ABSTRACT
Background
In South Korea, a substantial volume of prescription psychotropics is dispensed outside the national health insurance reimbursement system, creating a pharmacovigilance blind spot. We investigated nationwide utilization patterns of medical narcotics to identify potential safety signals using the Narcotics Information Management System (NIMS) database.
Methods
This population‐based descriptive study analyzed NIMS data covering all controlled substances dispensed in South Korea from January 2019 to May 2023. We examined overall trends and stratified patterns for anorexiants and ADHD medications. Prescription volumes were expressed as estimated dispensing units (EDU) per 1000 persons per month using resident registration population data as denominators.
Results
Among 3.1 million dispensing cases, anorexiants exhibited a stark gender disparity. Women at primary care clinics received approximately 440 EDUs per 1000 women per month—approximately 15 times the volume dispensed to men—concentrated among women aged 30–49, suggesting widespread prescribing outside approved indications for aesthetic weight management. ADHD medications were predominantly dispensed to males, with the largest gender gap observed in adolescents aged 10–19 and a progressively narrowing disparity in older age groups. Dispensing rates for both drug classes increased steadily over the study period, with the most pronounced rise in ADHD medications observed after the resumption of in‐person schooling following COVID‐19 disruptions.
Conclusion
This study provides the first population‐level analysis of medical narcotics utilization in South Korea's non‐reimbursed sector. The disproportionate exposure of young women to psychotropic anorexiants constitutes a compelling pharmacovigilance signal. Addressing this requires not only an integrated data infrastructure linking NIMS with national health insurance records, but also the restoration of meaningful professional oversight over prescribing outside the reimbursement system.
Keywords: drug utilization, medical narcotics, non‐reimbursed prescribing, pharmacoepidemiology, pharmacovigilance, South Korea
Key Points
This study provides the first nationwide, population‐based analysis of medical narcotics utilization in South Korea, including the non‐reimbursed sector, addressing a major gap in national pharmacovigilance.
Anorexiant use showed an extreme gender disparity: women at primary care clinics received approximately 15 times the dispensing volume of men, concentrated among women aged 30–49, and consistent with widespread prescribing outside approved indications.
ADHD medication dispensing showed persistent male predominance under 40 age groups, with steady increases over time—particularly among school‐aged children following COVID‐19‐related disruptions to in‐person schooling.
The scale of non‐reimbursed psychotropic dispensing raises serious concerns regarding patient safety and the weakening of professional gatekeeping in prescribing outside the insurance system.
Integrated pharmacovigilance linking NIMS with national health insurance data, combined with professional accountability mechanisms, is critically needed to protect vulnerable populations.
Plain Language Summary
In South Korea, many controlled medicines—including appetite suppressants and ADHD medications—are prescribed outside the national health insurance system, where their use is not closely monitored for safety. Using a national database that records all legally dispensed controlled substances, this study examined utilization patterns of these medicines between 2019 and 2023. We found a striking gender disparity in appetite suppressant use: women, particularly those aged 30 to 49, received far larger amounts than men, with most prescriptions issued at primary care clinics. This pattern suggests that these drugs are widely prescribed for cosmetic weight management rather than for medically approved reasons. ADHD medication use was predominantly concentrated among adolescent males, though use among adults increased steadily over time, and a sharp rise was observed in school‐aged children following the return to in‐person schooling after the COVID‐19 pandemic. These findings reveal that large numbers of people—especially young women—may be exposed to potentially harmful controlled substances with insufficient clinical oversight. Our study calls for better systems to monitor prescribing practices and ensure professional accountability, particularly for medicines dispensed outside the public insurance system.
1. Introduction
Internationally, the misuse of controlled substances—drugs regulated due to their potential for abuse and dependence, including medical narcotics (마약류) under South Korea's Narcotics Control Act [1]—is a significant public health concern. As evidenced by the magnitude of drug overdose deaths reported in countries like the United States and the United Kingdom, drug abuse and dependence have a profound impact on population health [2, 3]. According to estimates of the global burden of disease, drug use accounted for 1.3% of all disability‐adjusted life‐years (DALYs) in 2016 [4]. While a wastewater epidemiology study has confirmed that non‐medical stimulant use in South Korea is markedly lower than in Western countries [5], the harmful utilization of prescription drugs through legitimate medical channels warrants closer scrutiny [6, 7].
