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Generic name: pegaspargasepeg-ah-SPAR-jase ]
Drug class: Miscellaneous antineoplastics

Medically reviewed by on Jul 21, 2022. Written by Cerner Multum.

What is Oncaspar?

Oncaspar is used in combination with other medicines to treat acute lymphoblastic leukemia.

Oncaspar is also used to treat allergic reactions to another cancer medicine called asparaginase.

Oncaspar may also be used for purposes not listed in this medication guide.


You should not use Oncaspar if you are allergic to Oncaspar or asparaginase, if you have ever received asparaginase and it caused pancreatitis, severe bleeding, or a blood clot.

Before taking this medicine

You should not use this medicine if you are allergic to Oncaspar or asparaginase, or if you have ever received asparaginase and it caused any of the following conditions:

  • a blood clot;

  • pancreatitis;

  • severe bleeding; or

  • a severe allergic reaction.

Tell your doctor if you have ever had:

You may need to have a negative pregnancy test before starting this treatment.

Oncaspar may harm an unborn baby. Use effective birth control to prevent pregnancy while you are using this medicine and for at least 3 months after your last dose. Tell your doctor if you become pregnant.

Oncaspar can make hormonal birth control less effective, including birth control pills, injections, implants, skin patches, and vaginal rings. To prevent pregnancy while using this medicine, use a barrier form of birth control: condom, diaphragm, cervical cap, or contraceptive sponge.

Do not breastfeed while using this medicine, and for at least 3 months after your last dose.

How is Oncaspar given?

Oncaspar is injected into a muscle or given as an infusion into a vein. A healthcare provider will give you this injection.

You will be watched closely for at least 1 hour to make sure you do not have an allergic reaction.

Oncaspar can lower your blood cell counts. Your blood will need to be tested often. Your cancer treatments may be delayed based on the results.

Your liver function may also need to be checked.

What happens if I miss a dose?

Call your doctor for instructions if you miss an appointment for your Oncaspar.

What happens if I overdose?

Since Oncaspar is given by a healthcare professional in a medical setting, an overdose is unlikely to occur.

What should I avoid while receiving Oncaspar?

Avoid activities that may increase your risk of bleeding or injury. Use extra care to prevent bleeding while shaving or brushing your teeth.

Oncaspar side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Oncaspar may cause serious side effects. Call your doctor at once if you have:

  • easy bruising, unusual bleeding, purple or red spots under your skin;

  • low white blood cell counts--fever, mouth sores, skin sores, sore throat, cough, trouble breathing;

  • signs of liver or pancreas problems--loss of appetite, upper stomach pain (that may spread to your back), nausea or vomiting, fast heart rate, dark urine, jaundice (yellowing of the skin or eyes);

  • high blood sugar--increased thirst, increased urination, dry mouth, fruity breath odor; or

  • signs of a blood clot--sudden numbness or weakness, problems with vision or speech, swelling or redness in an arm or leg.

Your cancer treatments may be delayed or permanently discontinued if you have certain side effects.

Common side effects of Oncaspar may include:

  • blood clot symptoms;

  • an allergic reaction;

  • pancreas or liver problems;

  • high blood sugar; or

  • low white blood cells.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Oncaspar?

Other drugs may affect Oncaspar, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Frequently asked questions

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.