Estradiol and Pacritinib: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Pacritinib
Estradiol
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
Reduced efficacy of hormonal contraceptives
Interaction Deep Dive
Avoid concomitant use of pacritinib with hormonal contraceptives except for intrauterine systems containing levonorgestrel. The effectiveness of hormonal contraceptives, except for intrauterine systems containing levonorgestrel, may be reduced when used with pacritinib. If contraception is needed or desired, use an alternate contraceptive that is not affected by CYP3A4 inducers (eg, an intrauterine system) or additional nonhormonal contraceptive (eg, condoms) when treated concomitantly with pacritinib, and for 30 days after last dose of pacritinib1.
Why it happens (mechanism)
Induction of CYP3A4-substrate metabolism by pacritinib
Common questions
Can I take Estradiol and Pacritinib together?
Reduced efficacy of hormonal contraceptives Always confirm with your pharmacist or prescriber before making any change.
How serious is the Estradiol and Pacritinib 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 Estradiol or Pacritinib 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: VONJO(R) oral capsules, pacritinib oral capsules. CTI BioPharma Corp (per FDA), Seattle, WA, 2024. DailyMed
Keep reading about Pacritinib
Keep reading about Estradiol
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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