Idelalisib
Idelalisib is a once-daily-to-twice-daily cancer pill (a kinase inhibitor) used with rituximab to treat relapsed chronic lymphocytic leukemia (CLL) in certain patients.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 1 clinical label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
Idelalisib (Zydelig) is a specialist cancer medicine, on the U.S. market since about 2014, that blocks PI3K delta, an enzyme B-cells (a type of white blood cell) need to grow and survive; it is used with rituximab for chronic lymphocytic leukemia that has come back, never as a first treatment. It is a hard drug to tolerate, and diarrhea, tiredness, fever and rash are what people notice most. Its boxed warning covers fatal and serious liver damage, severe diarrhea or colitis (bowel inflammation), pneumonitis (lung inflammation), infections and a hole in the bowel, so report worsening diarrhea, belly pain, new cough or fever right away.
Clinical pearls
- Liver tests run before starting and often every two weeks early on; problems usually surface in the first 12 weeks.
- Diarrhea on idelalisib can start at any time and responds poorly to anti-diarrhea medicines like loperamide, so call instead of self-treating.
- It boosts drugs cleared by the liver enzyme CYP3A, such as midazolam, while rifampin weakens it; check every new prescription.
- Women who could become pregnant need contraception until one month after the last dose, men with female partners until three months.
⚠️ FDA Boxed Warning — the FDA’s strongest safety alert ▾
Idelalisib can cause fatal and serious problems, so you need close monitoring and must report symptoms quickly.
- Liver damage: serious in 16% of treated patients. Liver tests are needed before and during treatment.
- Severe diarrhea or colitis (inflamed bowel): in 20% of patients.
- Pneumonitis (lung inflammation): in 4% of patients. Watch for breathing symptoms.
- Infections: fatal or serious in 48% of patients. Watch for fever or other signs.
- Intestinal perforation: a hole in the bowel wall, which can be fatal. Treatment is stopped if it occurs.
Your doctor may pause, lower, or stop the medicine if these occur.
Patient information guide A plain-language walkthrough of Idelalisib, written from its FDA label.
What Idelalisib is used for
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Idelalisib is a kinase inhibitor used for a specific blood cancer.
- Zydelig tablets, with rituximab, treat relapsed chronic lymphocytic leukemia (CLL) in patients for whom rituximab alone would be appropriate due to other conditions.
- Not for first-line treatment of any patient, including those with CLL, small lymphocytic lymphoma, follicular lymphoma, or other indolent non-Hodgkin lymphomas.
- Not recommended with bendamustine and rituximab, or with rituximab for follicular lymphoma, small lymphocytic lymphoma, or other indolent non-Hodgkin lymphomas.
How Idelalisib works
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Idelalisib blocks PI3K delta, an enzyme found in normal and cancerous B-cells. This enzyme helps relay signals that tell these cells to grow and survive.
It also interferes with signals that guide B-cells to the lymph nodes and bone marrow. In lab studies, this led to cancerous B-cells dying and growing less.
Idelalisib dosage
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Zydelig is a tablet taken by mouth twice a day, with or without food. Swallow it whole. Treatment generally continues until the disease progresses or side effects become unacceptable.
- Missed by less than 6 hours: take it as soon as possible, then continue as usual.
- Missed by more than 6 hours: skip it and take the next dose at the usual time.
- Your doctor may pause or lower the dose if side effects occur.
Dosing details from the FDA-approved label
From the Idelalisib prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- Recommended dosage (Zydelig, idelalisib)
- 150 mg administered orally twice daily with or without food until disease progression or unacceptable toxicity
- Swallow tablets whole. If a dose is missed by less than 6 hours, take it as soon as possible and take the next dose as usual; if missed by more than 6 hours, skip it and take the next dose at the usual time.
- Other severe or life-threatening adverse reactions (after interruption)
- Withhold Zydelig until resolution
- If resuming, reduce the dosage to 100 mg orally twice daily
- Permanently discontinue for recurrence of other severe or life-threatening Zydelig-related toxicity upon rechallenge.