South Korea presents a unique paradox in drug consumption patterns. Despite markedly low non‐medical drug use, South Korea exhibits paradoxically high consumption of medical narcotics—dispensed largely outside the National Health Insurance (NHI) reimbursement system and therefore beyond routine pharmacovigilance coverage. Wastewater epidemiology data illustrate this contrast: consumption of phentermine, a widely prescribed anorexiant, is 5.3 times higher in South Korea than in the United States [5]. Following the change of administration in 2022, the newly inaugurated conservative government of South Korea has declared a “war on drugs”, intensifying criminal justice responses to illicit drug use while expanding regulatory oversight over medical narcotics [8, 9, 10, 11]. However, a critical gap remains in monitoring systems. Most pharmacoepidemiologic studies rely on NHI claims data, which systematically exclude non‐reimbursed prescriptions—a sector where a substantial volume of prescription psychotropics is dispensed. In South Korea, the anorexiant prescriptions are not covered under NHI reimbursement and are therefore dispensed entirely in the non‐reimbursed sector. Within this sector, prescriptions may be either on‐label—where patients meet approved eligibility criteria such as BMI thresholds and treatment duration limits—or off‐label, where these criteria are not met. Off‐label prescriptions require prior Health Insurance Review & Assessment Service (HIRA) approval but, in practice, are frequently dispensed without it, constituting a regulatory gray area [12].
This data gap is particularly concerning given the potential safety risks associated with these drugs. For instance, phentermine, widely prescribed for weight control, carries serious psychiatric and cardiovascular risks. Studies have consistently shown that serious adverse events, including psychosis and mood disorders, are frequently associated with anorexiant use in South Korea [13, 14, 15, 16]. Furthermore, signal detection studies using adverse event reporting systems have identified phentermine as a leading cause of drug‐related adverse events [17].
These safety risks are unevenly distributed across the population. Globally, while illicit drug use is often more prevalent among men, women are frequently more prone to problems associated with prescription drug misuse [18, 19]. In South Korea, this gendered disparity is suspected to be pronounced in the off‐label use of anorexiants, yet population‐level evidence remains scarce due to the limitations of insurance data. Conversely, ADHD medications show a different pattern of utilization, raising questions about trends in diagnosis and treatment across different demographic groups.
To address these gaps, the Korean Narcotics Information Management System (NIMS) offers a crucial resource. Unlike insurance claims data, NIMS monitors the full lifecycle of medical narcotics and captures all dispensing records regardless of insurance status [20, 21]. Leveraging this nationwide population‐based dataset, this study aims to (1) investigate the overall trends in medical narcotics utilization in South Korea from 2019 to 2023, and (2) characterize demographic patterns in the use of anorexiants and ADHD medications to identify potential safety signals in the non‐reimbursed market.
2. Methods
2.1. Data Source
The Big Data Service for Medical Narcotics (https://data.nims.or.kr) is a public data portal managed by the Korea Institute of Drug Safety & Risk Management (KIDS) under the Ministry of Food and Drug Safety (MFDS). The system compiles information from two sources: the Narcotics Information Management System (NIMS) and the Narcotics Handling Report System (NHRS), both designed to monitor the full lifecycle of medical narcotics, including manufacturing, distribution, prescription, and disposal [20, 21]. Dispensing records are submitted electronically by licensed pharmacies and medical institutions at the point of dispensing, enabling near‐complete capture of all outpatient controlled substance transactions regardless of insurance status. Unlike the NHI claims database, which covers only reimbursed prescriptions, NIMS captures all dispensing records of controlled substances regardless of insurance status. This feature is critical for this study, as a significant proportion of prescription psychotropic drugs (e.g., anorexiants) are dispensed in the non‐reimbursed sector, including both on‐label and off‐label use, and are therefore absent from standard insurance claims data (See Table A1 for dataset comparison and Table A2 for details).
2.2. Study Population and Data Variables
We analyzed aggregated prescription data spanning 53 months from January 2019 to May 2023. The dataset included all records of “dispensing” (drugs dispensed by pharmacies for outpatient use) and “administration” (drugs administered directly within medical facilities). The data were provided in an aggregated format, stratified by demographic and institutional attributes. Key variables included: (1) Patient demographics: Sex and age group (10‐year intervals), (2) Provider characteristics: Institution type (General Hospital, Hospital, Long‐term Care Hospital, Clinic, and Others including public health centers and veterinary hospitals) and region (Seoul metropolitan area, other metropolitan cities, and provinces), and (3) Drug characteristics: Therapeutic category (e.g., analgesics, sedatives, anorexiants, antiepileptics, antidepressants, anxiolytics, anesthetics, ADHD medications) and active ingredient. Veterinary hospitals are included as they are licensed to handle certain controlled substances under the Narcotics Control Act and are therefore captured in the NIMS database. Of note, the antidepressant category in the NIMS database comprises esketamine only, as it is the sole antidepressant classified as a controlled substance under South Korea's Narcotics Control Act; this category does not include commonly prescribed antidepressants such as SSRIs or SNRIs. A complete list of all active ingredients included in each drug category is provided in Table A2. Since the aggregated nature of the data precluded the linkage of individual patient records across multiple visits, the primary unit of analysis was the dispensing event (case). Each row in the dataset represented the total count of dispensing events and total volume (units) for a unique combination of the stratified variables.
