourself a shot. Keep track of where you give each shot to make sure you rotate body areas.

Use a new needle and syringe each time you inject your medicine.

To help clear up your infection completely, interferon alfacon-1 must be used for the full time of treatment, even if you begin to feel better after a few days or weeks. It is also very important that you receive your injection at the same time of day for each dose.

Use each vial (glass container) only one time. If the vial contains extra medicine, throw it away.

If you have any questions about any of this, check with your doctor.

Do not change to another brand of interferon without checking with your doctor first. Different types of interferon require different doses. If you refill your medicine and it looks different, check with your pharmacist.

If you have any questions about this information, check with your doctor.


The dose of this medicine 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 this medicine. 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.

  • For injection dosage form:
    • For hepatitis C:
      • For patients receiving interferon alfacon-1 only:
        • Adults—9 micrograms (mcg) injected under the skin three times per week. The injections should be spaced at least 48 hours apart.
        • Children—Use is not recommended.
      • For patients receiving interferon alfacon-1 together with ribavirin:
        • Adults—15 micrograms (mcg) injected under the skin once a day. It is taken together with 1000 to 1200 milligrams (mg) of ribavirin divided in two small doses per day.
        • Children—Use is not recommended.

Missed DoseTOP

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.

After you take the missed dose, call your doctor for instructions.

Use & StorageTOP

Store in the refrigerator. Do not freeze.

Keep out of the reach of children.

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.

Allow this medicine to reach room temperature before using it. Do not shake the vial or expose it to direct sunlight.

Throw the used needles away in a hard, closed container that the needles cannot poke through. Keep this container away from children and pets.

Before UsingTOP

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine 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.


Appropriate studies have not been performed on the relationship of age to the effects of interferon alfacon-1 in the pediatric population. Safety and efficacy have not been established.


Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of interferon alfacon-1 in the elderly. However, elderly patients are more likely to have age-related kidney, liver, or heart problems, which may require caution and an adjustment in the dose for patients receiving interferon alfacon-1.


Pregnancy CategoryExplanation
All TrimestersCAnimal studies have shown an adverse effect and there are no adequate studies in pregnant women OR no animal studies have been conducted and there are no adequate studies in pregnant women.

Breast FeedingTOP

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug InteractionsTOP

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

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

Other InteractionsTOP

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 ProblemsTOP

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

  • Autoimmune hepatitis (liver inflammation) or
  • Decompensated liver disease or
  • Kidney disease, severe or
  • Sickle cell anemia (red blood cell disorder) or
  • Thalassemia major (genetic blood disorder)—Should not be used in patients with these conditions.
  • Infection—May decrease your body's ability to fight infection.


It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Using this medicine together with ribavirin while you are pregnant can harm your unborn baby. The medicine may also cause birth defects if the father is using it when his sexual partner becomes pregnant. If a pregnancy occurs while you are using this medicine, tell your doctor right away.

A negative pregnancy test is needed in women who are of childbearing age before starting combination treatment with interferon alfacon-1 and ribavirin. Two forms of birth control must be used during treatment and for six months after treatment ends. You will need to have pregnancy tests done regularly to make sure you are not pregnant while being treated with these medicines and after your treatment ends.

This medicine commonly causes a flu-like reaction, with aching muscles, fever, chills, and headache. Using your shot at bedtime may allow you to sleep through the symptoms. Your doctor may want you to take a medicine for pain and fever (such as acetaminophen or ibuprofen) before or after each dose of interferon alfacon-1. Carefully follow your doctor's instructions about how to prevent or treat these symptoms.

This medicine may cause some people to be agitated, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. If you or your caregiver notice any of these side effects, tell your doctor right away.

This medicine may lower the number of white blood cells in the blood. This will increase your chance of getting an infection. It can also lower the number of platelets in the blood. Platelets 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 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 painful or difficult urination.
  • Check with your doctor immediately if you notice any unusual bleeding or bruising; black, tarry stools; blood in the 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.

This medicine may cause serious allergic reactions including anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Call your doctor right away if you have a rash; itching; hoarseness; trouble breathing; trouble swallowing; or any swelling of your hands, face, or mouth while you are using this medicine.

Stop using this medicine and check with your doctor right away if you have fever, stomach cramps, tenderness, pain, or watery or bloody diarrhea. These may be symptoms of a serious stomach problem called colitis.

Pancreatitis may occur while you are using this medicine. Tell your doctor right away if you have sudden and severe stomach pain, chills, constipation, nausea, vomiting, fever, or lightheadedness.

Check with your doctor immediately if blurred vision, difficulty in reading, or any other change in vision occurs during or after treatment. Your doctor may want you to have your eyes checked by an ophthalmologist (eye doctor).

Check with your doctor right away if you are having burning, numbness, tingling, or painful sensations in the arms, hands, legs, or feet. These could be symptoms of a condition called peripheral neuropathy.

Check with your doctor right away if you are having trouble breathing or if you experience a respiratory infection (such as pneumonia). This could result in a serious respiratory condition.

This medicine may cause high blood sugar levels. If you are diabetic and notice a change in the results of your blood or urine sugar tests, check with your doctor.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

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