Using Neupogen to Treat Low Neutrophil Count During Chemotherapy

Uses and side effects during chemotherapy

Neupogen (filgrastim) is a drug given to some people receiving chemotherapy who have or may develop a low neutrophil count (chemotherapy-induced neutropenia.) Neutrophils are a type of white blood cell that help 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).

A syringe and two vials of chemotherapy drugs
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With breast cancer chemotherapy, Neupogen is often given preventively a day after chemotherapy infusions that are likely to severely reduce your neutrophil count, such as double dose Cytoxan (cyclophosphamide) and Adriamycin (doxorubicin). 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. Learn about how and why Neupogen is given, the possible side effects you may experience, and the differences between Neupogen and a similar drug called Neulasta.

Neupogen With Breast Cancer

Chemotherapy for breast cancer affects all the rapidly dividing cells in your body, including the cells in the bone marrow that 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) that poses the most risk. During chemotherapy, your oncologist will check your complete blood count (CBC) often.

How Neupogen Works

Usually, your body produces a protein (granulocyte colony-stimulating factor) that stimulates the production of neutrophils in a process called hematopoiesis. But chemotherapy for breast cancer may affect the bone marrow and decrease white-blood-cell precursors, and your body's production of this protein may not be enough to compensate for this decrease. Your CBC may reveal that your absolute neutrophil 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.


Neupogen is given as daily injections until your white blood cell count returns to normal. Often this will mean three or four injections, but sometimes up to 10 injections are needed. When properly given, these injections will not hurt. This drug can also be given through an intravenous infusion (IV). There is a risk of allergic reactions with this medication, and some healthcare providers ask that you have the injections either at the cancer center or your local clinic. Other healthcare providers prescribe the injections to be given at home as long as people are familiar with the potential for an allergic reaction, know the symptoms to look for, and have medical care available nearby.

Neupogen vs. Neulasta

You may be given a choice as to whether you would prefer to receive Neupogen or Neulasta (pegfilgrastim), a similar drug. Overall, the effectiveness and safety profile of the two drugs is similar, though Neulasta may be somewhat more effective at preventing severe neutropenia. While Neupogen is given as daily injections, Neulasta is given as a one-time shot the day after chemotherapy.

Since it must be given 14 days prior to the next infusion, only Neupogen is an option for those receiving weekly chemotherapy.

Bone pain is common with both medications, but slightly more common with Neulasta.

Side Effects, Risks, and Contraindications

As with any medications, Neupogen injections may give rise to side effects. There are also some potential risks as well as cases in which the drug should not be given.

Side Effects

Not everyone will have side effects on Neupogen, but both bone pain and 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, upper legs, and pelvis.

Usually, treatment is not needed for bone pain, but ask your healthcare provider about this side effect ahead of time if it concerns you.

Some oncologists recommend taking Tylenol (acetaminophen ) or Advil (ibuprofen) if the pain is bothersome but, since medications can interact or pose problems if your liver or kidneys are not working properly, it is important to clear any medication with your own oncologist ahead of time. Many people find that soaking in a warm bath helps alleviate much of the bone pain.

A low platelet count (thrombocytopenia) may also occur, and some people develop nosebleeds or red spots (petechiae) on their skin. Shortness of breath or a cough may also occur for some people. On blood tests, a transient elevation of lactate dehydrogenase (a type of protein) and alkaline phosphatase may occur.


Neupogen is a relatively safe drug used for many types of neutropenia, and there are usually no ill or permanent effects from this drug. Any side effects you experience will usually 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.


Contraindications, or situations in which Neupogen should not be used, include women who are pregnant or breastfeeding and people who are allergic to Neupogen.

When To Call Your Healthcare Provider

Reactions may sometimes occur. Call your healthcare provider right away if you 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 healthcare provider if you note any chest pain, heart palpitations, or unusual fatigue or lethargy.

Before Your First Injection

Before your first injection of Neupogen, your healthcare provider will order regular CBCs to assess 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 to check the effectiveness of Neupogen and that you are getting the right dose.

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

Neupogen is Only One Step in Lowering Infection Risk

Prior to the widespread use of Neupogen or Neulasta, the risk of infection during chemotherapy was foremost in most oncologists' (and patients') minds. Yet even when your white blood cell count is improved by Neupogen, reducing the risk of infections is still extremely important. Not only may your white count still drop, but the white blood cells you have won't necessarily work as well as usual. Serious infections can and do occur while people are receiving Neupogen, so it's important to educate yourself about your risk. Some methods of lowering risk (such as avoiding crowded malls) may seem obvious, while others (such as avoiding some types of cheese and certain pets) may not.

A Word From Verywell

Neupogen can be very effective for increasing the level of neutrophils in your body to reduce your risk of infection. Many people experience some bone pain and a fever, but this is usually very mild. Fortunately, the medication is needed only as long as you are receiving chemotherapy and can then be discontinued.

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5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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