2.3. Target Drug Selection
For detailed analysis, we prioritized two specific drug classes: anorexiants (e.g., phentermine, phendimetrazine, diethylpropion, mazindol) and ADHD medications (e.g., methylphenidate). These classes were selected based on (1) their clearly defined clinical indications—anorexiants are approved for short‐term treatment of obesity (BMI ≥ 30 kg/m2, or ≥ 27 kg/m2 with obesity‐related comorbidities), and ADHD medications for the treatment of attention‐deficit/hyperactivity disorder—and (2) significant public health concerns regarding their use beyond these approved indications in the non‐reimbursed sector and distinctive patterns of demographic exposure that warrant safety monitoring.
2.4. Exposure Assessment and Unit Standardization
The primary measure of exposure was the volume of drug utilization. As the aggregated NIMS dataset provided the number of packaging units (e.g., tablets, capsules) without consistent ingredient‐weight information (mg per unit), direct calculation of WHO‐defined daily doses (DDD) was not feasible [22]. To address this, we applied a unit‐based standardization method. We defined an estimated dispensing unit (EDU) as a single tablet, capsule, or ampoule, treating it as a proxy for a single dose. While this approach does not account for dosage strength variations, it provides a consistent metric to estimate the scale of prescription volume and assess temporal trends across different drug formulations. We aggregated these EDUs to calculate the monthly total dispensing volume.
2.5. Statistical Analysis
We performed descriptive analyses to examine trends in prescription volume by year, month, and drug category. The Administration‐to‐Dispensing (AtD) ratio was calculated to assess the proportion of in‐hospital usage versus outpatient dispensing. Data were stratified by patient demographics, provider type, and region, as defined in the Study Population and Data Variables section. We specifically analyzed the gender ratio in prescription counts and volumes to identify disparities. To facilitate interpretation and international comparability, utilization rates for anorexiants and ADHD medications were additionally expressed as EDU per 1000 persons per month. Population denominators were derived from the Resident Registration Population Statistics by the Ministry of the Interior and Safety (MOIS), stratified by sex and 10‐year age group [23]. All analyses were conducted using aggregated data; therefore, individual‐level statistical adjustment was not applicable. We used Claude Sonnet 4 (Anthropic) to assist with English language editing and the presentation of figures. The use of this tool was strictly limited to language refinement and figure presentation; it was not employed for data analysis, statistical modeling, or the generation of research findings.
3. Results
3.1. General Characteristics of Total Medical Narcotics Utilization
Between January 2019 and May 2023, the NIMS database recorded a total of 3 110 847 dispensing cases and 1 125 869 administration cases (Table 1). The overall Administration‐to‐Dispensing (AtD) ratio was 36.2%. The annual volume of dispensing cases showed a steady increase from 673 375 in 2019 to 734 195 in 2022.
TABLE 1.
Basic characteristics of NIMS prescription data.
