Idelalisib and Cobimetinib: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Idelalisib
Cobimetinib
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 cobimetinib exposure
Interaction Deep Dive
Avoid concomitant use of cobimetinib (a CYP3A substrate) with strong CYP3A inhibitors, as this may result in increased cobimetinib plasma concentrations. When the strong CYP3A inhibitor itraconazole was administered for 14 days concurrently with a single cobimetinib dose, the mean cobimetinib AUC increased by 6.7-fold and the mean Cmax increased by 3.2-fold1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of cobimetinib
Literature reports
1 report — tap to read
a) In a drug interaction study of 15 healthy volunteers, coadministration of the strong CYP3A inhibitor, itraconazole 200 mg once daily for 14 days with a single 10-mg cobimetinib dose increased mean cobimetinib AUC by 6.7-fold and mean Cmax by 3.2-fold 1.
Common questions
Can I take Idelalisib and Cobimetinib together?
Increased cobimetinib exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Idelalisib and Cobimetinib 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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Idelalisib or Cobimetinib 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 (1)
- Product Information: COTELLIC(R) oral tablets, cobimetinib oral tablets. Genentech USA Inc (per FDA), South San Francisco, CA, 2022. DailyMed
Keep reading about Idelalisib
Keep reading about Cobimetinib
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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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