Care During Chemotherapy and Beyond

Interferon Alfa-2b (PEG Conjugate)

Generic Name: PEG Interferon
Trade Name: PEG-INTRON

Drug type: PEG Interferon alfa-2b is a "biologic response modifier."  This medication is classified as a "cytokine." (For more detail, see "How this drug works" section below).

What This Drug Is Used For:

  • This medication is used to treat chronic hepatitis C.
  • This medication is also being investigated for use in various cancers.

Note:  If a drug has been approved for one use, physicians sometimes elect to use this same drug for other problems if they believe it might be helpful.

How This Drug Is Given:

  • This medication is given by injection under the skin (subcutaneous, SubQ). 
  • It is given as a once a week injection.
  • You may be taught to give yourself the injection if you are willing and able to learn.
  • The amount of this medication you will receive depends on many factors, including your height and weight, your general health or other health problems, and the type of cancer you have.  Your doctor will determine your dosage and schedule.

Side Effects:

Important things to remember about the side effects of PEG Interferon alfa-2b:

  • You will not get all of the side effects mentioned below.
  • Side effects are often predictable in terms of their onset and duration.
  • Side effects are almost always reversible and will go away after therapy is complete.
  • Side effects are quite manageable, and there are many options to minimize or prevent them.
  • There is no relationship between the presence or severity of side effects and the effectiveness of the medication.

The following side effects are common (occurring in greater than 30%) for patients taking PEG Interferon alfa-2b:

  • Flu-like symptoms (headache, muscle aches, tiredness and fever) usually lessen after the first few weeks of treatment. 
  • Fatigue 
  • Injection site reactions (bruising, itching, irritation).
  • Poor appetite 
  • Nausea

The following are less common side effects (occurring in 10-29%) for patients receiving PEG Interferon alfa-2b:

  • Depression 
  • Anxiety/ irritability 
  • Insomnia (see sleep problems)
  • Joint and bone pain (see pain)
  • Temporary hair thinning. Your hair will grow back after you stop taking this medication. 
  • Diarrhea 
  • Abdominal pain 
  • Itching 
  • Dizziness 
  • Weight loss 
  • Dry skin
  • Trouble concentrating (see central neurotoxicity).

This list includes common and less common side effects for individuals taking PEG Interferon alfa-2b.   Side effects that are very rare, occurring in less than 10% of patients, are not listed here.  However, you should always inform your health care provider if you experience any unusual symptoms.

When to contact your doctor or health care provider:

Contact your health care provider immediately, day or night, if you should experience any of the following symptoms:

  • Shortness of breath, chest pain, rapid heart beat
  • Depressed or have any thoughts of hurting yourself or others

The following symptoms require medical attention, but are not emergency situations.  Contact your health care provider within 24 hours of noticing any of the following:

  • Unusual bleeding or bruising
  • Black or tarry stools, or blood in your stools or urine
  • Diarrhea (4-6 episodes in a 24-hour period)
  • Nausea that interferes with eating and is not relieved by prescribed medications
  • Vomiting (vomiting more than 4-5 times in a 24-hour period)
  • Persistent abdominal pain
  • Feeling "faint" or dizzy
  • Unusual fatigue
  • Anxiety, changes in thinking or mood, confusion, difficulty concentrating or trouble sleeping
  • Changes in eyesight

Always inform your health care provider if you experience any unusual symptoms.


  • Before starting PEG Interferon alfa-2b treatment, make sure you tell your doctor about any other medications you are taking (including over-the-counter, vitamins, or herbal remedies).  Do not take aspirin or products containing aspirin unless your doctor permits this.
  • PEG Interferon alfa-2b may cause patients to develop mood or behavioral problems.  Make sure to tell your doctor if you are being treated for a mental illness or had treatment in the past for any mental illness, including depression and suicidal behavior. You should also tell your doctor if you have ever been addicted to drugs or alcohol.
  • Inform your health care professional if you are pregnant or may be pregnant prior to starting this treatment.  Pregnancy category C (use in pregnancy only when benefit to the mother outweighs risk to the fetus). 
  • For both men and women: Do not conceive a child (get pregnant) while taking PEG Interferon alfa-2b.  Barrier methods of contraception, such as condoms, are recommended. Discuss with your doctor when you may safely become pregnant or conceive a child after therapy.
  • Do not breast feed while taking this medication.

Self-Care Tips:

  • Take injections at bedtime.  You may be able to sleep through "flu-like" symptoms. 
  • Drink 2 to 3 quarts of fluid every 24 hours, unless you were told to restrict your fluid intake.
  • For flu-like symptoms, keep warm with blankets and drink plenty of liquids.  There are medications that can help reduce the discomfort caused by chills.
  • Acetaminophen or ibuprofen may help relieve discomfort from fever, headache, generalized aches and pains.  However, be sure to talk with your doctor before taking it.
  • You may be at risk of infection so try to avoid crowds or people with colds or not feeling well, and report fever or any other signs of infection immediately to your healthcare provider. 
  • Wash your hands often.
  • Avoid sun exposure.  Wear SPF 15 (or higher) sun block and protective clothing.
  • To reduce nausea, take anti-nausea medications as prescribed by your doctor, and eat small, frequent meals.
  • In general, drinking alcoholic beverages should be kept to a minimum or avoided completely.  You should discuss this with your doctor.
  • You may experience drowsiness or dizziness; avoid driving or engaging in tasks that require alertness until your response to this drug is known.
  • Conserve energy, try to get plenty of rest.
  • Patients receiving this medication should have regular eye exams, especially if you have a history of diabetes or high blood pressure. Report any changes in vision immediately. 
  • If you experience symptoms or side effects, be sure to discuss them with your health care team.  They can prescribe medications and/or offer other suggestions that are effective in managing such problems.

Monitoring and Testing:

  • You will be checked regularly by your health care professional while you are taking PEG Interferon alfa-2b, to monitor side effects and check your response to therapy.  Periodic blood work to monitor your complete blood count (CBC) as well as the function of other organs (such as your kidneys and liver) will also be ordered by your doctor.    
  • Your thyroid gland may also be affected by this medication. Your healthcare provider may order a blood test periodically to assess your thyroid function.

How This Drug Works:

PEG Interferon alfa-2b is interferon alfa-2b with a substance called polyethylene glycol (PEG) attached to it.  The attachment process is called pegylation, and is used to allow active substances (the interferon alfa-2b) to stay in the body longer before they are broken down and eliminated.

Interferon alfa-2b belongs to the category of therapies called biologic response modifiers (BRM), also called immunotherapy.  This is a type of treatment that mobilizes the body's immune system to fight cancer.   The therapy mainly consists of stimulating the immune system to help it do its job more effectively.

Interferon alfa-2b is part of a family of proteins called cytokines.  Cytokines act primarily by communicating between the various cells of the body's immune system.

Interferon alfa-2b interacts with receptors on the surface of cells.  There are several ways that interferon alfa-2b fights cancer; directly by interfering with the cancer cells ability to divide, and indirectly by modifying the body's response to the cancer cells. 

Note:  We strongly encourage you to talk with your health care professional about your specific medical condition and treatments. The information contained in this website is meant to be helpful and educational, but is not a substitute for medical advice. is designed to provide the latest information about chemotherapy to patients and their families, caregivers and friends. For information about the 4th Angel Mentoring Program visit