What the FDA labels say about taking them together
Diltiazem and ritonavir
Ritonavir's FDA label of July 23, 2026 names diltiazem in its drug interactions section; the diltiazem labels PlainMeds reads (4) do not name ritonavir. The ritonavir label: “Caution is warranted and clinical monitoring of patients is recommended. A dose decrease may be needed for these drugs when co-administered with ritonavir.”
Check it at the source: the diltiazem FDA label on DailyMed (effective August 7, 2026, Bausch Health US, LLC); the ritonavir FDA label on DailyMed (effective July 23, 2026, AbbVie Inc.).
What does the diltiazem label say about ritonavir?
Diltiazem's label (effective August 7, 2026) and its 3 other brand-application labels do not name ritonavir 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 ritonavir label say about diltiazem?
Ritonavir label, drug interactionsConcomitant Drug Class/Drug Name: Calcium channel blockers: diltiazem, nifedipine, verapamil; Effect on Concentration of Ritonavir or Concomitant Drug: ↑ calcium channel blockers; Clinical Comment: Caution is warranted and clinical monitoring of patients is recommended. A dose decrease may be needed for these drugs when co-administered with ritonavir.
Source: FDA drug label (Norvir), AbbVie Inc., effective July 23, 2026 (SPL set 2849298e-de6e-47bb-8194-56e075b33fc3), 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 | Ritonavir | |
|---|---|---|
| Labeled for | High blood pressure, Angina, Atrial fibrillation | HIV |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.144 per capsule 24h ER(cd) 120 mg capsule | $0.607 per tablet 100 mg tablet |
| Shortage now | A presentation being discontinued | A presentation being discontinued |
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