Idelalisib and Budesonide: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Idelalisib
Budesonide
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased exposure of CYP3A substrate
Interaction Deep Dive
Avoid coadministration of idelalisib (a strong CYP3A inhibitor) and a sensitive CYP3A substrate as this may increase exposure of the CYP3A substrate and increase the risk of adverse effects. During a drug interaction study, coadministration of idelalisib and midazolam (CYP3A substrate) resulted in a 5.4-fold increase in midazolam AUC and a 2.4 fold increase in midazolam Cmax12.
Why it happens (mechanism)
Inhibition of CYP3A-mediated metabolism by idelalisib
Literature reports
2 reports — tap to read
a) In a pharmacokinetic study (N=23), administration of a single midazolam 5 mg dose following multiple doses of idelalisib 150 mg orally twice daily resulted in significant increases in midazolam exposure (138% increase in Cmax and 437% increase in AUC) compared with midazolam alone 2.
b) Coadministration of diazePAM and idelalisib for 10 days in a 71-year-old woman resulted in altered mental status and respiratory failure. She was receiving diazePAM 5 mg twice daily, venlafaxine XL 300 mg daily, and had initiated idelalisib 150 mg twice daily 10 days prior to presentation. The patient presented with lethargy, speaking difficulty, and progressive weakness inhibiting her ability to stand. Arterial blood gas analysis revealed respiratory acidosis and type II respiratory failure (pH 7.3, PO2 113 mmHg, PCO2 63 mmHg, and bicarbonate 31 mEq/L). Venlafaxine was reduced to 37.5 mg daily, diazePAM was changed to LORazepam 0.5 mg twice daily, and full-dose idelalisib was restarted with no further sequelae 3.
Common questions
Can I take Idelalisib and Budesonide together?
Increased exposure of CYP3A substrate Always confirm with your pharmacist or prescriber before making any change.
How serious is the Idelalisib and Budesonide interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Idelalisib or Budesonide need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (3)
- Product Information: ZYDELIG(R) oral tablets, idelalisib oral tablets. Gilead Sciences Inc (per FDA), Foster City, CA, 2018. DailyMed
- Jin F, Robeson M, Zhou H, et al: Clinical drug interaction profile of idelalisib in healthy subjects. J Clin Pharmacol 2015; 55(8):909-919. PubMed
- Bossaer JB & Chakraborty K: Drug interaction between idelalisib and diazepam resulting in altered mental status and respiratory failure. J Oncol Pharm Pract 2017; 23(6):470-472. DOI
Keep reading about Idelalisib
Keep reading about Budesonide
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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