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What is ZARXIO?

ZARXIO is a man-made form of granulocyte colony-stimulating factor (G-CSF) called filgrastim. G-CSF is a substance produced by the body. It stimulates the growth of neutrophils, a type of white blood cell that is important in the body's fight against infection.

Some cancer treatments decrease white blood cell counts, which may increase the risk of infection. A low level of neutrophils is known as neutropenia.

Learn more about ZARXIO


What is a biosimilar?

ZARXIO is the first biosimilar approved in the US.

A biosimilar is a medication that has been approved by the FDA as being highly similar to a previously approved biologic medication. Biosimilars may be available at a lower cost than the referenced biologic medication.

What is ZARXIO approved to treat?

ZARXIO is a prescription medicine used to help reduce the chance of infection due to a low white blood cell count in patients with certain types of cancer (nonmyeloid) who are receiving chemotherapy that can cause fever and a low blood cell count.

How is ZARXIO administered?

ZARXIO injections can be given by a healthcare provider by subcutaneous (under the skin) injection or by intravenous (IV) infusion. Your healthcare provider may decide subcutaneous injections can be given at home by you or your caregiver. If ZARXIO is given at home, see the detailed Instructions for Use that come with your prescription for information on how to prepare and inject a dose of ZARXIO.

You and your caregiver will be shown how to prepare and inject ZARXIO before you use it.

Watch the administration video

How do I administer a ZARXIO injection?

Your healthcare provider will provide you with training on how to inject ZARXIO. They will explain what dose you should administer and how frequently it should be injected. You should not attempt to give yourself a subcutaneous injection until you have received the appropriate training from your healthcare provider.

Watch the administration video

How do I prepare for a ZARXIO injection?

In addition to the prefilled syringe that is included in your pack, you will need:

  • 1 alcohol wipe
  • 1 cotton ball or gauze
  • Sharps disposal container
  • 1 adhesive bandage

You should not inject a dose of ZARXIO less than 0.3 mL (180 mcg) from a ZARXIO prefilled syringe. A dose less than 0.3 mL cannot be accurately measured using the ZARXIO prefilled syringe.

Learn more about administration

How should I store ZARXIO?

  • Store ZARXIO in the refrigerator between 36°F to 46°F (2°C to 8°C)
  • Protect from freezing ZARXIO. If frozen, thaw in the refrigerator before use. Throw away (dispose of) ZARXIO if it has been frozen more than 1 time
  • Store ZARXIO in the original pack to protect it from light
  • Avoid shaking ZARXIO
  • Take ZARXIO out of the refrigerator 30 minutes before use and allow it to reach room temperature before preparing an injection
  • ZARXIO may be allowed to reach room temperature for up to 4 days. Throw away (dispose of) any ZARXIO that has been left at room temperature for longer than 4 days
  • After you inject your dose, throw away (dispose of) any unused ZARXIO left in the prefilled syringe. Do not save unused ZARXIO in the prefilled syringe for later use

Keep ZARXIO and all medicines out of the reach of children.

How do I throw away (dispose of) used ZARXIO prefilled syringes?

After you inject your dose, throw away (dispose of) any unused ZARXIO left in the prefilled syringe. Do not save unused ZARXIO in the prefilled syringe for later use.

Put your used prefilled syringes in an FDA-cleared sharps disposal container (see Figure A) right away after use. Do not throw away (dispose of) ZARXIO prefilled syringes in your household trash.

sharps container

If you do not have an FDA-cleared sharps disposal container, you may use a household container that:

  • Is made of a heavy-duty plastic
  • Can be closed with a tight-fitting, puncture-resistant lid, without sharps being able to come out
  • Is upright and stable during use
  • Is leak-resistant
  • Is properly labeled to warn of hazardous waste inside the container

When your sharps disposal container is almost full, you will need to follow your community guidelines for the right way to dispose of your sharps disposal container. There may be state or local laws about how you should throw away used needles, syringes, and prefilled syringes. For more information about safe sharps disposal, and for specific information about sharps disposal in the state that you live in, go to the FDA's website at

Important: Always keep the sharps disposal container out of the reach of children.

Reference: ZARXIO Prescribing Information. Sandoz Inc. September 2022.