Herbal Supplements: Implications for Anesthesia

Humans have used herbs and plants for medicinal purposes since ancient times.¹ The oldest written evidence of medicinal plants’ usage for drug preparation is on a 5000-year-old Sumerian clay slab from Nagpur.¹ It includes 12 recipes for drug preparation with over 250 various plants, including poppy, henbane, and mandrake.¹ These plants contain pharmacologically active components that can treat illness.¹ Today, herbal medicines’ therapeutic potential should not be dismissed, given the long history of their successful use.² Herbal products may also interfere with other contemporary medicines, so medical providers must be aware of their potential effects and mechanisms of action.² Anesthesia providers in particular should be aware of commonly used herbal supplements and their functions, as well as their potential to affect anesthetic drugs.

Herbal products, also known as dietary supplements, alternative therapies, complementary medicine and homeopathic or holistic health care, are common in many societies.³ According to the World Health Organization (WHO), up to 80 percent of the world’s population still depends on herbal medicines.⁴ Patient surveys have reported that 12 percent of Americans, 12 percent of Australians, and 4.8 percent of patients in the UK use herbal remedies.⁴ Commonly used compounds include feverfew, garlic, ginseng, ginkgo, St. John’s wort, hoodia, kava, valerian and echinacea.^3,5 Because the United States Food and Drug Administration (FDA) considers these pharmacologically active agents as foods or supplements, they are not subject to standard drug regulations.² There are limited instructions on proper use, dosage requirements, possible side effects, toxicity and drug interactions.³ Also, a lack of pharmacokinetic and pharmacodynamic data on herbal products makes it difficult to predict a patient’s reaction to the product or know if the product has any therapeutic value.⁴ Due to unstandardized dosage policies and unclear pharmacological effects, herbal supplements can be harmful to patients whether or not they are taking other medications.

Because of the possible interference with anesthetic medications, the American Society of Anesthesiologists recommends that patients discontinue the use of herbal supplements two to three weeks before surgery.⁴ However, patients are often unaware of this recommendation or in need of emergency surgery, in which case preoperative preparation time is limited.⁴ According to a study by Levy et al., 44 percent of patients hospitalized for surgery reported dietary and herbal supplement use, with 16.5 percent using substances that could potentially interact with anesthesia.⁶ In a separate study, Kaye et al. found that among 1,017 patients surveyed before outpatient anesthetic administration, 482 were using at least one herbal supplement.⁷ Despite some of the benefits of these supplements, they can negatively impact postoperative analgesia, bleeding and level of sedation.² Wong et al.’s review thoroughly describes the medicinal uses, pharmacological effects and potential anesthetic interactions of several common herbal supplements.⁴ Garlic, ginger, gingko and ginseng contribute to intraoperative risk of bleeding; kava, St. John’s wort and valerian have sedative effects and may reduce anesthetic requirements; ephedra causes sympathetic nervous system issues and arrhythmia; and echinacea can cause liver failure when combined with hepatotoxic drugs.⁴ Despite the potential perioperative dangers of these drugs on their own or in combination with anesthetic agents,³ documentation and identification of herbal remedies in medical records remain subpar. For example, in Levy et al.’s study, supplement use was only documented in 11 percent of the medical files of patients who used them.⁶ It is the anesthesia provider’s duty to ask patients open-ended questions about their herbal supplement use during the preoperative assessment.⁸ Adequate reporting of patient use and proper understanding of herbal supplement pharmacology are key to an anesthesia provider’s practice.⁸

Medicinal herbs have been used for thousands of years, and many herbs contribute to the pharmacological effects of modern-day medications. Despite their widespread use, herbal supplements are not heavily regulated and may pose dangers to patients, whether or not they use other medicines. Anesthesia providers should consider the pharmacology and possible perioperative effects of these supplements. Ideally, the anesthesia provider should ensure the patient’s discontinuation of such products well before surgery.⁴ Future research should investigate the possible uses of herbal supplements for anesthesia and analgesia to aim for a more symbiotic relationship between herbal supplements and allopathic medicine.  

1.         Petrovska BB. Historical review of medicinal plants’ usage. Pharmacognosy Reviews. 2012;6(11):1–5.

2.         Abe A, Kaye AD, Gritsenko K, Urman RD, Kaye AM. Perioperative analgesia and the effects of dietary supplements. Best Practice & Research Clinical Anaesthesiology. 2014;28(2):183–189.

3.         American Society of Nurse Anesthetists. Herbal Products and Your Anesthesia. Patients 2019; https://www.aana.com/patients/herbal-products-and-your-anesthesia.

4.         Wong A, Townley SA. Herbal medicines and anaesthesia. Continuing Education in Anaesthesia Critical Care & Pain. 2010;11(1):14–17.

5.         Skinner CM, Rangasami J. Preoperative use of herbal medicines: A patient survey. BJA: British Journal of Anaesthesia. 2002;89(5):792–795.

6.         Levy I, Attias S, Ben-Arye E, et al. Perioperative Risks of Dietary and Herbal Supplements. World Journal of Surgery. 2017;41(4):927–934.

7.         Kaye AD, Clarke RC, Sabar R, et al. Herbal medicines: Current trends in anesthesiology practice—a hospital survey. Journal of Clinical Anesthesia. 2000;12(6):468–471.

8.         Lyons TR. Herbal medicines and possible anesthesia interactions. AANA Journal. 2002;70(1):47–51.