Neupogen: What to Expect, Side Effects, and More

If you’re receiving chemotherapy to treat breast cancer, you may have a low white blood cell count, leaving you at a higher risk of infection. 

Neupogen (chemical name: filgrastim) is a man-made form of granulocyte colony-stimulating factor (G-CSF). G-CSF is produced by the body to stimulate the growth of neutrophils, a type of white blood cell that helps your body fight infection.

See Neupogen prescribing information. 

Granulocyte colony-stimulating factors help the body make more neutrophils, a type of white blood cell.

Zarxio (chemical name: filgrastim-sndz) and Neulasta (chemical name: pegfilgrastim) are other granulocyte colony-stimulating factors. Zarxio is a biosimilar of Neupogen.

Neupogen is given intravenously or as an injection once per day for up to two weeks after each chemotherapy course.

Like almost all breast cancer medicines, Neupogen can cause side effects, some of them severe.

The most common side effects of Neupogen are:

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  bone and joint pain

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  muscle pain

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  headache

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  nosebleeds

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  spleen rupture

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  pain in the upper left part of the stomach or tip of the left shoulder

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  fever

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  trouble breathing

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  rash

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  itching

Your doctor may prescribe a non-steroidal anti-inflammatory drug (NSAID) such as ibuprofen or naproxen to treat bone pain caused by Neupogen. 

Because Neupogen stimulates the immune system, excess histamines may be present in your body. Your doctor also may recommend an antihistamine such as Claritin (chemical name: loratadine) — NOT Claritin-D — to ease bone pain caused by Neupogen.

Members of our community discuss their experiences with Neupogen in the community forum. Here are some of their comments. Remember, it's very important to talk to your doctor about any side effects you're having and ask about ways to manage them.

“With the Neupogen, I had bone pain, and with the Neulasta, muscle pain. But the muscle pain usually only lasted a couple of days, whereas with the Neupogen, the bone pain lasted a lot longer.” —mom2acat

“My counts are all up again — reds are normal and WBC & neutrophils are high — no wonder, after six shots of Neupogen! I'm two weeks from the last chemo and just starting to feel a bit stronger and the light's back on!” —Carolben

“The neupogen worked wonders for my WBC's.  Hope it does the same for you.  But I remember the bone pain I felt after the neupogen shots.” —SammieKay

Read more in our Neupogen discussion forum.

The cost of Neupogen may vary. The price you’ll pay depends on your health insurance provider and plan, where you live, and the pharmacy you use.

You may also be charged for the office visits required for Neupogen infusions.

Note: Your insurance company may require you to get prior authorization before covering Neupogen. 

If you have trouble paying for Neupogen, ask your care team about financial assistance programs that may be able to help. Amgen offers Amgen Assist to help offset the cost. 

Learn more about financial assistance and medicine cost-lowering tips.