Infergen treats chronic hepatitis C in adults. It is available as an injection to be administered directly under the skin.

Infergen Overview


Infergen is a prescription medication used to treat lasting (chronic) hepatitis C virus (HCV) infection in adults. Infergen belongs to a group of drugs called synthetic interferons. These work by helping to prevent the hepatitis C virus from growing inside your body. 

This medication is available in an injectable form to be given directly under the skin (subcutaneously), typically three times per week for 24 weeks. Your doctor will decide wheteher you will take Infergen alone or with ribavirin.

Common side effects of Infergen include flu-like symptoms, stomach problems, and hair thinning.

Infergen can also cause drowsiness. Do not drive or operate heavy machinery until you know how Infergen affects you.

Patient Ratings for Infergen

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What are you taking Infergen for?

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  • Other
  • Brain Neoplasms
  • Carcinoma, Hepatocellular
  • Carcinoma, Renal Cell
  • Colorectal Neoplasms
  • Cryoglobulinemia
  • Hemangioma
  • Hepatitis C, Chronic
  • Hepatitis D
  • Hypereosinophilic Syndrome
  • Ileal Neoplasms
  • Leukemia, Hairy Cell
  • Macular Degeneration
  • Melanoma
  • Multiple Myeloma
  • Mycosis Fungoides
  • Sezary Syndrome
  • Skin Neoplasms
  • Skin Ulcer
  • Thrombocythemia, Essential
  • Thrombocytopenia
  • Warts

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  • Less than a week
  • A couple weeks
  • A month or so
  • A few months
  • A year or so
  • Two years or more

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Infergen Cautionary Labels


Uses of Infergen

Infergen is a prescription medication used to treat lasting (chronic) hepatitis C virus (HCV) infection in adults with certain levels of hepatitic C antibodies in their blood.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.


Interferon Alfacon-1

For more information on this medication choose from the list of selections below.

Infergen Drug Class

Infergen is part of the drug class:

Side Effects of Infergen

Serious side effects have been reported with Infergen. See the “Infergen Precautions” section.

Common side effects of Infergen include the following:

  • fatigue
  • fever
  • body pain
  • flu-like symptoms
  • injection-site redness
  • headache
  • insomina
  • dizziness
  • muscle pain
  • nausea
  • diarrhea
  • hair thinning

This is not a complete list of Infergen side effects. Ask your doctor or pharmacist for more information.

Tell your doctor if you have any side effect that bothers you or that does not go away.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Infergen Interactions

Tell your doctor about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:
  • abacavir
  • aldesleukin
  • bexarotene
  • bupropion
  • clozapine
  • deferiprone
  • eltrombopag
  • fingolimod
  • iohexol
  • iopamidol
  • lamivudine
  • leflunomide
  • lomitapide
  • metrizamide
  • mipomersen
  • natalizumab
  • samarium
  • telbivudine
  • teriflunomide
  • tofacitinib
  • tramadol
  • zidovudine

This is not a complete list of Infergen drug interactions. Ask your doctor or pharmacist for more information.

Infergen Precautions

Serious side effects have been reported with Infergen including the following:

