Thai Pharmacies Agree on What Drives Herbal Medicine Sales, Expert Study Finds

Herbal medicinal products have become a quiet fixture of everyday healthcare in Thailand, lining the shelves of community pharmacies from Bangkok to the northern provinces. Yet despite their popularity, the factors that determine which products are available, how they are promoted, and how consumers come to use them have never been systematically mapped. A new study published in PLOS One offers the most structured attempt to date, using a rigorous consensus-building technique to identify what a multidisciplinary panel of Thai experts considers most relevant to the availability and consumption of herbal medicines in pharmacies. The findings arrive at a moment when governments across Southeast Asia are grappling with how to integrate traditional and complementary medicine into modern health systems without compromising safety or evidence-based practice.

The research team, led by Thanat Nakaphan and colleagues including Monthaka Teerachaisakul, Chatchai Chaotham, and Krit Pongpirul, employed an electronic Delphi study, a method designed to distill reliable group judgment from a panel of specialists who never meet face to face. The Delphi technique, developed during the Cold War era for technological forecasting, has since become a standard tool in health services research for situations where hard evidence is sparse and expert opinion must serve as a bridge. In an e-Delphi, participants complete successive rounds of questionnaires online, receiving anonymous feedback from previous rounds so that their subsequent ratings can converge, or fail to converge, toward shared positions. The approach minimizes the groupthink that can plague committee meetings, because no participant knows who holds which view and dominant personalities cannot steer the outcome.

For this study, the researchers assembled a panel of 30 experts drawn from multiple disciplines relevant to herbal medicine in Thailand, spanning pharmacy practice, pharmacology, traditional medicine, and related fields. Multidisciplinary representation matters here because herbal products sit at the intersection of several professional worlds: pharmacists trained in evidence-based therapeutics, practitioners of Thai traditional medicine with its own diagnostic and therapeutic frameworks, regulators responsible for product registration, and researchers evaluating clinical efficacy. Each expert rated the relevance and impact of candidate factors using a 7-point Likert scale, the familiar survey instrument that ranges from strong disagreement to strong agreement. Across three structured rounds, the panel worked through 34 distinct factors that the research team had identified as potentially relevant to whether herbal medicinal products are stocked in pharmacies and whether consumers ultimately purchase and use them.

What distinguishes this study methodologically is its explicit and unusually transparent definition of consensus. Rather than relying on arbitrary thresholds such as a simple percentage agreement, the researchers applied a concept borrowed from rough set theory, a mathematical framework for handling uncertainty and vagueness in data. They calculated a Quality of the Lower Approximation, or QL score, for each factor, with consensus declared only when the QL reached at least 0.75. In practical terms, this measure captures how consistently the panel’s ratings cluster in the region of agreement, penalizing factors that divide opinion even when a numerical majority leans one way. The choice reflects a growing recognition in Delphi literature that conventional cutoffs can mask genuine disagreement and that more formal, reproducible criteria strengthen the credibility of expert consensus exercises.

The results were striking in their selectivity. Of the 34 factors assessed, 25 achieved consensus, organized into four coherent domains: the herbal medicinal products themselves, the information that accompanies them, the professional responsibilities of pharmacy staff, and the operational characteristics of pharmacies. Nine factors failed to reach the threshold, suggesting that even among seasoned experts there remain genuine points of contention about what drives herbal medicine dynamics in Thai pharmacy settings. That a substantial minority of factors did not achieve consensus is arguably as informative as the list of those that did, because it flags precisely where future empirical research is most needed and where policy debates are likely to remain contested.

Among all 34 candidates, one factor stood apart: the National List of Essential Herbal Drugs, which received the highest possible consensus score of 1.00, meaning the panel was unanimous in its judgment of relevance. Thailand’s essential herbal drugs list, modeled conceptually on the World Health Organization’s essential medicines list, identifies herbal products considered sufficiently effective, safe, and cost-effective to merit prioritization in the national health system. The perfect agreement among experts signals a shared conviction that government endorsement and listing status exert powerful influence over what pharmacies stock and what consumers trust. Products appearing on an official national list carry an implicit seal of legitimacy that shapes both supply chains and patient expectations, and the finding suggests experts see this policy instrument as the single most consequential lever available.