| Classification | Dispensing | Administration | AtD ratio a | ||
|---|---|---|---|---|---|
| Total | 3 110 847 (100.0) | 1 125 869 (100.0) | 36.2 | ||
| Year | 2019 | 673 375 (21.6) | 247 413 (22.0) | 36.7 | |
| 2020 | 676 680 (21.8) | 248 577 (22.1) | 36.7 | ||
| 2021 | 726 176 (23.3) | 262 613 (23.3) | 36.2 | ||
| 2022 | 734 195 (23.6) | 260 416 (23.1) | 35.5 | ||
| 2023 (~May) | 300 421 (9.7) | 106 850 (9.5) | 35.6 | ||
|
Gender and Age group b |
Male | Total | 1 740 951 (56.0) | 643 639 (57.2) | 37.0 |
| Child and Adolescent (0–19) | 140 274 (4.5) | 52 258 (4.6) | 37.3 | ||
| Adults (20–59) | 763 377 (24.4) | 283 516 (25.2) | 37.1 | ||
| Elderly (60 and over) | 837 300 (26.9) | 307 865 (27.3) | 36.8 | ||
| Female | Total | 1 369 882 (44.0) | 476 127 (42.3) | 34.8 | |
| Child and Adolescent (0–19) | 131 464 (4.2) | 49 834 (4.4) | 37.9 | ||
| Adults (20–59) | 763 144 (24.5) | 296 823 (26.4) | 38.9 | ||
| Elderly (60 and over) | 675 274 (21.7) | 229 670 (20.4) | 34.0 | ||
| Institution type c | General Hospital | 1 265 547 (40.7) | 162 580 (14.4) | 12.8 | |
| Hospital | Hospital, Dental hospital, Korean medical hospital | 702 882 (22.6) | 307 636 (27.3) | 44.8 | |
| Long‐term Hospital | Long‐term care hospital, Mental health hospital | 487 476 (15.6) | 155 637 (13.8) | 31.4 | |
| Clinics | Medical clinic, Dental clinic | 598 437 (19.2) | 448 952 (39.9) | 75.0 | |
| Others | Health and Medical Clinic, Public health (sub‐)center, Veterinary hospital | 56 505 (2.0) | 51 064 (4.5) | 90.4 | |
| Region | Seoul metropolitan area | Seoul, Incheon, Gyeonggi | 875 697 (28.2) | 305 790 (27.1) | 34.9 |
| Metropolitan cities | Busan, Daegu, Gwangju, Daejeon, Ulsan, Sejong | 1 013 282 (32.6) | 330 702 (29.4) | 32.6 | |
| Province | Other provinces | 1 221 868 (39.2) | 489 377 (43.5) | 40.1 | |
| Drug type | Narcotics | Total | 700 480 (22.5) | 251 655 (22.4) | 35.9 |
| Anesthetics | 135 960 (4.4) | 82 745 (7.3) | 60.9 | ||
| Analgesics | 424 326 (13.6) | 134 119 (11.9) | 31.6 | ||
| Antitussives | 140 194 (4.5) | 34 791 (3.1) | 24.8 | ||
| Psychotropics | Total | 2 410 367 (77.5) | 874 214 (77.6) | 36.3 | |
| Anesthetics | 173 295 (5.6) | 153 223 (13.6) | 88.4 | ||
| Anesthetics (Veterinary) | — | 12 722 (1.1) | — | ||
| Analgesics | 102 616 (3.3) | 44 541 (4.0) | 43.4 | ||
| Antitussives | 47 040 (1.5) | 1077 (0.1) | 2.3 | ||
| Sedatives | 598 385 (19.2) | 221 679 (19.7) | 37.0 | ||
| Antiepileptics | 235 925 (7.6) | 70 257 (6.2) | 29.8 | ||
| Anxiolytics | 968 443 (31.1) | 321 148 (28.5) | 33.2 | ||
| Antidepressants | 730 (0.0) | 574 (0.1) | 78.6 | ||
| Anorexiants | 149 254 (4.8) | 8729 (0.8) | 5.8 | ||
| ADHD medications | 134 679 (4.3) | 40 264 (3.6) | 29.9 | ||
AtD ratio means administration to dispensing ratio.
Unknown group was omitted.
Unit: Cases, %.
Demographically, male patients accounted for the majority of cases in both dispensing (56.0%) and administration (57.2%). Age‐stratified analysis revealed that the elderly (aged 60 and over) represented the largest proportion of users, particularly in dispensing cases (26.9% for males and 21.7% for females). Geographically, non‐metropolitan provinces accounted for the highest share of dispensing cases (39.2%) compared to the Seoul metropolitan area (28.2%) and other metropolitan cities (32.6%).
Utilization patterns varied significantly by institution type. General hospitals accounted for the largest share of dispensing cases (40.7%) but exhibited a low AtD ratio of 12.8%. In contrast, primary clinics, while comprising 19.2% of dispensing cases, were responsible for a substantial 75.0% of administration cases (AtD ratio 75.0%), highlighting their predominant role in in‐facility drug administration.
Regarding drug classification, psychotropics constituted the majority (77.5%) of all records, driven largely by anxiolytics (31.1%) and sedatives (19.2%). The AtD ratios reflected the clinical usage of each drug class; anesthetics (both narcotic and psychotropic) showed high administration rates (60.9% and 88.4%, respectively). Conversely, anorexiants demonstrated one of the lowest AtD ratios (5.8%), indicating that these agents are primarily dispensed for outpatient use rather than administered within facilities.
