What the FDA labels say about taking them together
Diltiazem and ranitidine
Diltiazem's FDA label of August 7, 2026 names ranitidine in its drug interactions section; the ranitidine label PlainMeds reads does not name diltiazem. The diltiazem label: “… 1-week course of cimetidine 1200 mg/day and a single dose of diltiazem 60 mg. Ranitidine produced smaller, nonsignificant increases.”
Check it at the source: the diltiazem FDA label on DailyMed (effective August 7, 2026, Bausch Health US, LLC); the ranitidine FDA label on DailyMed (effective May 1, 2026, Amneal Pharmaceuticals of New York LLC).
What does the diltiazem label say about ranitidine?
Diltiazem label, drug interactionsA study in six healthy volunteers has shown a significant increase in peak diltiazem plasma levels (58%) and AUC (53%) after a 1-week course of cimetidine 1200 mg/day and a single dose of diltiazem 60 mg. Ranitidine produced smaller, nonsignificant increases.
Source: FDA drug label (Cardizem Cd, NDA020062), Bausch Health US LLC, effective December 10, 2025 (SPL set 1042fa13-e6af-46b9-8008-6c941f0978b1), via openFDA
Source: FDA drug label (Cardizem, NDA018602), Bausch Health US LLC, effective April 30, 2025 (SPL set f3e7ecef-f360-4987-a4f5-933214130ab2), via openFDA
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 ranitidine label say about diltiazem?
Ranitidine's label (effective May 1, 2026) does not name diltiazem in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Ranitidine), Amneal Pharmaceuticals of New York LLC, effective May 1, 2026 (SPL set b38a3332-5c54-453f-aeb7-070f830955c2), 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 | Ranitidine | |
|---|---|---|
| Labeled for | High blood pressure, Angina, Atrial fibrillation | Acid reflux and ulcers |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.144 per capsule 24h ER(cd) 120 mg capsule | n/a |
| 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