Neulasta: What to Expect, Side Effects, and More

After you have chemotherapy to treat breast cancer, your doctor may prescribe Neulasta (chemical name: pegfilgrastim). It’s a protein used to prevent neutropenia — a lack of certain white blood cells — that is caused by chemotherapy.

Neulasta works by helping your body make white blood cells, which can then reduce the risk of infection during chemotherapy.

See Neulasta prescribing information.

So, what does Neulasta do? It stimulates the immune system to help the body make more neutrophils, a type of white blood cell. This process also creates histamines, which may cause bone pain. If you do start to suffer from bone pain, your doctor may recommend an antihistamine, such as Claritin, to help. 

Your doctor may also prescribe a non-steroidal anti-inflammatory drug (NSAID), such as ibuprofen or naproxen.

Neulasta can be given as an injection or as a patch applied to your skin. The Neulasta shot is usually given once during each chemotherapy cycle. It should not be given within 14 days before you receive chemotherapy or less than 24 hours after you receive chemotherapy.

The Neulasta patch, called Neulasta Onpro, should be refrigerated until it’s ready to be used. The patch is applied by a healthcare professional right after your chemotherapy infusion. It automatically delivers the dose of Neulasta over 45 minutes, approximately 27 hours after the patch is applied. Once the dose is complete, you remove the patch. 

You should avoid traveling, operating machinery, and driving while wearing the patch.

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

The most common Neulasta side effects are:

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  muscle pain in your arms or legs

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  bone and joint pain

You should call your doctor if you have any of the following side effects of Neulasta:

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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

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  headache

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  weakness

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  constipation

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  vomiting

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  swelling

Neulasta is a  biologic medicine, which means it's made from living organisms, in this case the bacteria Escherichia coli.

Biosimilars are almost identical to a biologic medicine that is already approved by the U.S. Food and Drug Administration (or similar organizations in other countries). It can help to think of a biosimilar as a generic version of a biologic drug, though that comparison isn’t completely accurate.

Six Neulasta biosimilars have been approved by the FDA:

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  Fulphila (chemical name: pegfilgrastim-jmdb)

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  Udenyca (chemical name: pegfilgrastim-dbqv)

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  Ziextenzo (chemical name: pegfilgrastim-bmez)

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  Nyvepria (chemical name: pegfilgrastim-apgf)

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  Fylnetra (chemial name: pegfilgrastim-pbbk)

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  Stimufend (chemical name: pegfilgrastim-fpgk)

Research shows that all the biosimilars work the same way Neulasta does and their side effects are the same as Neulasta’s.

All the biosimilars are given as injections. Udenyca is also available as an autoinjector — a pen that automatically injects the medicine by pushing the tip of it against your skin, much like how an EpiPen works.

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

“No side effects yet after Neulasta shot. Have been taking Claritin the day before, the day after, and this morning. Hoping for little or no side effects!” —joanmj58

“I had some episodes of severe pain after chemo, but it was caused by the Neulasta shot, not the actual chemo. I've been on Femara for two years, with very few side effects.” —mustlovepoodles

“I was very afraid of the Neulasta shot, but I did not have any side effects from it.” —Carrol2

Read more in the Neulasta discussion forum.

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

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

If you have trouble paying for Neulasta, ask your care team about financial assistance programs that may be able to help.

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