A 2024 review in the Journal of Clinical Anesthesia catalogues the perioperative risks of 33 herbal supplements, finding plausible bleeding, cardiovascular, and sedation interactions with anesthetic agents. Up to 70% of surgical patients never tell their doctors about herbal use, and most of the evidence underpinning specific interaction warnings remains preliminary rather than trial-proven.

Herbal supplement retail sales in the United States surpassed $13 billion in 2021, and surgical patients are among the heaviest users. Despite this, between 50% and 70% of patients undergoing surgery never disclose their herbal use to their physicians or anesthesiologists. This creates a largely invisible layer of pharmacologic risk during procedures where even modest bleeding, sedation, or cardiovascular effects can have serious consequences. Clinicians who prescribe or encounter supplements in any context need to understand what is known, and what remains uncertain, about these perioperative interactions.

The growing prevalence of herbal supplement use among surgical patients collides with a regulatory landscape that, since the passage of the Dietary Supplement Health and Education Act (DSHEA) in 1994, provides limited FDA oversight of supplement manufacturing, standardization, and labeling. This means that two products sold under the same herbal name may contain dramatically different concentrations of active compounds, making clinical risk prediction inherently uncertain. Against this backdrop, the authors searched PubMed, MEDLINE, Google Scholar, and the Cochrane Library for literature published between 1980 and 2023 on perioperative effects of herbal medications, producing a narrative synthesis covering 33 herbs organized by organ-system-based adverse effect categories: coagulation, cardiovascular, central nervous system, pulmonary, renal, and endocrine-metabolic.

Among the most commonly encountered herbs, garlic, ginkgo, and ginseng demonstrated antiplatelet properties that could theoretically potentiate surgical bleeding, while St. John’s wort is well documented as a CYP450 enzyme inducer capable of accelerating the metabolism of numerous anesthetic and analgesic agents. Echinacea, valerian, and kava raised concerns about hepatotoxicity, excessive sedation, or immune modulation. The authors are transparent that randomized controlled trial evidence for most of these specific interactions is scarce, with the majority of claims resting on case reports and mechanistic pharmacologic reasoning. Both the American Society of Anesthesiologists (ASA) and the American Association of Nurse Anesthesiology (AANA) recommend discontinuing herbal supplements one to two weeks before elective surgery, though no formal ASA practice guideline codifies this recommendation, and optimal washout periods for individual herbs have not been validated in clinical trials.

This review does something genuinely useful: it puts 33 herbal medications into a single, clinically organized reference that anesthesia providers can actually consult. The authors deserve credit for their honesty about the evidence base, which is, frankly, thin for most of the specific interactions they describe. What this paper gets right is the framing of the problem. The real danger is not that garlic capsules will definitely cause hemorrhage on the operating table; it is that we do not know, and the patient never mentioned it. That gap between widespread use and near-zero disclosure is the most robust and actionable finding here.

In my own practice, I ask every patient about supplements, herbs, and botanicals as part of the standard intake, not as an afterthought. When someone is heading toward a surgical procedure, I walk through their full supplement list and we discuss which ones carry plausible perioperative risk and which are likely benign. I treat the ASA’s one-to-two-week washout recommendation as reasonable but imperfect guidance, and I always communicate the full list directly to the anesthesia team. The science is not strong enough to panic anyone, but it is more than strong enough to warrant asking the question every single time.

This review sits in a long line of narrative surveys on herbal perioperative risk that began with the landmark 2001 JAMA review by Ang-Lee and colleagues. Two decades later, the fundamental problem has not changed: the evidence base remains heavily reliant on pharmacologic inference and case-level data, and the regulatory environment has not materially improved product standardization. What has changed is the scale of the market and the range of products patients are using, which makes this updated, broader-scope reference timely even if it does not advance the underlying evidence quality. Clinicians should understand that the review’s comprehensiveness, covering 33 herbs, does not imply equivalent certainty across all entries; some interactions, such as St. John’s wort’s CYP450 induction, are well established, while others rest on a single case report or animal study.

From a pharmacological standpoint, the herbs with the strongest mechanistic concern are those affecting platelet aggregation (garlic, ginkgo, ginseng), hepatic enzyme activity (St. John’s wort, goldenseal), and CNS depression (valerian, kava). Clinicians should also be alert to cardiovascular effects: ephedra and yohimbine carry stimulant risk, while hawthorn can potentiate hypotensive effects of anesthetic agents. For patients using cannabis products, which this review does not cover in depth, analogous perioperative concerns exist and should be addressed separately. The single most valuable step any clinician can take is to incorporate explicit, nonjudgmental questioning about herbal and supplement use into every preoperative assessment, document the findings clearly, and communicate them to the anesthesia team well before the day of surgery.