Figure 1 illustrates gender disparities in narcotics utilization across therapeutic categories, expressed as the female‐to‐male ratio in total dispensing volume on a log scale. Anorexiants exhibited the most pronounced gender imbalance, with a female‐to‐male volume ratio of 14.6, far exceeding all other categories. Conversely, ADHD medications showed clear male predominance (ratio = 0.4). The remaining categories—including analgesics, anesthetics, anxiolytics, and sedatives—clustered near parity (ratio range: 0.8–1.6), with narcotic drug (ND) subcategories generally showing more balanced utilization than their psychotropic (PS) counterparts.
FIGURE 1.
Gender disparities in dispensing volume across medical narcotics categories in South Korea, January 2019–May 2023. Each circle represents a therapeutic drug category, positioned on the x‐axis according to the female‐to‐male ratio in total dispensing volume (log scale). Circle size reflects total dispensing volume across the study period. Anorexiants exhibited the most pronounced female predominance (F/M ratio = 14.6), while ADHD medications showed male predominance (F/M ratio = 0.4). Most other categories clustered near parity (ratio ≈1.0). *Abbreviations: PS, Psychotropic Substance; ND, Narcotic Drug.
3.2. Utilization Trends in Anorexiants
Anorexiant utilization demonstrated marked gender stratification and seasonality. By active ingredient, phendimetrazine and phentermine dominated total dispensing volume through the study period (Figure 2). Among the overall population, phendimetrazine averaged approximately 230 EDUs per 1000 persons per month, while phentermine averaged approximately 130 EDUs per 1000 persons per month. These figures were substantially higher among women dispensed at primary care clinics: phendimetrazine averaged approximately 440 EDUs per 1000 women per month and phentermine approximately 230 EDUs per 1000 women per month (Figure 2B), underscoring the concentration of anorexiant use in this subgroup (see Table A3 for monthly prescription counts and volume per case). Distinct seasonal patterns were observed, with prescription volumes peaking during the summer months (June–August) and declining in winter, particularly pronounced among women. Following the implementation of stricter narcotic safety regulations in May 2022, a modest decline in phentermine volume was observed, with no compensatory increase observed for other agents. Notably, dispensing records for lorcaserin were identified even after its market withdrawal in February 2020 (see Table A4,A5).
FIGURE 2.
Monthly Anorexiant Dispensing Volume by Drug Type, January 2019–May 2023. Panel (A) shows total dispensing volume across all providers, expressed as estimated dispensing units (EDU) per 1000 persons per month. Panel (B) shows dispensing volume among women at primary care clinics, expressed as EDU per 1000 women per month. Phendimetrazine and phentermine accounted for the majority of total volume throughout the study period. The shaded area indicates the period following strengthened narcotics regulations (after May 2022). Lorcaserin prescriptions were identified at low levels after its market withdrawal in February 2020. *Data Source: Korean Narcotics Information Management System (NIMS).
Age‐stratified analysis indicated that utilization was concentrated among women aged 30–39 and 40–49, averaging approximately 1800 and 1500 EDUs per 1000 women per month, respectively, followed by women aged 20–29 (approximately 850 EDUs per 1000 women per month) (Figure 3). Notably, prescriptions were also identified among women aged 0–19 throughout the study period, despite regulatory restrictions prohibiting anorexiant use in minors, representing a potential safety signal warranting further investigation.
FIGURE 3.
Age‐specific monthly anorexiant dispensing volume among women at primary care clinics, January 2019–May 2023. Monthly dispensing volume is expressed as estimated dispensing units (EDU) per 1000 women per month, stratified by age group. Women aged 30–39 and 40–49 consistently showed the highest utilization rates, averaging approximately 1800 and 1500 EDUs per 1000 women per month, respectively. Seasonal peaks were observed during the summer months. The shaded area indicates the period following strengthened narcotics regulations (after May 2022). Prescriptions to women aged 0–19 were observed despite regulatory restrictions on anorexiant use in minors. *Data Source: Korean Narcotics Information Management System (NIMS).
3.3. Utilization Trends in ADHD Medications
In contrast to anorexiants, ADHD medications were predominantly prescribed to males across all age groups (Figure 4). Among males, dispensing rates increased from approximately 55 to 90 EDUs per 1000 males per month over the study period, compared to 22 to 43 EDUs per 1000 females per month, indicating a persistent but gradually widening gender gap. The male‐to‐female prescription ratio exceeded the diagnostic ratio across most age groups, particularly among children under 10 (Table 2). Age‐specific analysis revealed that the 10–19 age group showed the highest dispensing rates, with males in this group averaging approximately 300–450 EDUs per 1000 males per month. A clear seasonal pattern was observed across school‐aged groups, with dispensing volumes increasing during academic semesters (March–June, September–November) and declining during vacation periods, suggesting that ADHD diagnosis and treatment initiation are closely tied to the school calendar. This seasonal pattern was particularly pronounced among males aged 10–19 and under 10. Notably, a sharp increase in dispensing among boys under 10 was observed in mid‐2022, coinciding with the full resumption of in‐person schooling following COVID‐19‐related disruptions, which may have facilitated deferred ADHD evaluations and treatment initiation.
FIGURE 4.
Monthly ADHD medication dispensing volume by sex and age group, January 2019–May 2023. Panel A shows total monthly dispensing volume by sex, expressed as EDU per 1000 persons per month. Panel B shows age‐specific dispensing volume by sex. Male predominance was observed across all age groups throughout the study period. Dispensing volumes increased steadily over time, with the most pronounced increases among males aged 10–19 and under 10. Seasonal variation aligned with the academic calendar was apparent in school‐aged groups. The shaded area indicates the period following strengthened narcotics regulations (after May 2022). *Data Source: Korean Narcotics Information Management System (NIMS).
TABLE 2.
Number of patients diagnosed with ADHD (2022) and gender ratio in ADHD medication prescription*.
| Age group | Number of patients | Gender ratio (Male/Female) | Gender ratio in prescriptions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Total | Male | Female | 2019 | 2020 | 2021 | 2022 | 2023 | ||
| Under 10 | 37 609 | 30 199 | 7410 | 4.1 | 5.5 | 5.0 | 4.5 | 4.5 | 4.5 |
| 10–19 | 53 652 | 40 224 | 13 428 | 3.0 | 3.9 | 3.8 | 3.6 | 3.4 | 3.2 |
| 20–29 | 33 672 | 16 959 | 16 713 | 1.0 | 2.3 | 2.1 | 1.8 | 1.5 | 1.4 |
| 30–39 | 16 376 | 8724 | 7652 | 1.1 | 2.0 | 2.0 | 1.8 | 1.5 | 1.4 |
| 40–49 | 4867 | 2487 | 2380 | 1.0 | 1.2 | 1.2 | 1.3 | 1.2 | 1.1 |
| 50–59 | 1203 | 610 | 593 | 1.0 | 1.1 | 1.2 | 1.2 | 1.1 | 1.0 |
| 60–69 | 229 | 109 | 120 | 0.9 | 1.1 | 1.2 | 1.2 | 1.2 | 1.2 |
| 70–79 | 50 | 18 | 32 | 0.6 | 0.9 | 0.9 | 0.9 | 1.0 | 0.9 |
| 80 and older | 25 | 8 | 17 | 0.5 | 0.5 | 0.6 | 0.6 | 0.6 | 0.6 |
Data source: HIRA big data open system—Medical statistics by disease/behavior—Disease classification (Level 4 statistics).
Geographically, utilization rates were highest in the Seoul Metropolitan Area and other metropolitan cities, both substantially exceeding provincial rates throughout the study period (Figure 5B). All regions showed increasing trends, with the most pronounced rise observed after May 2022. By institution type, medical clinics consistently accounted for the highest dispensing rates and showed a sharp increase post‐2022, while general hospital rates remained relatively stable (Figure 5A and Table A6).
FIGURE 5.
Monthly ADHD medication dispensing volume by institution type and region, January 2019–May 2023. Panel (A) shows dispensing volume by institution type, expressed as EDU per 1000 persons per month. Medical clinics consistently accounted for the highest dispensing rates, with a marked increase after May 2022. Panel (B) shows dispensing volume by region. The Seoul Metropolitan Area and other metropolitan cities showed substantially higher rates than provinces throughout the study period, with all regions showing increasing trends after 2021. The shaded area indicates the period following strengthened narcotics regulations (after May 2022). *Data Source: Korean Narcotics Information Management System (NIMS).
4. Discussion
This study presents the first comprehensive, population‐level analysis of medical narcotics prescription in South Korea, utilizing four and a half years of data from the NIMS. By capturing data encompassing both reimbursed and non‐reimbursed sectors, our analysis reveals a substantial volume of psychotropic prescribing that has previously remained a “blind spot” in national pharmacovigilance.
A principal finding of this study is the discrepancy between the epidemiology of illicit drug use and the utilization of medical narcotics in South Korea. While the prevalence of illicit drug use remains low by international standards, our NIMS‐based analysis confirms an exceptionally high volume of prescription anorexiants, driven largely by the non‐reimbursed market. This finding aligns with wastewater epidemiology studies that reported disproportionately high levels of phentermine in South Korean cities compared to Western regions [24]. The reliance on NHI claims data in previous pharmacoepidemiologic studies has likely led to a significant underestimation of psychotropic drug exposure in the general population. Our data suggest the magnitude of this gap is substantial: anorexiants, which are largely non‐reimbursed, would be completely invisible in NHI‐based analyses, yet they account for a monthly dispensing volume equivalent to approximately 440 EDUs per 1000 women at primary care clinics. Our results demonstrate that without integrating data from the non‐reimbursed sector, regulatory agencies cannot accurately assess the population‐level risks associated with off‐label prescribing.
