What the FDA labels say about taking them together
Diltiazem and tacrolimus
Tacrolimus's FDA label of July 17, 2026 names diltiazem in its drug interactions section; the diltiazem labels PlainMeds reads (4) do not name tacrolimus. The tacrolimus label: “Monitor tacrolimus whole blood trough concentrations and reduce ASTAGRAF XL dose if needed.”
Check it at the source: the diltiazem FDA label on DailyMed (effective August 7, 2026, Bausch Health US, LLC); the tacrolimus FDA label on DailyMed (effective July 17, 2026, Stellon Biotech Inc.).
What does the diltiazem label say about tacrolimus?
Diltiazem's label (effective August 7, 2026) and its 3 other brand-application labels do not name tacrolimus in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (TIAZAC EXTENDED RELEASE), Bausch Health US, LLC, effective August 7, 2026 (SPL set c567fe7e-887e-4291-a0d1-2dd3f25cbf25), via openFDA; the full label on DailyMed
What does the tacrolimus label say about diltiazem?
Tacrolimus label, drug interactionsDrug/Substance Class or Name: Mild or Moderate CYP3A Inhibitors: Clotrimazole, antibiotics (e.g., erythromycin, fluconazole), calcium channel blockers (e.g., verapamil, diltiazem, nifedipine, nicardipine), amiodarone, danazol, ethinyl estradiol, cimetidine, lansoprazole and omeprazole; Drug Interaction Effect: May increase tacrolimus whole blood trough concentrations and increase the risk of serious adverse reactions (e.g., neurotoxicity, QT prolongation) [see,,)].; Recommendations: Monitor tacrolimus whole blood trough concentrations and reduce tacrolimus dose if needed [ see,) and ].
Envarsus Xr label (Veloxis Pharmaceuticals, Inc, February 26, 2025), drug interactionsDrug/Substance Class or Name: Mild or Moderate CYP3A Inhibitors, such as: antibiotics (e.g., erythromycin), calcium channel blockers (e.g., verapamil, diltiazem, nifedipine, nicardipine), amiodarone, danazol, ethinyl estradiol, cimetidine, lansoprazole and omeprazole, azole antifungals (e.g., clotrimazole, fluconazole, isavuconazole), imatinib, nilotinib, letermovir; Drug Interaction Effect: May increase tacrolimus whole blood trough concentrations and increase the risk of serious adverse reactions (e.g., neurotoxicity, QT prolongation) [see,, ].; Recommendations: Monitor tacrolimus whole blood trough concentrations and reduce ENVARSUS XR dose if needed [see and ].
Source: FDA drug label (Astagraf Xl, NDA204096), Astellas Pharma US, Inc., effective January 14, 2026 (SPL set 550a5cd4-fbf2-4c09-b577-6bde8fcbdf6e), via openFDA
Source: FDA drug label (Envarsus Xr, NDA206406), Veloxis Pharmaceuticals, Inc, effective February 26, 2025 (SPL set de2315b0-6344-43ac-9aea-3e3b68d828e7), via openFDA
Source: FDA drug label (Tacrolimus), Stellon Biotech Inc., effective July 17, 2026 (SPL set 6b89e8a4-9f11-42e3-8e79-fe617e7c461f), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Diltiazem | Tacrolimus | |
|---|---|---|
| Labeled for | High blood pressure, Angina, Atrial fibrillation | Organ transplant rejection, Eczema (atopic dermatitis) |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.144 per capsule 24h ER(cd) 120 mg capsule | $0.970 per gram 0.1% ointment |
| Shortage now | A presentation being discontinued | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once