What is the dermatologic preoperative evaluation and management of garlic?

Updated: Mar 16, 2020
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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Of the 38% of Americans using herbal medications in the past 2 years, 27% of them were garlic users. Garlic has the potential to modify the risk of atherosclerosis by reducing blood pressure and thrombus formation and by lowering serum lipid and cholesterol levels. These effects are primarily attributed to the sulfur-containing compounds, particularly allicin and its transformation products.

Garlic inhibits platelet aggregation in a dose-dependent fashion. The effect of one of its constituents, ajoene, appears to be irreversible and may potentiate the effect of other platelet inhibitors, such as prostacyclin, forskolin, indomethacin, and dipyridamole. The platelet-altering effects of garlic have not been consistently demonstrated in volunteers taking high doses. However, one case report documented in the literature is that of an octogenarian who developed a spontaneous epidural hematoma attributed to the heavy use of garlic. In addition to concerns about bleeding, garlic has the potential to lower blood pressure. In laboratory animals, allicin decreased systemic and pulmonary vascular resistance and lowered blood pressure. In humans, the antihypertensive effect of garlic is marginal. Garlic results in the potential adverse effects of dizziness, headache, irritability, nausea, vomiting, anorexia, and irritation of oral mucosa.

Although the pharmacokinetic data of the constituents of garlic are insufficient, the potential for irreversible inhibition of platelet function may warrant patients to discontinue the use of garlic at least 7 days prior to surgery, especially if postoperative bleeding is a particular concern or if other platelet inhibitors have been given.

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