  • flu-like symptoms. Infergen causes “flu-like” symptoms in most patients. Symptoms include headache, muscle aches, tiredness, chills and fever that usually lessen after the first few weeks of therapy. If you inject your Infergen dose at bedtime, you may be able to sleep through the symptoms. You may also take a fever and pain reducer such as acetaminophen or ibuprofen, to help relieve or reduce the flu-like symptoms.
  • blood sugar problems. Infergen may affect blood sugar levels and cause high blood sugar or diabetes. Talk to your physician about before taking Infergen if you have diabetes.
  • skin reactions at the injection-site. Redness, rash, itching, swelling, or bruising that does not go away may occur at the site of injection. Call your healthcare provider if these symptoms do not go away after several days.
  • neuropsychiatric disorders. Severe psychiatric problems may occur in patients receiving therapy with medications like Infergen including depression, suicidal ideation, suicide attempts, psychosis, aggressive behavior, nervousness, anxiety, emotional lability, abnormal thinking, agitation, apathy and/or relapse of drug addiction. Infergen should be used with extreme caution in patients who report a history of depression. Immediately report any sign or symptom of depression and/or suicidal ideation to your physician.
  • bone marrow toxicity. Your physician will monitor your blood levels while you are taking Infergen and adjust your dose if necessary.
  • cardiovascular disorders. High blood pressure, abnormally fast heart rate, and palpitations have been reported in patients treated with Infergen. Infergen should be administered with caution to patients with preexisting cardiac disease.
  • acute hypersensitivity reactions. Serious acute hypersensitivity reactions have been reported in rare instances following treatment with medications similar to Infergen. Infergen should be discontinued immediately and appropriate medical treatment instituted if you experience the following symptoms
    • swelling of the lips or mouth
    • difficulty breathing
    • hives
  • endocrine disorders. Occurrence or aggravation of hyperthyroidism or hypothyroidism have been reported with Infergen. High blood sugar and diabetes have also been observed in patients treated with Infergen. Patients who develop these conditions during treatment that cannot be controlled with medication should not continue Inferger therapy. Talk to your physician about before taking Infergen if you have any endocrine conditions.
  • autoimmune disorders. Development of or exacerbation of autoimmune disorders have been reported in patients receiving Infergen. Infergen should not be used in patients with autoimmune hepatitis and should be used with caution in patients with other autoimmune disorders.
  • lung disorders. Pneumonia and interstitial pneumonitis, some cases esulting in respiratory failure and/or patient deaths, have been induced or aggravated by Infergen. Talk to your physician about before taking Infergen if you have any lung conditions.
  • colitis. Hemorrhagic/ischemic colitis, sometimes fatal, has been observed in patients treated with Infergen. Talk to your physician about before taking Infergen if you have any intestinal conditions.
  • eye disorders. Decrease or loss of vision, retinopathy including macular edema, retinal artery or vein thrombosis, retinal hemorrhages and cotton wool spots; optic neuritis, and papilledema may be induced or aggravated by treatment with Infergen. All patients should receive an eye examination at baseline. Patients with preexisting ophthalmologic disorders should receive periodic ophthalmologic exams during interferon alpha treatment. Any patient who develops ocular symptoms should receive a prompt and complete eye examination. Infergen therapy should be discontinued in patients who develop new or worsening ophthalmologic disorders.
  • cerebrovascular disorders. Strokes have been observed in patients treated with Infergen. Events occurred in patients with few or no reported risk factors for stroke, including patients less than 45 years of age. Talk to your physician about before taking Infergen if you have any history of strokes or heart disease.

Do not take Infergen if you:

  • are allergic to Infergen or to any of its ingredients
  • have decompensated hepatic disease
  • have autoimmune hepatitis

Infergen can also cause drowsiness, dizziness, and/or blurred vision. Do not drive or operate heavy machinery until you know how Infergen affects you.

Infergen Food Interactions

Medications can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of Infergen, there are no specific foods that you must exclude from your diet when receiving this medication.

Inform MD

Before taking Infergen, tell your doctor about all of your medical conditions. Especially tell your doctor if you:

  • are allergic to Infergen or to any of its ingredients
  • have diabetes
  • have autoimmune diseases
  • have depression
  • have heart disease
  • have hyperthyroidism
  • have hypothyroidism
  • have idiopathic pulmonary fibrosis
  • have cystic fibrosis
  • have Crohn's disease
  • have any eye conditions
  • are pregnant or plan to become pregnant
  • are breastfeeding or plan to breastfeed

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

Infergen and Pregnancy

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

Infergen falls into category C. In animal studies, pregnant animals were given this medication and had some babies born with problems. No well-controlled studies have been done in humans. Therefore, this medication may be used if the potential benefits to the mother outweigh the potential risks to the unborn child.

Infergen and Lactation

Tell your doctor if you are breastfeeding or plan to breastfeed.

It is not known if Infergen crosses into human milk. Because many medications can cross into human milk and because of the possibility for serious adverse reactions in nursing infants with use of this medication, a choice should be made whether to stop nursing or stop the use of this medication. Your doctor and you will decide if the benefits outweigh the risk of using Infergen.

Infergen Usage

Take Infergen exactly as prescribed.

  • This medication is available in an injectable form to be given directly under the skin (subcutaneously), typically three times per week for 24 weeks. At least 48 hours should elapse between doses of Infergen
  • Do not reduce the dosage of Infergen prior to medical consultation
  • If self-injection is determined to be appropriate by your physician, instructions on appropriate use will be given to you by a healthcare professional

Administer Infergen exactly as instructed by your physician. You may refer to the following instructions for aditional information:

Initial Preparation

Assemble the supplies you will need for your injection:

  • A vial of Infergen
  • One sterile disposable syringe and needle
  • Several alcohol swabs
  • A puncture-proof container to dispose of the needle and syringe when you are done

Make sure you have the right syringe to use with Infergen. It is important to use a syringe that is marked in tenths of millimeters (mLs), for example, 0.1 mL. Your healthcare provider may refer to a mL as a cc (1 mL = 1 cc). Failure to use the right syringe can lead to a mistake in dosage. You may receive too little or too much Infergen.

Check the date on the vial of Infergen and make sure that the date has not passed and look at the liquid inside the vial.

Do not use Infergen if:

  • The liquid is cloudy
  • The liquid is not clear and colorless
  • The liquid has particles
  • The expiration date has passed

Selecting The Injection Site

Find a clean, comfortable, well-lit place and remove a vial of Infergen from the refrigerator and allow it to reach room temperature.