This is a narrative review published in a peer-reviewed anesthesiology journal, synthesizing literature from 1980 to 2023 across multiple databases. It does not employ systematic review methodology, meaning there is no PRISMA framework, no formal inclusion or exclusion criteria, and no risk-of-bias assessment of the cited studies. Narrative reviews occupy a lower tier in the evidence hierarchy than systematic reviews or meta-analyses. The single most important inference constraint is that evidence selection reflects author judgment rather than a reproducible, exhaustive curation process, so the completeness and balance of the literature presented cannot be independently verified.

This review extends and updates a body of work that began prominently with Ang-Lee and colleagues’ 2001 JAMA narrative review on herbal medicines and perioperative care, which identified similar core concerns around garlic, ginkgo, ginseng, and St. John’s wort. Two decades later, the current review broadens the scope to 33 herbs and incorporates literature through 2023, but the fundamental conclusions remain consistent: antiplatelet effects, CYP450 interactions, and cardiovascular instability are the primary pharmacologic concerns, and the controlled clinical evidence confirming these risks in surgical settings remains sparse.

Surgical nursing guidelines, including those published through AORN, have similarly emphasized the importance of preoperative herbal supplement disclosure. Comprehensive pharmacokinetic reference databases corroborate the mechanistic interaction claims outlined here, though rarely with clinical outcome data. The review does not substantially revise established conclusions but consolidates them into a more comprehensive and current reference, which has practical value even in the absence of new primary evidence.

The most likely overinterpretation of this review is treating all 33 herbal medications as carrying equivalent and proven perioperative danger. In reality, the strength of evidence varies enormously across herbs: St. John’s wort’s CYP450 induction is well established through pharmacokinetic studies, while some interaction warnings for less common herbs rest on a single case report or an in vitro observation that may not translate to clinical significance at typical human supplement doses.

A second common misreading is assuming that the ASA’s recommendation to stop herbal supplements one to two weeks before surgery is itself a rigorously evidence-based guideline with validated washout periods. It is better understood as a precautionary consensus recommendation. The review does not provide data quantifying how often herbal supplement use actually causes perioperative complications, and readers should not infer that every undisclosed supplement inevitably leads to an adverse event.

This review contributes a clinically organized, broadly scoped reference on 33 herbal medications and their potential perioperative interactions. It does not establish the frequency or magnitude of actual surgical complications caused by herbal use, and its evidence base for individual herbs ranges from robust to speculative. What it does establish convincingly is that patient non-disclosure is widespread and that routine, explicit preoperative questioning about supplement use is the single most defensible clinical action arising from this literature.

Should I stop all herbal supplements before surgery?

The American Society of Anesthesiologists and the American Association of Nurse Anesthesiology both recommend discontinuing herbal supplements one to two weeks before elective surgery. This is a precautionary recommendation rather than a guideline based on definitive clinical trial evidence. The most important step is to tell your surgical and anesthesia team about every supplement you take so they can help you decide which ones need to be stopped and when.

Which herbal supplements are most concerning before surgery?

Garlic, ginkgo biloba, and ginseng have the most documented antiplatelet effects that could theoretically increase bleeding risk. St. John’s wort is well known to alter how the body metabolizes many medications, including anesthetic drugs. Valerian and kava can cause excessive sedation. However, the strength of evidence varies considerably from herb to herb, and having a plausible interaction does not mean a serious complication is inevitable.

Why do so many patients not tell their doctors about herbal supplements?

Research suggests that many patients do not consider herbal supplements to be “medications” and therefore do not think to mention them. Others may worry about being judged or told to stop products they value. In some cases, doctors simply do not ask. Studies cited in this review estimate that 50% to 70% of surgical patients fail to disclose herbal use, making it essential for clinicians to ask directly and for patients to volunteer this information proactively.

Is the evidence for these herbal interactions strong?

For most herbs, the evidence comes from case reports, laboratory studies, or pharmacologic reasoning rather than controlled clinical trials. A few interactions, such as St. John’s wort’s effect on drug metabolism enzymes, are supported by stronger pharmacokinetic data. The review’s authors are transparent about the limited trial evidence, and readers should understand that “plausible risk” is not the same as “proven danger.” The precautionary approach is reasonable given the stakes of surgery, but it should not be confused with certainty.

Does this review cover cannabis or CBD products?

This review focuses on traditional herbal supplements and does not provide an in-depth analysis of cannabis or CBD products, which carry their own set of perioperative pharmacologic considerations. Patients using cannabis or CBD before surgery should discuss these products with their anesthesia provider separately, as analogous concerns about sedation, cardiovascular effects, and drug interactions apply.

Have thoughts on this? Share it: