Americans spend over $27 billion yearly on herbal supplements, botanicals, and other alternative medicines. Many are unaware of the potency and potential side effects of these agents, which are not subject to federal regulation. Some supplements may cause electrolyte disturbances, anticoagulation effects, interactions with other medications, or interaction with anesthetic agents. Moreover, not only do patients often not disclose the supplements they are taking to their anesthesia providers, providers may be unaware of the implications of these herbal supplements on their anesthetic.
A brief review of some common herbs and supplements that may have anesthetic implications is presented below. However, the list of available supplements patients take is so vast, it is difficult to cover them all. The anesthesia provider should address with the patient if she/he is using herbal supplements, and to make an effort to determine if any potentially serious side effects could arise from their continued use perioperatively. While it is generally safe to advise patients to discontinue herbals one or two weeks prior to surgery, it may be dangerous to abruptly stop some agents. These may require tapering or continuation during the perioperative period.
Supplements known to increase the risk of bleeding include garlic (inhibits platelet aggregation), ginkgo (inhibits platelet activating factor), ginseng (inhibits platelet aggregation; also decreases blood glucose), saw palmetto (unknown mechanism), black cohosh (NSAID-like properties), chamomile (contains phytocoumarins which have an additive effect with warfarin), feverfew (inhibits platelet aggregation and has additive effects with antiplatelet drugs and warfarin), fish oil (dose-dependent), and vitamin E (can also affect blood pressure).
Herbals that increase clotting risk include coenzyme Q10 (through a decreased response to warfarin), goldenseal (opposes effects of warfarin and heparin), and St John’s Wort (reduces blood levels of warfarin).
Other supplements also have different effects. Ephedra (Ma-Huang) may interact with blood pressure medications and cause tachycardia and hypertension. Kava can increase the effect of anesthesia and has been implicated in liver dysfunction in rare cases. Valerian can prolong the effects of some types of anesthesia. Abrupt discontinuation of this agent may cause benzodiazepine-like withdrawal symptoms.
Further resources for information on supplements include www.naturaldatabase.com and www.fda.gov (which reports adverse events). While sometimes time-consuming (some patients may be taking ten or more supplements), it is good to at the very least, to have an open discussion with patients regarding the use and potential side effects of the medications they are taking, whether prescription or alternative.