The most concerning safety signal identified is the profound gender disparity in anorexiant utilization. Women consumed approximately 440 EDUs per 1000 women per month at the primary care clinic—approximately 15 times the volume dispensed to men. This utilization was heavily concentrated among women aged 30–49 and primarily dispensed by primary clinics. This pattern raises critical public health concerns regarding the appropriateness of prescribing and patient safety. Given that the obesity rate for South Korean women in their 20s to 40s is significantly lower than that of men [25], the massive consumption of anorexiants in this demographic suggests widespread prescribing outside approved indications for aesthetic weight management in the non‐obese population rather than therapeutic management of obesity. This disproportionate exposure of women of childbearing age to anorexiants, which are mostly central nervous system (CNS) stimulants, poses serious risks in population health. Phentermine and phendimetrazine are associated with cardiovascular adverse events and psychiatric disorders, including psychosis and mood instability [13, 15, 16]. Furthermore, the potential for teratogenicity and adverse pregnancy outcomes remains a concern for this specific age group. The persistence of lorcaserin prescriptions after its market withdrawal further underscores the inadequacies of the current safety communication and recall systems in the non‐reimbursed sector in South Korea. While these findings are descriptive in nature, the scale of exposure is exceptional by any international standard and constitutes a compelling pharmacovigilance signal in its own right. The concentration of prescribing in primary care clinics, combined with the absence of reimbursement‐based oversight, points to a regulatory gap in which off‐label anorexiant use has become routinized within a fragmented healthcare system reinforced by intense sociocultural pressures around body image.
Notably, a 2023 government report—one of the few official disclosures on this issue—revealed that 6.5% of women in their 30s and 5.1% of those in their 20s received a prescription for phentermine [26], corroborating the scale of exposure identified in our analysis. This high prevalence aligns with national adverse drug reaction (ADR) data, where phentermine consistently dominates reports of psychiatric side effects [17], the long‐term risks of which are well‐documented [16]. This pattern of widespread prescribing outside approved indications appears to be driven by a confluence of structural factors unique to the South Korean context: fee‐for‐service reimbursement incentives that reward volume over continuity, fragmented primary care that lacks longitudinal patient oversight, and intense sociocultural pressures regarding body image [27].
However, this phenomenon may carry global implications through two distinct pathways. First, the transnational dissemination of South Korean body ideals via digital media is already influencing the health behaviors of international audiences, potentially increasing the demand for pharmacological weight management globally [28, 29]. Second, on a commercial level, these prescriptions are being directly “exported” via medical tourism, where international visitors access these drugs through local clinics [30]. This dual pathway of cultural and commercial transmission elevates the issue from a local regulatory challenge to an international public health concern, particularly for adolescent girls and young women across borders.
In contrast to anorexiants, ADHD medications showed a persistent male predominance across all age groups, consistent with global trends [31, 32]. The sharp increase in dispensing rates after 2021, particularly among school‐aged boys, coincided with the full resumption of in‐person schooling following COVID‐19‐related disruptions, suggesting that deferred evaluations and treatment initiation may have contributed to the observed rise [33]. Unlike anorexiant dispensing—which showed no discernible COVID‐19‐related disruption, likely reflecting the non‐clinical, demand‐driven nature of that market—ADHD medication use appeared sensitive to the school calendar and healthcare access patterns. The temporal correlation with academic semesters further suggests that factors beyond clinical diagnosis, such as academic performance pressures and cognitive enhancement‐seeking, may also contribute to utilization trends [34]. While the medicalization of ADHD is a global phenomenon, the specific patterns observed in South Korea warrant continuous monitoring to distinguish between improved diagnostic access and potential non‐medical stimulant use.
