Supplements and Blood Pressure and Heart Medicines
What NCCIH, the FDA, the NHS and published reviews say about licorice, St. John's wort, hawthorn, green tea and other supplements with blood pressure, digoxin and other heart medicines.
Content last updated . This page has not been medically reviewed.
Heart warning first. NCCIH says licorice contains glycyrrhizin, which can cause serious adverse effects such as irregular heartbeat and cardiac arrest, especially in large amounts or over a long time. It adds that even small amounts have been linked to severe effects in people who consume a lot of salt, people with hypertension, and people with heart or kidney conditions. [1] For chest pain, fainting, severe shortness of breath or a very irregular heartbeat, call 911 (US).
The question
Can an herb or supplement change how a blood pressure or heart medicine works, or strain the heart on its own? Some can. For many others the evidence is old, small or missing. This page sorts what we read and does not suggest using a supplement for a heart condition. Digoxin is one of the "narrow therapeutic range" medicines that NCCIH lists, where a little too much or too little can cause serious reactions, so ask the prescriber or pharmacist before adding anything. [2]What sources say, by supplement
Labels are explained in How interactions work.| Supplement or food | What the source says | Our label |
|---|---|---|
| Licorice root (Glycyrrhiza glabra, glycyrrhizin) | NCCIH: interactions between licorice and corticosteroids have been reported. [1] A toxicology review names hypertension and low potassium (hypokalemia) as the most important side effects. [3] A 2005 review of case reports found hypokalemia after licorice with blood pressure medicines. [4] | Reported; documented caution |
| St. John's wort (Hypericum perforatum) | NCCIH: may weaken digoxin and ivabradine. [5] The NHS says it can affect how digoxin works and lists herbal medicines such as St. John's wort among things that may not mix well with amlodipine. [6][7] | Documented |
| Hawthorn (Crataegus species, leaf and flower extracts studied) | In a trial of 8 healthy volunteers, a hawthorn leaf-with-flower extract (450 mg twice daily for 21 days) did not significantly change digoxin measures. [8] NCCIH notes one study in which a specific hawthorn preparation may have been linked to early heart failure progression, possibly through drug interactions. [9] | Preliminary; results mixed |
| Green tea (Camellia sinensis), high doses or extract | NCCIH: at high doses it reduced blood levels of nadolol, a beta-blocker; extract supplements can raise blood pressure as a side effect. [10] | Preliminary |
| Ginkgo (Ginkgo biloba) | A 2005 review reported high blood pressure when ginkgo was taken with a thiazide diuretic. [4] | Reported |
| "Siberian ginseng" | The 2005 review reported lower digoxin levels with it. [4] The abstract does not say which plant was used; the name may refer to Eleutherococcus senticosus, which is a different species and genus from Asian ginseng (Panax ginseng) in the GBIF plant database. [11] | Reported |
| Grapefruit juice (food) | The FDA names nifedipine and amiodarone as examples of drugs affected. [12] The NHS says not to eat grapefruit with amlodipine or nifedipine. [7][13] See Grapefruit and medicine interactions. | Documented |
| Coenzyme Q10 | The National Cancer Institute says drugs that lower blood pressure may decrease the effects of CoQ10. [14] | Source caution |
For hawthorn, NCCIH also reports that in January 2024 the FDA published a list of products labeled "tejocote root" that actually contained yellow oleander, a toxic plant that can harm the heart, and warned these may cause severe harm or even be fatal. Some people were using these products for weight loss. [9] This is a mislabeling risk, not a hawthorn interaction; see Quality testing and certifications.
The Siberian ginseng and "ginseng" trap
Common names cover different plants. NCCIH's ginseng page is about Asian ginseng. [15] See Ginseng vs Eleuthero for why a result for one does not transfer to the other.Potassium, magnesium and similar minerals
Proper evidence not found. We looked for official statements on potassium or magnesium supplements with blood pressure or heart medicines. NIH's Office of Dietary Supplements pages were blocked from our system (HTTP 403), so we cite nothing from them. The NHS lisinopril page lists other medicines that may not mix well but names no supplements. [16] Ask a pharmacist, and see Potassium.What a reader can do
- Tell the prescriber and pharmacist about every herb, tea, candy and supplement, including licorice in teas or sweets.
