Idelalisib
Idelalisib is a targeted cancer medication that works by inhibiting PI3Kδ, a specific protein important for B-cell survival and proliferation. It is used to treat certain blood cancers originating from B-cells by blocking the signals that cancer cells need to grow and survive.
A PI3Kδ inhibitor that treats certain B-cell cancers by blocking cancer cell growth and survival signals.
This medication carries a boxed (black box) warning — the strongest type of FDA warning. Review the full prescribing information before use.
Key facts at a glance
- ATC
- L01EM01
- RxNorm
- 1544460
- Generic
- Idelalisib
- Class
- atc-l01
- Brands
- Zydelig
- Availability
- rx
- Lactation
- unknown
- Routes
- oral
- Forms
- tablet
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Idelalisib is used to treat adults with chronic lymphocytic leukemia (CLL), follicular lymphoma, and small lymphocytic lymphoma (SLL) who have received prior therapy.
Idelalisib inhibits phosphatidylinositol 3-kinase delta (PI3Kδ), an enzyme expressed in normal and malignant B-cells that plays a key role in cell survival and proliferation. By blocking this enzyme, idelalisib induces apoptosis (programmed cell death) and inhibits tumor cell growth.
Idelalisib carries boxed warnings for serious liver toxicity, diarrhea, and intestinal inflammation. Regular monitoring of liver function and blood counts is required. Patients should report any signs of liver problems, severe diarrhea, or infections immediately. This medication may increase the risk of serious infections and should only be prescribed by healthcare providers experienced in cancer treatment.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 26, 2026. · Read our editorial policy