- ALT/AST >5-20 × ULN or bilirubin >3-10 × ULN
- Withhold Zydelig
- Monitor at least weekly until ≤1 × ULN, then may resume at 100 mg BID
- ALT/AST >3-5 × ULN or bilirubin >1.5-3 × ULN: maintain dose and monitor at least weekly until ≤1 × ULN; discontinue permanently if ALT/AST >20 × ULN or bilirubin >10 × ULN.
- Severe diarrhea or hospitalization
- Withhold Zydelig
- Monitor at least weekly until resolved, then may resume at 100 mg BID
- Moderate diarrhea (increase of 4-6 stools per day over baseline): maintain dose and monitor at least weekly until resolved. Discontinue permanently for life-threatening diarrhea.
Read the label’s full dosing text
2 DOSAGE AND ADMINISTRATION Recommended dosage: 150 mg orally twice daily. ( 2.1 ) 2.1 Recommended Dosage The recommended dosage of Zydelig is 150 mg administered orally twice daily with or without food until disease progression or unacceptable toxicity. The optimal and safe dosing regimen for patients who receive treatment longer than several months is unknown. Swallow tablets whole. If a planned dose of Zydelig is missed by less than 6 hours, take the missed dose as soon as possible and take the next dose as usual. If a dose of Zydelig is missed by more than 6 hours, skip the missed dose and take the next dose at the usual time. 2.2 Dosage Modifications for Adverse Reactions Table 1 presents the dosage modification for specific adverse reactions. For other severe or life-threatening adverse reactions, withhold Zydelig until resolution. If resuming Zydelig after interruption for other severe or life-threatening toxicities, reduce the dosage to 100 mg orally twice daily. Permanently discontinue Zydelig for recurrence of other severe or life-threatening Zydelig-related toxicity upon rechallenge. Table 1 Dosage Modifications for Adverse Reactions Abbreviations: ANC: absolute neutrophil count; ALT, alanine aminotransferase; AST, aspartate aminotransferase; BID, twice daily; ULN, upper limit of normal; CMV, cytomegalovirus; DRESS, drug reaction with eosinophilia and systemic symptoms; PCR: polymerase chain reaction; PJP: Pneumocystis jirovecii pneumonia; SJS: Stevens-Johnson syndrome; TEN: toxic epidermal necrolysis ALT/AST >3–5 × ULN >5–20 × ULN >20 × ULN [see Warnings and Precautions (5.1) ] Maintain Zydelig dose. Monitor at least weekly until ≤1 × ULN. Withhold Zydelig. Monitor at least weekly until ALT/AST are ≤1 × ULN, then may resume Zydelig at 100 mg BID. Discontinue Zydelig permanently. Bilirubin >1.5–3 × ULN >3–10 × ULN >10 × ULN [see Warnings and Precautions (5.1) ] Maintain Zydelig dose. Monitor at least weekly until ≤1 × ULN. Withhold Zydelig. Monitor at least weekly until bilirubin is ≤1 × ULN, then may resume Zydelig at 100 mg BID. Discontinue Zydelig permanently. Diarrhea Moderate diarrhea: increase of 4–6 stools per day over baseline; severe diarrhea: increase of ≥7 stools per day over baseline. Moderate diarrhea Severe diarrhea or hospitalization Life-threatening diarrhea [see Warnings and Precautions (5.2) ] Maintain Zydelig dose.
Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →
Idelalisib side effects
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The most common side effects in trials were:
Common side effects
- Diarrhea
- Pneumonia (lung infection)
- Fever
- Fatigue
- Rash
- Cough
- Nausea
- Low white blood cell counts and raised liver enzymes on blood tests
When to get medical help
- Call your doctor right away for severe or persistent diarrhea, or belly pain, which could mean colitis or an intestinal perforation.
- Get help for new cough, shortness of breath, or trouble breathing, which could be pneumonitis (lung inflammation).
- Report fever, chills, or other signs of infection promptly.
