Tacrolimus and Danazol: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Tacrolimus
Danazol
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 tacrolimus exposure and an increased risk of toxicity
Interaction Deep Dive
One case report indicates that concurrent use of danazol and tacrolimus may lead to increased tacrolimus trough plasma levels and toxicity3. Concomitant use of tacrolimus with a weak or moderate CYP3A inhibitor like danazol may increase tacrolimus whole blood trough concentrations and the risk of serious toxicity (eg, neurotoxicity, QT prolongation). If coadministered, monitor tacrolimus blood levels and reduce the dose as needed, and monitor for tacrolimus-associated adverse effects 12.
Why it happens (mechanism)
Inhibition of CYP3A-mediated tacrolimus metabolism
Literature reports
1 report — tap to read
a) Danazol appears to have caused an increase in tacrolimus trough plasma levels in one case report. A 34-year-old woman who had undergone a renal transplant was treated with tacrolimus and steroids; after 11 months she had been weaned off the steroids and was maintained on oral tacrolimus 5 milligrams (mg) twice daily. Ten months later she developed idiopathic thrombocytopenic purpura and was treated with predniSONE 50 mg daily which was determined to be ineffective. Danazol 400 mg three times daily orally was begun and, by day 4, the patient had developed tremors, tacrolimus concentrations had increased to 2.7 nanograms/milliliter (ng/mL) (therapeutic range = 0.2 to 0.6 ng/mL), and serum creatinine rose over the next month from 124 to 212 micromoles/liter. The tacrolimus dose was reduced to 6 mg daily, but the plasma level remained high until danazol was stopped. Over the next two months the tacrolimus plasma level and serum creatinine returned to levels seen before danazol treatment was instituted. It is possible that danazol inhibited the hepatic metabolism of tacrolimus 3.
Common questions
Can I take Tacrolimus and Danazol together?
Increased tacrolimus exposure and an increased risk of toxicity Always confirm with your pharmacist or prescriber before making any change.
How serious is the Tacrolimus and Danazol 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.
Questions for your pharmacist
- Does my dose of Tacrolimus or Danazol 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: ENVARSUS XR(R) oral extended-release tablets, tacrolimus oral extended-release tablets. Veloxis Pharmaceuticals Inc (per FDA), Cary, NC, 2023. DailyMed
- Product Information: PROGRAF(R) oral capsules, oral granules for suspension, intravenous injection, tacrolimus oral capsules, oral granules for suspension, intravenous injection. Astellas Pharma US Inc (per FDA), Northbrook, IL, 2023. DailyMed
- Shapiro R, Venkataramanan R, Warty VS, et al: FK 506 interaction with danazol (letter). Lancet 1993; 341:1344-1345. PubMed
Keep reading about Tacrolimus
Keep reading about Danazol
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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