Wash your hands thoroughly with soap and water.

Pick a site for your injection:

  • Back of the upper arms (if someone is giving you the injection)
  • Upper stomach area (abdomen), except for the belly button (navel) and waist areas
  • Upper thighs

You should change the site for injection each time you inject to avoid soreness at any one site.

Clean the injection site with an alcohol swab. Use circular motions from the inside to the outside. Keep the used alcohol swab nearby.

Preparing the Dose

  1. Remove the colored cap from the vial, exposing the rubber stopper.
  2. Clean the rubber stopper with a new alcohol swab, and then cover the stopper with the swab
  3. Remove the syringe and needle from their packages. If either package looks like there have been opened or damaged, do not use the syringe or needle; dispose of it in the puncture-proof disposal container.
  4. Remove the needle cover and pull the plunger back and draw air into the syringe. The amount of air you draw into the syringe should be the same amount as the dose of medicine your healthcare provider has prescribed.
  5. Remove the alcohol wipe from the top of the vial and insert the needle straight through the center of the rubber stopper.
  6. Push the plunger of the syringe down to inject the air into the air space above the liquid in the vial. The air injected into the vial will allow Infergen to be easily withdrawn from the vial into the syringe.
  7. Keeping the needle in the vial, turn the vial upside down and make sure that the tip of the needle is in the liquid.
  8. Slowly pull the plunger back and let the medicine enter the syringe, filling it to the line that equals the dose your healthcare provider prescribed.
  9. Keeping the needle in the vial, check for air bubbles in the syringe. Air bubbles are harmless but can reduce the dose you should be receiving. To remove the air bubbles, gently tap the syringe with your fingers until the bubbles rise to the needle-end of the syringe barrel. Then push the plunger in to force the air out of the syringe.
  10. Make sure the tip of the needle is in the liquid and slowly pull back on the plunger until the liquid in the syringe reaches the mark that correctly matches the amount of your dose.
  11. Take the needle out of the vial and hold the syringe needle facing up in the hand that you will use to inject yourself. Do not lay the syringe down or allow the needle to touch anything.

Injecting The Dose

  1. After the needle is in, let go of the skin. Pull the plunger back slightly. If blood appears, do not inject Infergen, because the needle has entered a blood vessel. Withdraw the syringe and discard it. Prepare a new syringe and inject at a new site. Repeat this procedure at the second site, checking for blood before injecting.
  2. Hold the syringe the way you would hold a pencil and insert the needle either straight up and down (90 degree angle) or at a slight angle (45 degree angle) to the skin.
  3. Use the other hand to pinch a fold of skin at the site you cleaned for an injection.
  4. If no blood appears, slowly push down on the plunger all the way, until all the medicine is gone from the syringe.
  5. Pull the needle out of the skin at the same angle you put it in and place an alcohol swab over the injection site, then press for several seconds.
  6. Promptly place the needle and syringe in the puncture-proof disposal container. Never reuse the syringe or needle. Do not recap the needle.


  • Dispose of syringes and needles as directed by your healthcare provider or pharmacist. There may be special state and local laws.
  • Place all used needles, needle covers, and syringes in a special container called a “Sharps Container” or a hard plastic container‚ or a metal container with a plastic lid. Do not use glass or clear plastic containers‚ or any container that will allow the needles to stick through them.
  • Always keep the container out of the reach of children.
  • Do not recycle containers or throw full containers into the household trash.

If you miss a dose, take the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed dose and take your next dose at the regular time. Do not take two doses of Infergen at the same time.

Infergen Dosage

Take this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The dose your doctor recommends may be based on the following:

  • the condition being treated
  • other medical conditions you have
  • other medications you are taking
  • how you respond to this medication
  • your weight
  • your age

The recommended dose of Infergen for the treatment of lasting (chronic) hepatitis C virus (HCV) infection in adults is 9 mcg injected subcutaneously as a single injection three times per week for 24 weeks.

Infergen Overdose

If you take too much Infergen, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

Other Requirements

  • Store Infergen in the refrigerator at 36° to 46°F (2° to 8°C)‚ but not in the freezer compartment.
  • Just prior to injection, Infergen may be allowed to reach room temperature.
  • Do not let Infergen freeze or leave it in direct sunlight.
  • Do not use a vial of Infergen that has been frozen or past the expiration date stamped on the label. If you think that the Infergen has been frozen or left in direct sunlight‚ do not use it‚ and call your healthcare provider or nurse for instructions.
  • To transport Infergen‚ keep the vials cool and avoid extreme temperature changes.
  • Do not shake Infergen. If Infergen is shaken too hard, it will not work properly.
  • Keep Infergen and all medicines out of the reach of children.