Prescription ·Strong evidence ·Reviewed May 2026
Nifedipine is a dihydropyridine calcium channel blocker used for hypertension and angina (including vasospastic/Prinzmetal angina). The extended-release formulation is preferred; immediate-release nifedipine is no longer recommended for hypertension due to risk of reflex tachycardia and unpredictable blood pressure drops.
The bottom line
Evidence rating strong. Most-documented uses: effective blood pressure reduction, angina relief including prinzmetal (vasospastic) angina, coronary vasodilation. 10 sources indexed (1997–2025), with 5 interaction records on file.
Core mechanism
Potently inhibits L-type calcium channels in vascular smooth muscle, causing arterial vasodilation and reduced peripheral resistance. More selective for vascular smooth muscle than cardiac tissue. Has minimal effects on cardiac conduction. Immediate-release causes rapid vasodilation with reflex sympathetic activation.6,7
Extended-release tablets should be swallowed whole; do not crush or chew; grapefruit juice can significantly increase levels
St. John's Wort induces CYP3A4, which is the primary metabolic pathway for nifedipine. This can dramatically reduce nifedipine levels and blood pressure control.
Recommendation: Avoid St. John's Wort with nifedipine. A documented case showed a patient's BP rose from controlled to 180/100 after starting SJW.
Nifedipine relies on CYP3A4 for clearance, and berberine clinically inhibits CYP3A4 after repeated dosing in humans. Co-administration can raise nifedipine exposure, intensify peripheral vasodilation, and produce hypotension, headache, flushing, or reflex tachycardia. Patients on extended-release formulations or who are volume-depleted are most at risk.
Recommendation: Avoid pairing berberine with nifedipine unless your prescriber agrees. If used together, separate doses by at least 4 hours, check blood pressure and pulse for the first 2 weeks, and stop berberine if you experience flushing, headache, or readings below your usual range.
Resveratrol inhibits CYP3A4 and intestinal P-glycoprotein, and in rats it raised nicardipine AUC 111-126% via both mechanisms. Because nifedipine shares CYP3A4-mediated clearance and dihydropyridine-class side effects, co-administration with high-dose resveratrol supplements is likely to increase plasma nifedipine, producing more flushing, headache, hypotension, and reflex tachycardia.
Recommendation: Avoid high-dose resveratrol supplements while on nifedipine. If used, separate doses by at least 4 hours, monitor blood pressure for 2 weeks after starting, and reduce or stop resveratrol if you develop flushing, headache, or readings below your usual range.
Magnesium is a physiologic calcium-channel modulator that lowers blood pressure by about 2 mmHg systolic at supplemental doses. Combined with nifedipine's strong dihydropyridine vasodilation, the additive effect can produce symptomatic hypotension, headache, flushing, or reflex tachycardia, particularly in pregnant patients receiving magnesium for preeclampsia (a well-known severe interaction).
Recommendation: If you take nifedipine, keep oral magnesium citrate to 200-350 mg/day supplemental elemental magnesium and monitor blood pressure when you start. Reduce or stop magnesium if readings drop below your usual range. Pregnant patients on IV magnesium should be co-managed by their obstetrician and avoid concurrent nifedipine without monitoring.
Aged garlic extract lowers systolic and diastolic blood pressure by about 8 and 5 mmHg in hypertensive patients. Stacked on top of nifedipine's strong dihydropyridine vasodilation, the additive effect can produce dizziness, flushing, headache, or symptomatic hypotension, particularly in patients already at goal blood pressure.
Recommendation: If you take nifedipine, monitor blood pressure for 2-4 weeks after starting garlic extract. Reduce or stop garlic if readings drop below your usual range or you become dizzy, and inform your prescriber so the nifedipine dose can be adjusted if needed.
Numbered references. Citations throughout the page link here.
de Souza ATB, de Lima Machado ML, Sarmento ACA et al.. Magnesium sulfate versus nifedipine for tocolysis: meta-analysis of randomized controlled trials. Women & health. 2025
Li L, Xie W, Xu H et al.. Oral nifedipine versus intravenous labetalol for hypertensive emergencies during pregnancy: a systematic review and meta-analysis. The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians. 2023
Ali AA, Sayed AK, El Sherif L et al.. Systematic review and meta-analysis of randomized controlled trials of atosiban versus nifedipine for inhibition of preterm labor. International journal of gynaecology and obstetrics: the official organ of the International Federation of Gynaecology and Obstetrics. 2019
Stason WB, Schmid CH, Niedzwiecki D et al.. Safety of nifedipine in angina pectoris: a meta-analysis. Hypertension (Dallas, Tex. : 1979). 1999
Stason WB, Schmid CH, Niedzwiecki D et al.. Safety of nifedipine in patients with hypertension: a meta-analysis. Hypertension (Dallas, Tex. : 1979). 1997
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