The Worst Herbs for Heart Health: 14 To Avoid

For people taking prescription drugs for heart problems, some herbs might be best left alone.

Millions of Americans take herbal remedies for ailments ranging from high cholesterol to depression. Although they're widely viewed as safe, some of these products can actually cause serious interactions in people who are also taking prescription drugs for heart problems.

Here, herbal products that heart patients should avoid, using research as well as data from the National Center for Complementary and Integrative Health (NCCIH) to stay safe while taking prescription drugs.

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Garlic is a member of the onion family, available commercially as an oil, extract, or pill (in addition to its natural state). According to the NCCIH, garlic is typically marketed as a way to lower total and LDL (bad) cholesterol as well as blood pressure.

However, the American College of Cardiology stated that "[t]he 4 G's (garlic, gingko, grape seeds, and green tea) should be avoided in persons treated with antiplatelet or anticoagulant medications."

Garlic's blood-thinning properties may increase risk of bleeding associated with aspirin and warfarin—a blood thinning drug commonly prescribed to people with heart-rhythm disorders and who have had heart attacks or heart-valve replacements.

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Saw Palmetto

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The fruit of the palmetto tree (a type of palm tree), saw palmetto is usually available as a capsule, liquid, or tea and is primarily used to fight the urinary problems caused by an enlarged prostate gland. Further, saw palmetto is also used to combat hair loss, chronic pelvic pain, and decreased sex drive, according to the NCCIH.

Like garlic, saw palmetto also increases the risk of bleeding associated with warfarin and must be used with caution alongside NSAIDs or during surgical procedures, per a January 2019 EPMA Journal study.

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The extract of ginkgo leaves is mainly used to improve memory and prevent dementia (including Alzheimer's disease). Per the NCCIH, it has also been used to treat asthma, ringing in the ears, sexual dysfunction, and leg pain caused by poor circulation.

According to a March 2017 study in the Journal of the American College of Cardiology, gingko also increases the risk of bleeding associated with aspirin and warfarin.

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St. John's Wort

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St. John's wort is a yellow-flowered plant, Hypericum perforatum, that is sold as a capsule, tea, or liquid extract. The plant is primarily used to treat depression and anxiety and as a sedative in sleep disorders.

According to the American Heart Association (AHA), St. John's wart can "reduce the concentration of medications in the blood." In other words, it can make medications for heart failure (e.g., Lanoxin) or lowering cholesterol (e.g., Mevacor and Altocor) less effective.

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Green Tea


The purposes for consuming green tea (from leaves of the Camellia sinensis plant) as a beverage, capsule, or extract include losing weight, improving mental alertness, lowering cholesterol, and preventing cancer.

Green tea may interfere with adenosine, a medication for irregular heart rhythms. This type of tea also contains vitamin K, "which can reduce the effectiveness of anticoagulant medications, such as warfarin" per the March 2017 Journal of the American College of Cardiology study. Further, the caffeine in green tea also could interfere with beta-blockers.

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The ground, dried leaves of alfalfa are ground up and sold as capsules. People often take the capsules in order to lower total and LDL cholesterol and to reduce the plaque buildup as a result of atherosclerosis.

Like green tea, alfalfa contains vitamin K. This means that it too can increase risk of bleeding since it "might decrease the effects of warfarin," according to MedlinePlus.

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Ginger has been used for centuries to treat various stomach ailments (such as nausea, diarrhea, and stomachache). It is also used to treat joint and muscle pain.

Ginger might interfere with blood clotting or increased bleeding for those taking warfarin, although more research is needed on this, according to the January 2019 EPMA Journal study. To be safe, speak to your healthcare provider if you're taking ginger supplements as well as warfarin or aspirin.

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Bilberry is used to treat problems associated with poor circulation, most notably varicose veins and venous insufficiency, in addition to diarrhea, skin problems, eyestrain, and menstrual cramps.

Bilberry may improve blood circulation. However, speak to your healthcare provider before taking it along with blood thinners as—per the National Library of Medicine (NLM)—it could lead to excessive bleeding.

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An herb native to Asia, ginseng has been used in traditional medicine for centuries and is now sold as a capsule. Ginseng is often used boost energy, stamina, and the immune system as well as to lower LDL cholesterol and blood pressure.

When overused, ginseng can diminish the effect of warfarin, according the AHA—while also enhancing the bleeding effects of with aspirin, NSAIDs, and heparin. It can also interact with other heart medications, such as calcium channel blockers.

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Grapefruit Juice

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To speed up weight loss and improve heart health, people might turn to grapefruit juice. However, the FDA has stated that grapefruit juice interferes with an enzyme that is essential for properly absorbing medications. This includes cholesterol-lowering statins such as Lipitor and Zocor or high blood pressure medications, which intensifies the effect of those drugs.

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Aloe Vera


In addition to its familiar use as a lotion and salve, aloe is taken orally to treat serious health conditions including arthritis, epilepsy, diabetes, and asthma.

Aloe vera can cause a drop in the blood's potassium level, which in turn can lead to heart rhythm problems. The potassium level drop could also result in complications for heart patients taking the drug digoxin for arrhythmia or congestive heart failure.

Further, aloe has the "potential to increase bleeding if antiplatelet analgesic drugs, such as aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs), are used simultaneously" per the EPMA Journal study published in January 2019.

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Black Cohosh

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Black cohosh, sold as a capsule, is mainly used to assuage the symptoms of menopause (hot flashes, vaginal dryness, night sweats), but it has also been used to treat joint and muscle pain.

Ultimately, black cohosh may interfere with certain prescription medications, including cholesterol-lowering statins, according to the NCCIH.

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The fruit of the hawthorn shrub has been used to treat the symptoms of heart disease, while the leaf and flower are also used to treat heart failure.

Hawthorn may interact negatively with prescription heart-failure medications. The NCCIH recommended talking to your healthcare provider about using hawthorn before incorporating it into your diet.

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Licorice Root

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The dried extract of the root of the licorice plant is typically sold as a capsule. Licorice root is used to treat ulcers and other stomach ailments, bronchitis and sore throat, and some viral infections.

The NCCIH has said that "The effects of licorice on potassium and blood pressure are a particular concern for people with hypertension (high blood pressure) or heart or kidney disease." Licorice root could interfere with ace-inhibitors or diuretics that regulate blood pressure.

At any rate, for any herbs or herbal supplements you want to add to your diet, it's always best to consult your healthcare provider for guidance.

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