RESEARCH STARTER

Calcium channel blockers (drug interactions)

Calcium channel blockers (CCBs) are a class of medications primarily used to treat conditions such as hypertension, angina, and certain heart arrhythmias. While effective in managing these heart-related issues, CCBs can interact with various substances, potentially altering their effectiveness. Key interactions involve calcium and vitamin D supplements, which may reduce the action of CCBs. Additionally, Ginkgo biloba may hasten the metabolism of these drugs, leading to diminished therapeutic effects. The citrus bioflavonoid naringin is known to increase the blood levels of CCBs, possibly necessitating dosage adjustments. Other herbs and supplements, including St. John's wort and hawthorn, can also affect how CCBs work, with some potentially lowering blood pressure to unsafe levels. It is crucial for individuals taking CCBs to be aware of possible interactions with other prescription medications, such as statins and antifungals, as well as common dietary components like grapefruit juice. Consulting with healthcare providers about these interactions is vital for safe and effective treatment.

Full Article

DEFINITION: Medications used to treat hypertension, angina, heart arrhythmia, and other heart-related conditions.

  • INTERACTIONS: Calcium, Ginkgo biloba, naringin (a citrus bioflavonoid), vitamin D, and many others
  • DRUGS IN THIS FAMILY: Amlodipine (Norvasc), diltiazem (Cardizem, Cardizem CD, Cardizem SR, Dilacor XR, Tiamate, Tiazac), felodipine (Plendil), isradipine (DynaCirc, DynaCirc CR), nicardipine hydrochloride (Cardene, Cardene SR), nifedipine (Procardia, Procardia XL, Adalat, Adalat CC), nimodipine (Nimotop), nisoldipine (Sular), verapamil (Calan, Calan SR, Covera-HS, Isoptin, Isoptin SR, Verelan)

Calcium and Vitamin D

Effect: Possible Decreased Action of Drug

Taking calcium and vitamin D supplements might interfere with some of the effects of calcium channel blockers.

Ginkgo biloba

Effect: Possible Decreased Action of Drug

According to a study in rats, ginkgo extract may cause the body to metabolize some calcium channel blockers more rapidly, thereby decreasing their effects.

Naringin (Citrus Bioflavonoid)

Effect: May Necessitate Reduction in Drug Dosage

Some evidence suggests that the bioflavonoid naringin may interact with medications in the calcium channel blocker family, increasing the drug's blood levels. This may necessitate a reduction in drug dosage.

Several other herbs and natural supplements may interfere with calcium channel blockers. St. John’s wort may decrease their effectiveness. When taken with calcium channel blockers, hawthorn may lower blood pressure to dangerous levels. Ginseng, magnesium, and goldenseal may interact adversely with calcium channel blockers. It is also important to remember that other prescription medications may also interact with calcium channel blockers. Patients taking statins, antifungals, antibiotics, and antiarrhythmic medications should talk with their healthcare provider. Finally, grapefruit juice can also interfere with the breakdown of calcium channel blockers in the body. 


Bibliography

"Calcium Channel Blockers for High Blood Pressure: Types, Uses, Effects." WebMD, 18 Dec. 2023, www.webmd.com/hypertension-high-blood-pressure/treatment-calcium-channel. Accessed 17 Dec. 2025.

Guadagnino, V., et al. "Treatment of Severe Left Ventricular Dysfunction with Calcium Chloride in Patients Receiving Verapamil." Journal of Clinical Pharmacology, vol. 27, 1987, pp. 407-9.

Horowitz, B. Zane. "Calcium Channel Blocker Toxicity." Medscape, 4 Apr. 2023, emedicine.medscape.com/article/2184611-overview. Accessed 17 Dec. 2025.

Kuhn, M., and D. L. Schriger. "Low-Dose Calcium Pretreatment to Prevent Verapamil-Induced Hypotension." American Heart Journal, vol. 124, 1992, pp. 231-2.

