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Trade/other name(s): Neulasta, pegylated granulocyte-colony stimulating factor (G-CSF)

Why would this drug be used?

Pegfilgrastim is used to prevent or treat neutropenia (having a lower than normal number of white blood cells called neutrophils), which in turn lowers a person's risk of serious infections. Neutropenia can sometimes occur as a result of cancer chemotherapy or other treatments.

How does this drug work?

Pegfilgrastim is a longer-acting form of the drug filgrastim.

Filgrastim is a man-made version of a protein called granulocyte-colony stimulating factor (G-CSF). This protein is normally made by some cells in the body to stimulate the bone marrow to make more infection-fighting white blood cells called neutrophils. The man-made version (filgrastim) has the same effect when injected into the body.

Pegfilgrastim is made by attaching filgrastim to a molecule called polyethylene glycol (PEG). This addition helps it stay in the body longer than filgrastim, which means it can be given less often and still get the same result.

Before taking this medicine

Tell your doctor…

  • If you are allergic to any medicines, dyes, additives, or foods, especially if you have problems with any drug made with E. coli.
  • If you have sickle cell disease. This drug may raise your risk of having a serious sickle cell crisis.
  • If you have any other medical conditions such as kidney disease, liver disease (including hepatitis), heart disease, lung disease, congestive heart failure, diabetes, gout, or infections. You may need closer monitoring of these conditions while being treated.
  • If you have ever had an enlarged spleen, myelodysplastic disease, or chronic myeloid leukemia. This drug may worsen these conditions or cause other problems.
  • If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. It is not known if this drug might cause problems if either the male or female is taking it at the time of conception or during pregnancy. Check with your doctor about what kinds of birth control can be used with this medicine. This drug should be used during pregnancy only if the expected benefit is thought to outweigh the potential risk to the fetus.
  • If you are breast-feeding. While no studies have been done, this drug may pass into breast milk and affect the baby. Talk with your doctor about the possible risks of breast-feeding while taking this drug.
  • About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

Pegfilgrastim should be used with caution in people taking lithium, as it may cause more neutrophils than normal to enter the bloodstream.

No serious interactions with other drugs are known at this time. But this does not necessarily mean that none exist. Check with your doctor, nurse, or pharmacist about all of your medicines, herbs, and supplements, and whether alcohol can cause problems with this medicine.

Interactions with foods

No serious interactions with food are known at this time. Check with your doctor, nurse, or pharmacist about whether some foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Pegfilgrastim is given as a shot under the skin (subcutaneously, or SubQ). The dose is 6 milligrams (mg), given once each chemotherapy cycle. It can be given in a doctor's office, or you or a family member can learn how to give the shot under the skin at home.

If you are taking it at home, make sure to keep the medicine in its original container in the refrigerator. Take this drug exactly as directed by your doctor. If you are not sure of the instructions, ask your doctor or nurse to explain them to you. Keep the needles and other equipment in a safe place out of reach of children and pets. Keep used needles in a closed needle bucket and bring them back to your doctor or nurse.


Patients with acute myeloid leukemia (AML) or chronic myelogenous leukemia (CML) should not get this drug, as it could potentially spur the growth of these types of cancer cells.

This drug should not be given within 14 days before or 24 hours after chemotherapy treatments.

Your doctor will obtain blood tests to find out how you respond to the drug. Your doctor will adjust your dose based on your test results. Keep all your appointments for doctor visits and blood tests.

Even though this drug is given to help you fight infections, it cannot prevent all infections. Call your doctor if you notice signs of infection such as fever (100.5° or higher), chills, pain when passing urine, a new cough, or bringing up sputum.

In rare cases, this drug can cause allergic reactions when the drug is given, especially with the first few treatments. Mild reactions may consist of fever, chills, skin itching, or feeling flushed. More serious reactions happen rarely, but can be dangerous. Symptoms can include feeling lightheaded or dizzy (due to low blood pressure), chest tightness, shortness of breath, back pain, or swelling of the face, eyes, tongue, or throat. Tell your doctor or nurse right away if you notice any of these symptoms during or after being given the drug. After treatment for such a reaction, symptoms may come back a few days later and require that you be treated again.

In rare cases, people getting this drug have had their spleen grow very large or even rupture, which can cause death. Let your doctor know right away if you begin to have pain or swelling on your left side under your rib cage or if you notice pain in your left shoulder area.

In rare cases, people with very low white blood cells counts and severe blood infections (sepsis) who were given pegfilgrastim developed a potentially life-threatening lung condition known as acute respiratory distress syndrome (ARDS). Tell your doctor or nurse right away if you begin to notice shortness of breath, cough, or fever.

If you are having surgery, including dental surgery, tell your surgeon or dentist that you are using Pegfilgrastim.

If you plan to have a bone imaging study, be sure the doctor and technician know you are using this drug. Pegfilgrastim may affect the imaging results.

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.

Less common

  • bone or muscle pain
  • injection site reaction (redness, pain, or swelling)


  • allergic reaction*
  • spleen enlargement or rupture*
  • serious lung problems (ARDS) *
  • coughing up blood

*See the "Precautions" section for more detailed information.

There are other side effects not listed above can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved in 2002.

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.

Last Medical Review: 11/19/2009
Last Revised: 07/01/2011