Prescription ·Strong evidence ·Reviewed May 2026
Felodipine is a long-acting dihydropyridine calcium channel blocker used primarily to treat hypertension, alone or in combination with other antihypertensive agents. It is highly selective for vascular smooth muscle over cardiac muscle, producing peripheral arteriolar vasodilation with little direct effect on cardiac contractility or conduction. It is formulated as an extended-release tablet to provide once-daily blood pressure control.
The bottom line
Evidence rating strong. Most-documented uses: hypertension, stable angina pectoris (in some regions). 3 sources indexed (1991–2012), with 7 interaction records on file.
Core mechanism
Felodipine binds to L-type voltage-gated calcium channels in vascular smooth muscle and inhibits the influx of extracellular calcium during membrane depolarization. By reducing intracellular calcium availability, it decreases the contraction of arteriolar smooth muscle, leading to vasodilation, reduced peripheral vascular resistance, and lowered arterial blood pressure. Its high vascular selectivity means therapeutic doses cause minimal negative inotropic or chronotropic effects, and reflex tachycardia from vasodilation is generally modest. Felodipine is extensively metabolized by hepatic CYP3A4, so inhibitors of this enzyme such as grapefruit juice can markedly increase its plasma concentrations and effect.1,2
Should be taken consistently either without food or with a light meal; a high-fat meal can substantially increase peak concentration. Avoid grapefruit and grapefruit juice, which inhibit CYP3A4 and markedly raise felodipine levels, increasing risk of hypotension and edema.1,2
St. John's Wort can induce drug-metabolizing enzymes and transporters and may lower Felodipine exposure or undermine therapy.
Recommendation: Avoid starting or stopping St. John's Wort without prescriber review while taking Felodipine.
Magnesium Glycinate may add to the blood-pressure-lowering effect of Felodipine.
Recommendation: Monitor blood pressure and dizziness, especially during dose changes; stop the supplement and seek advice if syncope, falls, or symptomatic hypotension occurs.
L-Citrulline may add to the blood-pressure-lowering effect of Felodipine.
Recommendation: Monitor blood pressure and dizziness, especially during dose changes; stop the supplement and seek advice if syncope, falls, or symptomatic hypotension occurs.
St. John's Wort is a potent inducer of intestinal and hepatic CYP3A4, the primary enzyme that metabolizes felodipine, which already has very low oral bioavailability (about 15 percent) because of extensive first-pass metabolism. Concomitant use markedly lowers felodipine plasma concentrations and can result in loss of antihypertensive control.
Recommendation: Avoid combining St. John's Wort with felodipine. If a patient is already taking St. John's Wort, do not start it during felodipine therapy, and if it must be stopped, monitor blood pressure closely for several weeks because enzyme induction reverses slowly. Discuss alternatives with the prescriber.
Green tea catechins can inhibit intestinal organic anion transporting polypeptides and may modestly affect CYP3A4 and P-glycoprotein, with the potential to alter felodipine absorption. Concentrated green tea extracts in supplement form deliver far higher catechin loads than brewed tea and carry an established risk of hepatotoxicity that can complicate the picture.
Recommendation: Be cautious with high-dose green tea extract supplements while on felodipine. Separate ingestion from the dose where possible, watch for changes in blood pressure or unexpected adverse effects, and report signs of liver injury such as dark urine, jaundice, or abdominal pain.
Quercetin inhibits CYP3A4 and P-glycoprotein in laboratory and some clinical studies. Because felodipine is a sensitive CYP3A4 substrate with low and variable oral bioavailability, high-dose quercetin supplements could raise felodipine concentrations and increase the risk of hypotension, flushing, headache, and peripheral edema.
Recommendation: Avoid high-dose quercetin supplements with felodipine unless cleared by the prescriber. If used, monitor for excessive blood-pressure lowering and dihydropyridine side effects, and keep the dose modest.
Garlic supplements have modest blood-pressure-lowering activity and can add to the antihypertensive effect of felodipine. The combined effect is usually small but may contribute to dizziness or symptomatic hypotension in sensitive individuals.
Recommendation: Garlic supplements are generally acceptable with felodipine, but monitor blood pressure when starting or changing the dose and watch for lightheadedness, particularly in older adults or those on multiple antihypertensives.
Numbered references. Citations throughout the page link here.
Felodipine exhibits high selectivity for vascular smooth muscle, effectively lowering blood pressure with little negative inotropic activity at therapeutic doses.
Recommended starting dose is 5 mg once daily, usual range 2.5 to 10 mg, with peripheral edema being the most common dose-related adverse effect.
Grapefruit juice substantially raised felodipine area-under-curve and peak plasma concentration, with augmented blood pressure lowering and reflex tachycardia.
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