- Tell your doctor about yellowing skin or eyes, dark urine, or severe belly pain, since liver problems can be serious.
- Seek urgent care for a severe skin reaction (such as widespread rash, blistering or peeling) or signs of a serious allergic reaction.
- Stop and call your doctor if you have severe stomach pain from a possible hole in the intestine.
Blood tests commonly show low neutrophils and raised liver enzymes (ALT and AST). Call your doctor promptly for severe diarrhea, breathing problems, signs of infection, liver symptoms, or severe skin reactions.
Idelalisib warnings and precautions
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The biggest risks are serious or fatal liver damage, severe diarrhea or colitis, pneumonitis, infections, and intestinal perforation. These are in a boxed warning.
- Liver tests are done often, especially in the first months.
- Diarrhea responds poorly to anti-diarrhea medicines and can start at any time.
- Severe skin reactions and serious allergic reactions can occur; treatment is stopped permanently if confirmed.
- Neutropenia (low neutrophils) requires blood count monitoring.
- It may cause fetal harm.
Idelalisib interactions
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Idelalisib is processed by the CYP3A enzyme, so some drugs interfere with it.
- Strong CYP3A inhibitors: can raise idelalisib levels and side-effect risk, so more monitoring is needed.
- Strong CYP3A inducers (such as rifampin): can lower levels and reduce effectiveness; avoid.
- Sensitive CYP3A substrates (such as midazolam): idelalisib can raise their levels; avoid.
- Drugs that harm the liver or cause diarrhea: avoid using at the same time.
Interactions listed in the FDA-approved label
From the Idelalisib prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
- Strong CYP3A inhibitors: Coadministration may increase idelalisib concentrations, which may increase the risk of exposure related adverse reactions. Use other drugs that are not strong CYP3A inhibitors. If unable to use alternative drugs, monitor patients more frequently for Zydelig adverse reactions.
- Strong CYP3A inducers: Coadministration may decrease idelalisib concentrations, which may reduce efficacy. Avoid coadministration of Zydelig with strong CYP3A4 inducers.
- Sensitive CYP3A substrates: Coadministration of Zydelig with a CYP3A substrate may increase the concentrations of this CYP3A substrate. Avoid coadministration of Zydelig with sensitive CYP3A substrates.
Read the label’s full interactions text
7 DRUG INTERACTIONS Strong CYP3A Inhibitors : Additional monitoring required if alternative therapy is not available. ( 7.1 ) Strong CYP3A Inducers : Avoid coadministration of strong CYP3A inducers. ( 7.1 ) CYP3A Substrates : Avoid coadministration of sensitive CYP3A substrates. ( 7.2 ) 7.1 Effects of Other Drugs on Zydelig Table 6 lists the potential effects of the coadministration of strong CYP3A modulators on Zydelig. Table 6 Drug Interactions with Zydelig that affect Idelalisib Concentrations Strong CYP3A Inhibitors Clinical Impact Coadministration with strong CYP3A inhibitors may increase idelalisib concentrations [see Clinical Pharmacology (12.3) ] . Increased idelalisib concentrations may increase the risk of exposure related adverse reactions. Prevention or Management Use other drugs that are not strong CYP3A inhibitors. If unable to use alternative drugs, monitor patients more frequently for Zydelig adverse reactions [see Adverse Reactions (6.1) ] . Strong CYP3A Inducers Clinical Impact Coadministration with strong CYP3A inducers may decrease idelalisib concentrations [see Clinical Pharmacology (12.3) ] . Decreased idelalisib concentrations may reduce efficacy. Prevention or Management Avoid coadministration of Zydelig with strong CYP3A4 inducers. 7.2 Effects of Zydelig on Other Drugs The coadministration of Zydelig with a CYP3A substrate may increase the concentrations of this CYP3A substrate. Avoid coadministration of Zydelig with sensitive CYP3A substrates [see Clinical Pharmacology (12.3) ].
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Idelalisib
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- Do not use with a history of serious allergic reaction to idelalisib or toxic epidermal necrolysis with any drug.
