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What the FDA labels say about taking them together

Cimetidine and sirolimus

Sirolimus's FDA label of January 28, 2026 names cimetidine in its drug interactions section; the cimetidine label PlainMeds reads does not name sirolimus. The sirolimus label: “Drugs that could increase sirolimus blood concentrations: Bromocriptine, cimetidine, cisapride, clotrimazole, danazol, diltiazem, fluconazole, letermovir, protease inhibitors, metoclopramide, nicardipine …”

Check it at the source: the cimetidine FDA label on DailyMed (effective July 15, 2026, Mylan Pharmaceuticals Inc.); the sirolimus FDA label on DailyMed (effective January 28, 2026, Glenmark Pharmaceuticals Inc., USA).

What does the cimetidine label say about sirolimus?

Cimetidine's label (effective July 15, 2026) does not name sirolimus 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 sirolimus label say about cimetidine?

Sirolimus label, drug interactions

Drugs that could increase sirolimus blood concentrations: Bromocriptine, cimetidine, cisapride, clotrimazole, danazol, diltiazem, fluconazole, letermovir, protease inhibitors (e.g., HIV and hepatitis C that include drugs such as ritonavir, indinavir, boceprevir, and telaprevir), metoclopramide, nicardipine, troleandomycin, verapamil

Source: FDA drug label (sirolimus), Glenmark Pharmaceuticals Inc., USA, effective January 28, 2026 (SPL set 57fb4d90-3ccb-4a69-af1e-53be83f7a504), 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

18Cimetidine generic labelers
17Sirolimus generic labelers
CimetidineSirolimus
Labeled forAcid reflux and ulcersOrgan transplant rejection
Boxed warningNoYes
Pharmacy cost (NADAC)$0.236 per tablet 300 mg tablet$0.723 per tablet 1 mg tablet
Shortage nowNo current entryNo 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?