What the FDA labels say about taking them together
Cimetidine and tacrolimus
Tacrolimus's FDA label of July 17, 2026 names cimetidine in its drug interactions section; the cimetidine label PlainMeds reads does 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 cimetidine FDA label on DailyMed (effective July 15, 2026, Mylan Pharmaceuticals Inc.); the tacrolimus FDA label on DailyMed (effective July 17, 2026, Stellon Biotech Inc.).
What does the cimetidine label say about tacrolimus?
Cimetidine's label (effective July 15, 2026) does 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 (Cimetidine), Mylan Pharmaceuticals Inc., effective July 15, 2026 (SPL set 06c0a509-026f-44e0-9975-a94a8de51d43), via openFDA; the full label on DailyMed
What does the tacrolimus label say about cimetidine?
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
| Cimetidine | Tacrolimus | |
|---|---|---|
| Labeled for | Acid reflux and ulcers | Organ transplant rejection, Eczema (atopic dermatitis) |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.236 per tablet 300 mg tablet | $0.970 per gram 0.1% ointment |
| Shortage now | No current entry | 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