Diltiazem and Nifedipine interaction
Diltiazem and Nifedipine: the Nifedipine prescribing label describes an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Nifedipine label · effective 2026-02-05
Calcium Channel Blockers Diltiazem: Pre-treatment of healthy volunteers with 30 mg or 90 mg t.i.d. diltiazem p.o. increased the AUC of nifedipine after a single dose of 20 mg nifedipine by factors of 2.2 and 3.1, respectively.
Caution should be exercised when co-administering diltiazem and nifedipine and a reduction of the dose of nifedipine should be considered.
…as ketoconazole, fluconazole, itraconazole, clarithromycin, erythromycin (Azithromycin, although structurally related to the class of macrolide antibiotic is void of clinically relevant CYP3A4 inhibition), grapefruit, nefazodone, fluoxetine, saquinavir, indinavir, nelfinavir, and ritonavir may result in increased exposure to nifedipine when co-administered.
Verapamil: Verapamil, a CYP3A inhibitor, can inhibit the metabolism of nifedipine and increase the exposure to nifedipine during concomitant therapy.
Non-Cardiovascular Drugs Antifungal Drugs Ketoconazole, itraconazole and fluconazole are CYP3A inhibitors and can inhibit the metabolism of nifedipine and increase the exposure to nifedipine during concomitant therapy.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.