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Drugs, Devices & Supplements

Herbal Supplement Safety

Although herbs and herbal supplements seem harmless, they can be potentially dangerous, especially to anyone taking medication for a heart problem. Unlike conventional medications, most herbs have not been tested by the Food and Drug Administration (FDA) for safety and effectiveness. Serious, even fatal, interactions have been reported between heart medications and some herbal supplements.


If you take aspirin, digoxin, diuretics, hypoglycemics, nonsteroidal anti-inflammatory drugs, spironolactone or warfarin, DO NOT use herbal supplements without first checking with your doctor.

Name of Remedy Uses Risks
Ephedra (Ephedra sinica, also called Ma-Huang) To treat coughs and obesity Dangerous and life-threatening increases in heart rate and blood pressure. Has potentially fatal interactions with many heart medications.
Garlic (Allium sativum) To lower cholesterol; to prevent and treat colds and certain infections Excessive bleeding in people taking anticoagulant medications such as warfarin (Coumadin).
Ginkgo (Ginkgo biloba) To improve mental functioning, circulation; to prevent altitude sickness Increases the risk of excess bleeding when taken with anticoagulant drugs. Interferes with action of diuretics.
Goldenseal (Hydrastis canadensis) To treat constipation; acts as an anti-inflammatory Interferes with blood-thinning drugs and can cause high blood pressure, hallucinations and delirium.
Hawthorn (Crataegus species) To treat congestive heart failure and high blood pressure Should not be taken by anyone taking heart medications.
Licorice root (Glycyrrhiza glabra) To treat coughs, cirrhosis and stomach ulcers Should not be used by anyone with a heart condition or by anyone taking heart medications. Raises blood pressure.

Many of the drug interactions occur because herbs contain natural compounds called coumarins that act like anticoagulants. Additional anticoagulant properties in some herbal supplements interfere with the workings of the prescription drugs.

High levels of vitamin K are also a problem, as vitamin K interferes with warfarin. Large amounts of food high inVitamin K (green, leafy vegetables; broccoli, cabbage, asparagus, brussels sprout, okra, and frozen peas) may affect the way warfarin works. It is important to keep your diet consistent. Avoiding foods containing Vitamin K is not necessary, but talk to your health care provider if you plan to make major changes in your diet.

Other supplements known to cause heart problems, whether or not a person is also taking heart medications:

  • Aloe — used internally to relieve constipation and externally to soothe irritated skin and burns. When taken internally, aloe can cause abnormal heart rhythms in pregnant women and in children.
  • Arnica (Arnica montana) — applied externally to reduce pain from bruising, aches, and sprains, and to relieve constipation. Arnica is potentially toxic to the heart and can raise blood pressure if taken internally.
  • Black cohosh (Cimicifuga racemosa) — used to relieve menopausal symptoms. Can cause lowered blood pressure when taken at high doses.
  • Beta carotene — antioxidant thought to fight free radicals (substances that harm the body when left unchecked). Using vitamin supplements that contain beta carotene should be actively discouraged because of an increased risk of death.
  • CoQ10 (Coenzyme Q10, ubiquinone, ubidecarenone) — used to increase energy and to treat heart failure. Does not improve heart function. CoQ10 is highly concentrated in heart muscle cells due to the high energy requirements of this cell type.
  • Feverfew (Tanacetum parthenium) — believed to prevent and treat migraines, arthritis, and allergies. Feverfew can interfere with blood clotting when taken internally.
  • Ginger — thought to relieve nausea and motion sickness, lower blood cholesterol, decrease platelet aggregation, and act as a digestive aid and antioxidant. Ginger can interfere with blood clotting.
  • Ginseng (Panax ginseng) — thought to slow aging, increase mental and physical capacity, increase sexual performance, and boost immunity. It should not be taken by people with hypertension.
  • Nettle (Urtica dioica) — thought to fight urinary tract infections, kidney and bladder stones, and rheumatism. It is used externally to control dandruff. Nettle should not be taken by people with fluid retention caused by reduced heart or kidney function.

The FDA's medical products reporting program, tracks reports of serious adverse events of products. MedWatch can be contacted at 888.723.3366 ( You can also call the FDA consumer hotline at 888.Info.FDA (888.463.6332).


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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 9/1/2010...#12885