Zarxio: 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, which increases your risk of infection. 

Zarxio (chemical name: filgrastim-sndz) 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 Zarxio prescribing information. 

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

Neupogen and Neulasta are other granulocyte colony-stimulating factors. Zarxio is a biosimilar of Neupogen.

Zarxio is given intravenously or as an injection once per day for up to two weeks after every chemotherapy dose.

If your doctor decides injections are right for you, you may be able to administer them at home.

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

The most common side effects of Zarxio 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 Zarxio. 

Because Zarxio 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 Zarxio.

Members of our community discuss their experiences with Zarxio 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.

“Bone pain is gone — Claritin with the Zarxio shot definitely helped. I can walk down the stairs with no pain.” —LivLife

“I’m definitely getting sinus pressure after Zarxio shots…Still have some headaches which I think is dehydration (even though I feel like I'm drinking so much water). A liter of coconut water helped a lot yesterday so I just went and bought a few more.” —nimmy1976

“Giving myself the Zarxio shots has been interesting, but luckily no problems so far.” —ACchaos

Read more in our Zarxio discussion forum.

The cost of Zarxio 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 Zarxio infusions.

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

If you have trouble paying for Zarxio, ask your care team about financial assistance programs that may be able to help. Sandoz has a patience assistance program, too.

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