February 1, 2014 Volume 78, Number 2
ACE Question

Which of the following is MOST likely to occur in a patient consuming large quantities of garlic or taking herbal preparations of garlic?

(A) Increased heart rate

(B) Inhibition of platelet aggregation

(C) Hypoglycemia

(D) Sedation

In 2001, garlic was noted to account for slightly more than 6 percent of all sales of herbal medications in the United States. It is used to modify the risk of atherosclerosis; systematic reviews report that it is effective in lowering serum cholesterol by 4 percent to 6 percent. Garlic produces a dose-dependent inhibition of platelet function. One of the components of garlic has been reported to have an irreversible effect on platelet function and to potentiate the effects of other drugs that inhibit platelet activity. One case report attributes a spontaneous epidural hematoma to prolonged garlic use. Because of the irreversible nature of the platelet inhibition, it is generally recommended that garlic administration be discontinued seven days or more prior to elective surgery. Garlic is not reported to produce tachycardia, hypoglycemia, or sedation.

Despite the fact that the U.S. Food and Drug Administration banned the sale of ephedra in 2004, it is reportedly still widely available over the Internet. Ephedra (ma huang in Chinese medicine) is used as a stimulant (to increase weight loss and energy) and a bronchodilator (for asthma and bronchitis). Blood pressure and heart rate are increased by ephedra in a dose-dependent manner. There have been well over 1,000 adverse events (including fatal cardiac complications and stroke) reported in conjunction with the use of ephedra. Because ephedra has an elimination half-life of approximately five hours, it is generally recommended that its use be discontinued 24 hours prior to elective surgery.

Ginseng is taken to improve physical performance or protect the body against stress. Ginseng has been shown to decrease postprandial glucose levels in patients with diabetes and may produce hypoglycemia during preoperative fasting. Ginseng is also reported to have a potentially irreversible effect on platelet function. Although the elimination half-life of ginseng is approximately seven hours, the irreversible effect on platelet function suggests that its use should be discontinued seven days prior to elective surgery.

Kava, widely used as an anxiolytic or sedative, produces dose-dependent depression of central nervous system activity. Acute use is associated with an increase in the sedative effects of anesthetic agents, while longstanding use has been reported to increase anesthetic requirements. Kava is reported to have an abuse potential, but whether this can result in true addiction or withdrawal has not been determined.


• Ang-Lee M, Yuan CS, Moss J. Complementary and alternative therapies. In: Miller RD, ed. Miller’s Anesthesia. 7th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2010:959–961.

• Bent S, Ko R. Commonly used herbal medicines in the United States: a review. Am J Med. 2004;116(7):478–485.

• Kaye AD, Kucera I, Sabar R. Perioperative anesthesia clinical considerations of alternative medicines. Anesthesiol Clin North America. 2004;22(1):125–139.

Answer: B

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