Luscher, T. F., et al. "Calcium Gluconate in Severe Verapamil Intoxication." New England Journal of Medicine, vol. 330, 1994, pp. 718-20.

Margolis, K. L., et al. "Effect of Calcium and Vitamin D Supplementation on Blood Pressure." Hypertension, vol. 52, 2008, pp. 847-55.

McKeever, Rita G., et al. "Calcium Channel Blockers - StatPearls." NCBI, 22 Feb. 2024, www.ncbi.nlm.nih.gov/books/NBK482473. Accessed 17 Dec. 2025.

Full Article

DEFINITION: Medications used to treat hypertension, angina, heart arrhythmia, and other heart-related conditions.

  • INTERACTIONS: Calcium, Ginkgo biloba, naringin (a citrus bioflavonoid), vitamin D, and many others
  • DRUGS IN THIS FAMILY: Amlodipine (Norvasc), diltiazem (Cardizem, Cardizem CD, Cardizem SR, Dilacor XR, Tiamate, Tiazac), felodipine (Plendil), isradipine (DynaCirc, DynaCirc CR), nicardipine hydrochloride (Cardene, Cardene SR), nifedipine (Procardia, Procardia XL, Adalat, Adalat CC), nimodipine (Nimotop), nisoldipine (Sular), verapamil (Calan, Calan SR, Covera-HS, Isoptin, Isoptin SR, Verelan)

Calcium and Vitamin D

Effect: Possible Decreased Action of Drug

Taking calcium and vitamin D supplements might interfere with some of the effects of calcium channel blockers.

Ginkgo biloba

Effect: Possible Decreased Action of Drug

According to a study in rats, ginkgo extract may cause the body to metabolize some calcium channel blockers more rapidly, thereby decreasing their effects.

Naringin (Citrus Bioflavonoid)

Effect: May Necessitate Reduction in Drug Dosage

Some evidence suggests that the bioflavonoid naringin may interact with medications in the calcium channel blocker family, increasing the drug's blood levels. This may necessitate a reduction in drug dosage.

Several other herbs and natural supplements may interfere with calcium channel blockers. St. John’s wort may decrease their effectiveness. When taken with calcium channel blockers, hawthorn may lower blood pressure to dangerous levels. Ginseng, magnesium, and goldenseal may interact adversely with calcium channel blockers. It is also important to remember that other prescription medications may also interact with calcium channel blockers. Patients taking statins, antifungals, antibiotics, and antiarrhythmic medications should talk with their healthcare provider. Finally, grapefruit juice can also interfere with the breakdown of calcium channel blockers in the body. 


Bibliography

"Calcium Channel Blockers for High Blood Pressure: Types, Uses, Effects." WebMD, 18 Dec. 2023, www.webmd.com/hypertension-high-blood-pressure/treatment-calcium-channel. Accessed 17 Dec. 2025.

Guadagnino, V., et al. "Treatment of Severe Left Ventricular Dysfunction with Calcium Chloride in Patients Receiving Verapamil." Journal of Clinical Pharmacology, vol. 27, 1987, pp. 407-9.

Horowitz, B. Zane. "Calcium Channel Blocker Toxicity." Medscape, 4 Apr. 2023, emedicine.medscape.com/article/2184611-overview. Accessed 17 Dec. 2025.

Kuhn, M., and D. L. Schriger. "Low-Dose Calcium Pretreatment to Prevent Verapamil-Induced Hypotension." American Heart Journal, vol. 124, 1992, pp. 231-2.

Luscher, T. F., et al. "Calcium Gluconate in Severe Verapamil Intoxication." New England Journal of Medicine, vol. 330, 1994, pp. 718-20.

Margolis, K. L., et al. "Effect of Calcium and Vitamin D Supplementation on Blood Pressure." Hypertension, vol. 52, 2008, pp. 847-55.

McKeever, Rita G., et al. "Calcium Channel Blockers - StatPearls." NCBI, 22 Feb. 2024, www.ncbi.nlm.nih.gov/books/NBK482473. Accessed 17 Dec. 2025.

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