- Do not use a supplement in place of a blood pressure or heart medicine. Do not start, stop or change a prescribed medicine on your own.
- Before surgery, tell the surgical and anesthesia team: NCCIH says some supplements may cause serious changes in heart rate or blood pressure. [2] See Supplements before surgery.
- More on conditions: Heart disease, high blood pressure and supplements.
Pregnancy, children and liver disease are not covered by the sources used for this page. See Pregnancy and breastfeeding for official pregnancy statements.
Frequently asked questions
Can licorice affect blood pressure medicines?
NCCIH says even small amounts of glycyrrhizin have been linked to severe effects in people with hypertension or heart conditions. [1] A review reported low potassium after licorice with blood pressure medicines. [4] Ask the prescriber.
Is hawthorn safe with digoxin?
Proper evidence not found for a general answer. One small trial of 8 healthy volunteers found no significant change in digoxin measures, but it studied one extract only. [8] NHS says there is not enough information to say herbal remedies are safe with digoxin. [6]
Does St. John's wort matter for heart medicines?
Yes. NCCIH lists digoxin and ivabradine among medicines it may weaken. [5]
Can green tea affect heart medicines?
At high doses or as an extract, NCCIH says it reduced nadolol levels in a study. [10] NCCIH adds that no safety concerns have been reported for green tea consumed as a beverage by adults, although it contains caffeine. [10]
Which supplement should I use for my blood pressure?
We do not recommend supplements for blood pressure. Ask your clinician. See Heart disease, high blood pressure and supplements.
References
- National Center for Complementary and Integrative Health (NIH, US). Licorice Root: Usefulness and Safety. Last updated April 2025. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Know the Science: Some Medication-Supplement Interactions Can Be Serious. Read 2026-10-23.
- Nazari S, Rameshrad M, Hosseinzadeh H. Toxicological effects of Glycyrrhiza glabra (licorice): a review. Phytother Res. 2017. PubMed 28833680. Abstract read 2026-10-23.
- Izzo AA, Di Carlo G, Borrelli F, Ernst E. Cardiovascular pharmacotherapy and herbal medicines: the risk of drug interaction. Int J Cardiol. 2005. PubMed 15676159. Abstract read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). St. John's Wort: Usefulness and Safety. Last updated May 2025. Read 2026-10-23.
- NHS (England). Taking digoxin with other medicines and herbal supplements. Page last reviewed 22 March 2023. Read 2026-10-23.
- NHS (England). Amlodipine. Page last reviewed 9 June 2026. Read 2026-10-23.
- Tankanow R, Tamer HR, Streetman DS, et al. Interaction study between digoxin and a preparation of hawthorn (Crataegus oxyacantha). J Clin Pharmacol. 2003. PubMed 12817526. Abstract read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Hawthorn: Usefulness and Safety. Last updated April 2025. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Green Tea: Usefulness and Safety. Last updated February 2025. Read 2026-10-23.
- GBIF Secretariat. GBIF Backbone Taxonomy, species-match service queried 2026-10-23 for Hypericum perforatum, Ginkgo biloba, Allium sativum, Glycyrrhiza glabra, Panax ginseng, Crataegus monogyna, Hydrastis canadensis, Camellia sinensis, Eleutherococcus senticosus and Citrus x paradisi.
- U.S. Food and Drug Administration. Grapefruit Juice and Some Drugs Don't Mix. Consumer update, content current as of 2021-07-01. Read in full 2026-10-23.
- NHS (England). Nifedipine. Read 2026-10-23.
- National Cancer Institute (US). Coenzyme Q10 (PDQ), patient version. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH, US). Asian Ginseng: Usefulness and Safety. Last updated February 2025. Read 2026-10-23.
- NHS (England). Lisinopril. Read 2026-10-23.