Our findings suggest that in South Korea's non‐reimbursed sector, the clinical gatekeeping function has been substantially undermined. The concentration of high‐volume anorexiant prescribing in primary care clinics—largely driven by cosmetic demand rather than clinical indication, indicates that the prescription requirement may function as an access mechanism rather than a clinical safeguard. This pattern reflects a systemic gap in current drug policy, which has heavily prioritized the “War on Drugs” targeting illicit substances while leaving the non‐reimbursed prescribing market inadequately monitored [8]. Our data reveal that a more pressing public health threat may lie within the legitimate healthcare system, particularly in the non‐reimbursed market. Although the government implemented stricter regulations in 2022, our trend analysis indicates that these measures have had uneven impacts, as evidenced by the steady decline in phentermine prescriptions concurrent with a compensatory rise in phendimetrazine prescriptions (Figure 2), suggesting substitution rather than genuine reduction in anorexiant exposure. To effectively mitigate these risks, an integrated pharmacovigilance system that seamlessly links NHI claims data with NIMS non‐reimbursed data is essential. Regulatory strategies must move beyond simple volume monitoring to focus on indication‐based prescribing audits, particularly for high‐risk agents like phentermine dispensed to vulnerable populations.
This study has several limitations. First, as NIMS data are aggregated to protect privacy, we could not link prescriptions to individual patients to assess longitudinal outcomes or doctor‐shopping behaviors. Second, the study period spans four and a half years (January 2019 to May 2023), which limits the assessment of longer‐term trends and precludes evaluation of outcomes following the 2022 regulatory changes. Third, the absence of diagnostic records in the NIMS database precluded direct verification of prescribing indications; the inference of off‐label use is therefore based on demographic patterns and population‐level obesity prevalence data rather than confirmed diagnoses. Fourth, the use of unit‐based standardization instead of weight‐based DDDs may have introduced estimation errors, although it provides a consistent metric for trend analysis. Fifth, we lacked data on socioeconomic status, limiting our ability to assess health equity implications. Future research should prioritize individual‐level linkage studies to evaluate the safety outcomes associated with off‐label use directly.
This study provides the first population‐level analysis of medical narcotics utilization in South Korea's non‐reimbursed sector, revealing a substantial volume of psychotropic prescribing that has remained invisible to standard pharmacovigilance systems. The disproportionate exposure of young women to anorexiants, concentrated in primary care clinics and largely outside approved indications, represents a compelling safety signal requiring urgent regulatory attention. The steady rise in ADHD medication dispensing, particularly among school‐aged children, warrants continued monitoring to distinguish expanding diagnostic access from potential non‐medical use. Addressing these risks requires not only the development of an integrated data infrastructure linking NIMS with NHI records but also the establishment of professional accountability mechanisms for prescribing outside the reimbursement system, where clinical oversight is currently most limited and the potential for patient harm is greatest.
Author Contributions
Conceptualization: Jin‐Hwan Kim, Saerom Kim. Data curation: Jin‐Hwan Kim, Saerom Kim. Formal analysis: Jin‐Hwan Kim. Methodology: Jin‐Hwan Kim. Writing – original draft: Jin‐Hwan Kim, Saerom Kim. Writing – review and editing: Jin‐Hwan Kim, Jonghun Kim, Saerom Kim.
Funding
The work was supported by the 2024 Inje University research grant (20240074). The funder had no role in study design, data collection, analysis, publication decision, or manuscript preparation.
Ethics Statement
This study was approved by the Institutional Review Board of the Korean Women's Development Institute (IRB No. 2023‐01‐07). All data were anonymized before analysis and did not include any identifiable personal information.
Conflicts of Interest
The authors declare no conflicts of interest.
Supporting information
Table A1 Information included in each dataset.
Table A2 Detailed subcategories on the medical narcotics.
Table A3 Monthly prescription volume, prescription cases, volume per case for anorexiants.
Table A4 Monthly prescription volume for anorexiants by drug ingredients.
Table A5 Number of people diagnosed with ADHD (2022) and gender ratio in ADHD medications' prescription.
Table A6 Monthly prescription volume, prescription cases, volume per case for ADHD medications.
Acknowledgements
The data used in this study were obtained from the 2023 Specific Gender Impact Assessment commissioned by the Ministry of Gender Equality and Family of Korea.
Data Availability Statement
Narcotics information management system (NIMS) data can be available on a yearly basis through the data application process (https://data.nims.or.kr).
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Table A1 Information included in each dataset.
Table A2 Detailed subcategories on the medical narcotics.
Table A3 Monthly prescription volume, prescription cases, volume per case for anorexiants.
Table A4 Monthly prescription volume for anorexiants by drug ingredients.
Table A5 Number of people diagnosed with ADHD (2022) and gender ratio in ADHD medications' prescription.
Table A6 Monthly prescription volume, prescription cases, volume per case for ADHD medications.
Data Availability Statement
Narcotics information management system (NIMS) data can be available on a yearly basis through the data application process (https://data.nims.or.kr).