Dietary supplements, botanicals, and other alternative medications comprise a market worth over $27 billion annually in the United States. Patients are often unaware of the potency and side effects of these compounds, or the fact that they are not subject to federal regulation. Independent testing of popular vitamins and supplements has often found erroneous listing of ingredients. Even if the ingredients are what the label states, many supplements are known to cause metabolic, hemodynamic and coagulation disturbances which may interfere with anesthetic management in the perioperative period. It is important for anesthesia providers to discuss with their patient what supplements they are using, as well as to familiarize themselves with the potential interactions with their anesthetic plan.
A comprehensive list of herbal and dietary supplements would be nearly impossible; however some of the common ones are reviewed below. A general rule of thumb is to advise stopping all herbal and alternative medicines two weeks prior to surgery; however, in rare instances, it is dangerous to abruptly discontinue an agent which may cause withdrawal symptoms.
The following supplements have been shown to increase the risk of bleeding: 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, additive effect with warfarin), feverfew (inhibits platelet aggregation, additive effects with antiplatelet drugs and warfarin), fish oil (dose-dependent), and vitamin E (can also affect blood pressure).
Agents known to increase clotting risk include coenzyme Q10 (decreases response to warfarin), goldenseal (opposes effects of warfarin and heparin), and St John’s Wort (reduces blood levels of warfarin and MAOI).
Some miscellaneous effects of various supplements include: 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), and valerian (can prolong the effects of some types of anesthesia and abrupt discontinuation can cause benzodiazepine-like withdrawal symptoms).
It is good practice to specifically ask patients if they are using herbal or alternative dietary supplements prior to surgery and to investigate whether serious interactions may occur with the anesthetic plan. The websites www.naturaldatabase.com and www.fda.gov (which reports adverse events) may be useful for looking up unfamiliar agents.