Supplements, foods, or drinks to avoid when taking Plavix

Amy Malec
Tod Cooperman, M.D.

Written by Amy Malec — Medically reviewed and edited by Tod Cooperman, M.D.Last Updated: 01/19/2023 Initially Posted: 11/14/2020


Answer:

Yes, certain supplements may increase or decrease the effectiveness of clopidogrel (Plavix). This can increase the risk of bleeding or, conversely, increase the risk of blood clots. Clopidogrel is a “prodrug,” meaning it must be broken down by the body to become active. Two liver enzymes, CYP3A4 and CYP2C19, are responsible for this. Consequently, supplements that inhibit these enzymes may reduce the effectiveness of clopidogrel, while supplements that that induce these enzymes may increase the activity of clopidogrel.

Supplements and beverages that may reduce the effects of clopidogrel
Cannabidiol (CBD) can inhibit CYP2C19 when taken in large doses (usually several hundred milligrams). Furthermore, CBD is broken down in the body by CYP2C19. By competing for and inhibiting this enzyme, CBD might reduce the effects of clopidogrel. Although this interaction has not been proven, CBD has been shown to reduce the breakdown of other drugs metabolized by CYP2C19 (U.S Department of HealthIffland, Cannabis Cannabinoid Res 2017Klotz, Epilepsia 2019).

Kava has been shown to inhibit CYP2C19 in animal research (Mathews, Drug Metab Dispos 2005), and ginger extract and chemicals found in gardenia and holy basil have been shown to inhibit CYP2C19 in cell culture studies (Kim, Die Pharmazie 2012Gao, Fitoterapia 2014Kim, Life Sci 2004). Potentially, these supplements might decrease the blood-thinning effects of clopidogrel, although these interactions have not been proven.

Grapefruit juice, a potent CYP3A4 inhibitor, can also inhibit CYP2C19. One study showed that people who drank 200 mL of grapefruit juice three times per day for three days before taking a single 600-mg dose of clopidogrel experienced 13% lower blood levels of the active form of clopidogrel compared to those who drank water (Holmberg, Clin Pharmacol Ther 2014). This could potentially reduce the blood-thinning effects of clopidogrel.

Supplements and foods that may increase the effects of clopidogrel
On the other hand, some supplements may induce CYP2C19. Potentially, this may lead to excessive blood levels of clopidogrel, which might increase the risk of bleeding. Supplements that induce CYP2C19 include St. John’s wortGinkgo biloba, and others (Wang, Clin Pharmacol Ther 2004Wang, Clin Pharmacol Ther 2004Yin, Pharmacogenetics 2004).

In addition, several supplements may, themselves, have blood-thinning effects that could potentially increase the risk of bleeding when taken with blood thinning medications, although this interaction has not been proven. To be safe, consult your physician before using the following in combination with a blood thinner: Fish oilashwagandhachondroitincurcumin and turmericgarlicmelatoninnattokinaseresveratrol, and NAC. [Note: In addition to their effects on CYP2C19, both ginger and Ginkgo biloba may also have additive blood-thinning effects.]

Consumption of cocoa or dark chocolate (65% cocoa solids) may enhance the antiplatelet effects of clopidogrel, according to one small study in people with coronary artery disease who were taking clopidogrel and aspirin.

Unlike the blood thinner warfarin, which can be affected by vitamin K, clopidogrel is not thought to be affected by vitamin K intake.