- Tell your doctor about liver problems; monitoring is needed.
- Pregnancy: may cause fetal harm; test before starting and use effective contraception (women for 1 month, men with female partners for 3 months after the last dose).
- Do not breastfeed during treatment and for 1 month after the last dose.
- Not established for children.
- Older adults (65+) had more serious side effects in trials.
What Idelalisib does in the body
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At a dose 2.7 times the maximum recommended dose, Zydelig did not prolong the QT/QTc interval, a measure of heart rhythm timing.
How your body processes Idelalisib
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Idelalisib reaches peak levels in the blood about 1.5 hours after a dose. A high-fat meal raised exposure about 1.4-fold, but it can be taken with or without food. It is broken down mainly by aldehyde oxidase and CYP3A, and its half-life is about 8 hours. Most is cleared through the feces, with some in urine.
Liver impairment can increase exposure up to 1.7-fold.
How to store Idelalisib
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Store between 20–30 °C (68–86 °F) with excursions permitted 15–30 °C (59–86 °F).
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Supplements & herbs that interact with Idelalisib
143 supplements and herbal products have documented interactions with Idelalisib in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 3
- Moderate · 100
- Minor · 40
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
Idelalisib: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Idelalisib — the kind of thing our pharmacy team would talk through with you at the counter.
What is idelalisib for?
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How do I take it?
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What side effects should I expect?
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When should I call my doctor right away?
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Can I take other medicines with it?
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What about pregnancy and breastfeeding?
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Is Idelalisib available over the counter?
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When was Idelalisib first available?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Idelalisib on HelloPharmacist
Idelalisib forms and strengths (how it comes)
Idelalisib is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Need a version that does not list lactose, a gluten source, a dye or gelatin? Inactive ingredients differ by manufacturer: see Idelalisib inactive ingredients by manufacturer.
Tablet
How this form is used
- Zydelig is used with rituximab for relapsed chronic lymphocytic leukemia (CLL) in patients for whom rituximab alone would be appropriate due to other conditions.
- Zydelig is taken by mouth twice daily, with or without food.
- Swallow Zydelig tablets whole.
- If a Zydelig dose is missed by less than 6 hours, take it as soon as possible, then take the next dose as usual.
- If a Zydelig dose is missed by more than 6 hours, skip it and take the next dose at the usual time.
Idelalisib on the U.S. market: products, makers and brands
How Idelalisib appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
1 company lists 2 Idelalisib product records with the FDA, mostly as tablet; the earliest marketing or approval year on record is 2014. Brand names on the directory include Zydelig; the rest are generics.
Also listed with the FDA, not a patient dose form: Powder (2) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Compare Idelalisib products
A representative set of FDA-listed product records for Idelalisib — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Tablet | ||||
| 100 mg | Oral | Gilead Sciences, Inc. | NDA | View NDC → |
| 150 mg | Oral | Gilead Sciences, Inc. | NDA | View NDC → |
Showing 2 of 2 products — FDA National Drug Code Directory. See every product, package size and price: browse all 2 Idelalisib NDCs →
Idelalisib side effects reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Idelalisib — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Idelalisib in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
Idelalisib FDA approval history
How Idelalisib went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Idelalisib recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
The FDA’s enforcement reports list no Idelalisib recalls since July 2021.
✅No Idelalisib recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 1544460 1 dose form · 2 strengths
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Dose form (SCDF) Oral Tablet RxCUI 1544464In current FDA listings
Look up RxCUI 1544460 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
Idelalisib supply and shortage status
Whether Idelalisib is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
Idelalisib brand names
Idelalisib is sold under one brand name in the FDA directory — Zydelig. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Idelalisib: manufacturers and labelers
One company lists Idelalisib products with the FDA. By number of product records, the largest are Gilead Sciences, Inc.. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Idelalisib drug class (RxNorm)
Idelalisib belongs to the Kinase Inhibitor class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for this Idelalisib page
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Gilead Sciences, Inc. is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →