Fifteen Years of Data Reveal Blind Spots in Korea’s Herbal Medicine Safety Surveillance

Herbal medicine occupies a central place in Korean healthcare, dispensed daily in traditional Korean medicine clinics as decoctions, granules, powders, and extracts. Yet a new fifteen-year analysis from one of the country’s integrative medical centers suggests that the national system designed to catch herbal drug hazards is seeing only part of the picture. The study, published in BMC Complementary Medicine and Therapies, examined adverse event reports collected between January 2010 and December 2024 at Dongguk University Ilsan Hospital and its affiliated Oriental Hospital, and found that nearly a quarter of herbal-related safety reports never made it into the national pharmacovigilance database at all.

The retrospective descriptive study, conducted by Mikyung Kim and Dong-jun Choi of the Department of Internal Medicine and the Regional Pharmacovigilance Center for Korean Herbal Medicines, mined the shared adverse event reporting databases of the two hospitals. After removing duplicates, the researchers identified 454 reports in which an herbal medicine was recorded as the suspected agent. That figure represents just 1.2 percent of the 38,367 adverse event reports handled by the centers over the entire study period, a proportion that itself hints at how rarely herbal products are formally flagged as suspected causes of harm even in institutions where they are prescribed routinely.

The most striking finding concerns the regulatory status of the products involved. Non-licensed oral herbal medicines accounted for the largest share of suspected agents at 48.7 percent, narrowly exceeding the 47.0 percent share of oral herbal medicine products licensed by Korea’s Ministry of Food and Drug Safety. At the report level, 51.3 percent of cases involved at least one non-licensed formulation. These are preparations that fall outside the standard regulatory licensing pathway, including individualized herbal decoctions compounded for specific patients, and they are precisely the products that national databases built around licensed pharmaceuticals are least equipped to track.

The clinical profile of the reported events followed recognizable patterns. Gastrointestinal disorders were the most frequently reported system organ class, classified according to the Medical Dictionary for Regulatory Activities, followed by skin and subcutaneous tissue disorders. Among the 572 drug-event pairs with evaluable causality assessments, the overwhelming majority, 87.7 percent, were judged merely possible, while cases assessed as certain were vanishingly rare at 0.2 percent. That distribution reflects a familiar limitation of spontaneous reporting: without rechallenge or unambiguous temporal and biological evidence, causality in herbal medicine cases usually remains provisional, complicated by polypharmacy, delayed onset, and the multi-component nature of herbal formulas.

The surveillance gap emerges most clearly when the researchers compared reports that were forwarded to the national system with those that were not. Overall, 24.0 percent of the 454 reports were never submitted to national pharmacovigilance. The differences between the two groups were stark and statistically significant. Non-submitted reports far more frequently involved non-licensed herbal medicines, at 83.5 percent compared with 41.2 percent of submitted reports. They were far less likely to include documented clinical severity grading, at 7.3 percent versus 59.1 percent, and far less likely to contain a causality assessment, at 26.6 percent versus 98.8 percent, with p values below 0.001 across all three comparisons.

In other words, the reports most likely to slip through the cracks were those describing the products least visible to regulators, and those least complete in the clinical detail that pharmacovigilance assessment depends on. Severity grading in the study followed the Common Terminology Criteria for Adverse Events, the standardized scale used in oncology and increasingly across drug safety work, while causality was evaluated within the framework of individual case safety reports submitted through Korea’s adverse event reporting infrastructure. A report lacking both a severity grade and a causality judgment offers national assessors little to work with, which may partly explain why incomplete cases were not prioritized for submission.

The structural reasons behind the gap are not difficult to infer from the Korean context. Traditional Korean medicine doctors routinely prescribe individualized multi-herb decoctions that are compounded fresh for each patient. These formulations do not carry product licenses in the way manufactured drugs do, so they sit awkwardly within a reporting system whose data structures, coding conventions, and regulatory workflows were designed around licensed medicinal products. A suspected reaction to a ten-herb decoction does not map neatly onto a single product code, and the paper’s authors argue that the current pharmacovigilance framework therefore does not fully capture the range of herbal medicines actually used in real-world Korean practice.

The study’s setting gives its findings particular weight. Dongguk University Ilsan Oriental Hospital hosts a regional pharmacovigilance center specifically dedicated to Korean herbal medicines, one of the institutional mechanisms Korea has built to strengthen reporting from the traditional medicine sector. If, even at a center with dedicated reporting infrastructure, a quarter of herbal adverse event reports failed to reach the national system and half involved non-licensed formulations, the authors suggest that the true blind spots in less specialized settings are likely to be larger. Fifteen years of data also lend temporal depth, spanning a period in which Korea expanded its pharmacovigilance networks and electronic reporting systems considerably.

The methodological caveats are worth noting. This was a single-center retrospective descriptive analysis, so the absolute numbers and proportions cannot be generalized to the whole country, and spontaneous reporting data inherently capture only a fraction of adverse events that actually occur, with underreporting the norm rather than the exception across all drug classes. The study was exempted from full ethical review because it used de-identified data from previously collected reports. Still, the internal comparison between submitted and non-submitted reports is the analytically powerful part of the design, because both groups came from the same institutions over the same period, isolating the characteristics that predict whether a case enters national surveillance.

The authors’ conclusions point toward concrete reforms: broader surveillance coverage that explicitly encompasses non-licensed formulations, improved documentation of clinical severity and causality assessments at the point of reporting, and stronger reporting support for traditional Korean medicine professionals, who are often the first and only clinicians positioned to recognize a herbal adverse event. As herbal medicine use grows globally and integrative care models spread, the Korean experience offers a cautionary lesson for any country attempting to fold traditional formulations into regulatory safety systems built for licensed pharmaceuticals. A safety net with holes in exactly the places where the most-used products fall through is, the study implies, a net that needs reweaving.

Subject of Research: Herbal medicine adverse event reporting and pharmacovigilance surveillance gaps in traditional Korean medicine

Article Title: Real-world patterns of herbal medicine-related adverse event reports and surveillance gaps in national pharmacovigilance: a 15-year retrospective analysis from a single integrative medical center in Korea

Article References: Kim, M., & Choi, D.-J. (2026). Real-world patterns of herbal medicine-related adverse event reports and surveillance gaps in national pharmacovigilance: a 15-year retrospective analysis from a single integrative medical center in Korea. BMC Complementary Medicine and Therapies. https://doi.org/10.1186/s12906-026-05532-x

Image Credits: AI Generated

DOI: 10.1186/s12906-026-05532-x

Keywords: pharmacovigilance, herbal medicine, adverse event reporting, traditional Korean medicine, drug safety, non-licensed formulations, spontaneous reporting, causality assessment, real-world data, Korea, integrative medicine, surveillance gap