Equally notable is the performance of the product information domain, in which all nine assessed factors reached consensus. This domain encompasses the quality, completeness, and accessibility of the information that accompanies herbal products, from labeling and package inserts to the verbal guidance provided at the counter. The unanimous or near-unanimous agreement across every information-related factor underscores a persistent anxiety in herbal medicine research: consumers frequently choose these products with limited understanding of their active ingredients, appropriate indications, potential side effects, and interactions with conventional drugs. Because herbal products in many jurisdictions, including Thailand, are often regulated differently from pharmaceutical drugs, the informational infrastructure surrounding them can be thinner, leaving both pharmacists and customers to navigate uncertainty. The panel’s verdict suggests that closing this information gap is regarded as central to promoting appropriate consumption.

The professional domain yielded its own revealing pattern. Factors achieving consensus included the recommendation behavior of pharmacy personnel, knowledge of herbal medicinal product categories, and knowledge of evidence-based efficacy and safety. In Thailand, pharmacists are often the first and sometimes the only health professionals that consumers consult before purchasing herbal remedies, which places enormous weight on the accuracy of counter-level advice. A pharmacist who cannot distinguish among registered herbal drugs, traditional preparations, and dietary supplements, or who lacks familiarity with the clinical evidence base, may inadvertently steer patients toward inappropriate products or fail to flag dangerous interactions with prescribed medications. The experts’ consensus on these competency factors effectively issues a challenge to pharmacy education and continuing professional development: if recommendation practices shape consumption, then training standards shape public health.

The fourth domain, pharmacy operations, broadens the picture beyond the counter and into the commercial and structural environment. Consensus factors here included pharmacy type, business model, participation in national health programs, and location. These findings acknowledge that herbal medicine availability is not merely a matter of professional knowledge or consumer preference but of economics and geography. A pharmacy’s business model determines its incentive to stock herbal lines, which may carry different margins than conventional pharmaceuticals. Participation in national health schemes can channel patient traffic and influence formularies. Location shapes the customer base, the competitive landscape, and the cultural context in which herbal remedies are sought. By elevating these operational variables to consensus status, the panel signals that interventions targeting herbal medicine use must engage with the commercial realities of community pharmacy rather than treating it as a neutral dispensing point.

The study’s authors are careful about scope, presenting the consensus framework as a foundation rather than a conclusion. The identified factors now constitute a structured agenda for empirical investigation: researchers can measure how strongly each consensus factor actually predicts availability and consumption in real pharmacies, test interventions targeting the most influential variables, and track how policy changes, such as revisions to the essential herbal drugs list, ripple through the system. The findings may also inform regulatory and professional bodies designing guidelines for product information, competency standards for pharmacists, and operational policies for pharmacy networks. As herbal medicine consumption continues to grow in Thailand and across the region, the study demonstrates that rigorous consensus methods can bring analytical order to a field often dominated by tradition, marketing, and anecdote, offering health authorities a defensible starting point for evidence-informed action.

Subject of Research: Expert consensus on factors affecting the availability and consumption of herbal medicinal products in Thai pharmacies

Article Title: Expert consensus on the availability and consumption of herbal medicinal products in Thai pharmacies: An e-Delphi study

Article References: Nakaphan, T., Teerachaisakul, M., Chaotham, C., & Pongpirul, K. (2026). Expert consensus on the availability and consumption of herbal medicinal products in Thai pharmacies: An e-Delphi study. PLOS One, 21(10), e0360797. https://doi.org/10.1371/journal.pone.0360797

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360797

Keywords: herbal medicine, Thailand, pharmacies, e-Delphi study, expert consensus, National List of Essential Herbal Drugs, product information, pharmacist knowledge, pharmacy operations, PLOS One, traditional medicine, health policy