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

Why would this drug be used?

Filgrastim is used to prevent or treat neutropenia, a condition in which the number of white blood cells is very low. Neutropenia can result from cancer chemotherapy or other conditions. Patients with neutropenia are more prone to serious infections. Filgrastim promotes white blood cell growth, which helps the immune system fight infections.

Filgrastim is also sometimes used to stimulate the bone marrow to make more young white blood cells (stem cells) and release them into the bloodstream, where they can be collected for a peripheral blood stem cell transplant (PBSCT).

How does this drug work?

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. Filgrastim has the same effect when injected into the body.

Before taking this medicine

Tell your doctor…

  • If you are allergic to any medicines, dyes, additives, or foods, especially if you are allergic medicines made from E. coli bacteria. Also, if you or the person who will help you inject the filgrastim is allergic to natural rubber (latex).
  • If you have sickle cell disease. This drug may raise your risk of having a serious sickle cell crisis.
  • If you have ever had seizures. This drug may raise your risk of seizures.
  • 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. This drug may make some of these conditions worse. You may need closer monitoring of these conditions while being treated, or the drug dose, regimen, or timing may need to be changed.
  • If you have ever had an enlarged spleen, myelodysplastic syndrome, 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 take this drug during pregnancy, check with your doctor about being in a special registry to observe for any possible effects in the baby (see the 800 number below).
  • If you are breastfeeding. This drug may pass into breast milk, but would not be expected to harm the baby. Talk with your doctor about the possible risks of breastfeeding while taking this drug. If you do breast-feed while taking the drug, you or your doctor can enroll the baby in a special registry by calling 1-800-772-6436 to help monitor children for possible effects.
  • 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

Filgrastim 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?

Filgrastim is usually given as a shot under the skin (subcutaneously, or SubQ). It may also be given as part of an intravenous (IV) infusion over 15 to 30 minutes. It is usually injected once a day, at the same time each day for up to 2 weeks or until a patient's neutrophil blood count reaches a certain level. 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.

The dose and treatment schedule will depend on your weight, general health, and the reason you are being treated. The dose and/or schedule may need to be changed based on how your body responds to treatment.

If you are taking filgrastim at home, make sure to keep it in its original container in the refrigerator. Remove it from the refrigerator about half an hour before you plan to take it so that it can warm up to room temperature. Do not shake the vial or syringe that contains the drug. See the patient information leaflet for more details.

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. Store used needles in a closed needle bucket and bring them back to your doctor or nurse for disposal.


This drug should be used with caution, if at all, in patients with chronic myelogenous leukemia (CML) or myelodysplastic syndrome, as it could potentially spur the growth of cancer cells.

This drug is generally not given within 24 hours of chemotherapy treatments or during radiation therapy.

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 a few people, this drug has caused severe lung problems including acute respiratory distress syndrome and alveolar hemorrhage (bleeding in the small blood vessels of the lungs). Let your doctor know right away of any shortness of breath or coughing up blood that you notice, especially if you also have fever.

In rare cases, this drug can cause allergic reactions, especially with the first few treatments. Mild reactions may consist of fever, chills, skin rash, 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), fast heartbeat, chest tightness, shortness of breath, wheezing, 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.

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.

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

If you plan to have a bone imaging test, be sure the doctor and technician know you are using this drug. Filgrastim may affect the imaging results. The drug has also been known to cause osteoporosis in children.

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.


  • None

Less common

  • Bone and muscle pain
  • Abnormal blood tests which suggest that the drug is affecting the liver (Your doctor will discuss the importance of this finding, if any.)


  • Injection site reaction (redness, pain, itching, or swelling)
  • Allergic reaction*
  • Spleen enlargement or rupture*
  • Low platelet count with high risk of bleeding
  • Vasculitis (inflamed blood vessels) in the skin, causing pain, itching, unexplained bruising, or lumps.
  • Trouble breathing, fever, or coughing up blood (acute respiratory distress syndrome or alveolar hemorrhage)*
  • Death due to spleen rupture, bleeding, sickle cell crisis (in people with sickle cell anemia)

*See “Precautions” section for more detailed information.

There are some other side effects not listed above that 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 1991.

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: 11/08/2013
Last Revised: 12/03/2013