Using Neupogen to Treat Low Neutrophil Count During Chemotherapy

A syringe and two vials of chemotherapy drugs
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Your oncologist may have recommended Neupogen injections if you are having chemotherapy for breast cancer. What is the purpose of these injections, how are they done, and what side effects might you experience?


Neupogen (filgrastim) is a drug given to people receiving chemotherapy who have a low neutrophil count (chemotherapy-induced neutropenia.) Neutrophils are a type of white blood cell which helps prevent infection.

Neupogen works by stimulating the bone marrow to increase the production of white blood cells.It is a clear liquid that is usually given as a shot (injection.)

Neupogen may be given preventively after chemotherapy which will likely severely reduce your neutrophil count (such as double dose Cytoxan and Adriamycin.) At other times it may be given if your blood tests show that your white blood cell count, specifically your absolute neutrophil count, is low enough to put you at serious risk of developing an infection.

Neupogen in People With Breast Cancer

Chemotherapy for breast cancer affects all the rapidly dividing cells in your body, including the cells in the bone marrow which make white blood cells, red blood cells, and platelets. When all of these blood cells are reduced, it is referred to as bone marrow suppression from chemotherapy.

While people may develop a low level of red blood cells (chemotherapy-induced anemia) and platelets (chemotherapy-induced thrombocytopenia) it is usually a low level of neutrophils (chemotherapy-induced neutropenia) which poses the most risk.

During chemotherapy, your oncologist will check your CBC often.

How Neupogen Works

Usually, your body produces a protein that stimulates the production of neutrophils in the process called hematopoiesis. But during chemo for breast cancer, your body may not make enough of this protein. Your CBC may reveal that your neutrophil blood counts are low and that you are neutropenic.

Neupogen injections will boost production of your neutrophils. You may feel aches and some bone pain while this drug is working, but it may help to imagine your immune system rebuilding itself and becoming stronger at protecting your health.


You will have injections of Neupogen once daily until your white blood cell counts return to normal levels. When properly given, these injections will not hurt. This drug can also be given through an intravenous infusion (IV).

Side Effects

Not everyone will have side effects on Neupogen, but both bone pain and a fever are quite common. The pain will usually feel like a deep ache in the regions of your body where most of your blood cells are made, such as your breastbone, your upper legs, and your pelvis.

Usually, treatment is not needed for bone pain but talk to your doctor ahead of time. She may recommend that you take Tylenol (acetaminophen ) or Advil (ibuprofen) but, since medications can interact or pose problems if your liver or kidneys are not working properly, it is important to clear this ahead of time. Many people find that soaking in a warm bath helps alleviate much of the bone pain.

When Should You Call Your Doctor

Reactions may sometimes occur and you should call your doctor right away if you should develop:

  • An allergic reaction (hives; problems breathing; swelling of the face, lips, tongue or throat; rash spreading over your body)
  • Abdominal pain
  • Shoulder pain

You should also call your doctor if you note any chest pain, heart palpitations, or unusual fatigue or lethargy.


Neupogen is a very safe drug used for many types of neutropenia. There are usually no ill or permanent effects from this drug. Any side effects you experience will taper off and cease when you stop receiving Neupogen shots. There have been cases of spleen rupture resulting in death, though this is exceedingly rare.

Who Should Avoid This Drug

Do not take this drug if:

  • You are pregnant or breastfeeding
  • You are allergic to Neupogen


Before your first injection of Neupogen, your doctor will order regular CBCs to get the levels of your platelets, red and white blood cells, and neutrophils. As treatment progresses, keep up with the recommended follow-up blood tests. These are important as they check the effectiveness of Neupogen and that you are getting the right dose.

If you are nursing or pregnant, discuss this with your doctor before taking Neupogen. There have not been enough studies done to determine the effect of this drug on breast milk or the human fetus.

The Bottom Line

Neupogen (or Neulasta) can be very effective for increasing the level of neutrophils in your body to reduce your risk of infection. It is still important, however, to be careful and practice measures which can lower your risk of an infection during chemotherapy such as careful hand washing and avoiding contact with those who are ill.