A widening gap in obesity-drug prices between South Korea and Japan is creating a new pressure point for the fast-growing GLP-1 market, as Korean consumers increasingly turn to overseas sources for cheaper supplies. For U.S. drugmakers and investors, the surge highlights how pricing, reimbursement rules and cross-border access could shape the next phase of demand for blockbuster weight-loss treatments.
South Korean customs authorities recorded 4,155 cases of illegally imported obesity drugs including Wegovy and Mounjaro during the first six months of 2026, more than 3.5 times the 1,189 cases recorded during all of 2025, according to data released September 24.
The increase has been steep since the drugs entered the Korean market. Customs recorded only four cases in 2024, followed by 1,189 in 2025 and 4,155 in the first half of 2026, bringing the cumulative total to 5,348 cases.
The surge is particularly striking compared with legal imports. Only 596 shipments were officially cleared through commercial importers during the same period—14 in 2024, 191 in 2025 and 391 during the first half of 2026.
International mail has become the main channel for illegal purchases. Customs recorded 3,489 cases involving international postal shipments in the first half of 2026, accounting for 84.8% of all cases accumulated since 2024. Travelers accounted for another 656 cases during the first six months of this year.
The primary incentive is price.
A four-week supply of 2.5-milligram Mounjaro costs about $200 at the cheapest clinics in South Korea, compared with roughly $51 in Japan. At the 10-milligram dose, the price is about $370 in South Korea versus $202 in Japan.
The disparity reflects differences in the two countries’ health-care and drug-pricing systems. In Japan, Mounjaro is covered by the national health-insurance system for Type 2 diabetes and is subject to government price controls. Competition among online medical clinics has added further pressure on prices.
South Korea classifies obesity treatment as a noncovered medical service, allowing individual clinics to set prices. A weaker yen has also made purchases in Japan more attractive to Korean consumers, while demand for higher-dose products that can be difficult to obtain domestically has added another incentive.
The phenomenon is beginning to reshape the market beyond traditional pharmacies and clinics. Korean consumers are increasingly using overseas websites and international mail to obtain the drugs, while some Japanese clinics have begun targeting Korean customers with Korean-language information, KakaoTalk consultations and interpretation services.
Online communities are also circulating advice on how to avoid customs inspections, including reports from travelers who carried Mounjaro back from Japan in personal luggage.
South Korea generally allows travelers to bring in up to six units or a three-month supply of ordinary medicines for personal use. Wegovy and Mounjaro are treated differently: The Ministry of Food and Drug Safety classifies them as hazardous medicines, meaning they cannot be imported without a required exemption recommendation.
Customs authorities said they are enforcing the restriction regardless of quantity and are holding and destroying intercepted shipments. Unauthorized imports can also lead to penalties under South Korea’s Customs Act.
The enforcement challenge is likely to grow as demand for GLP-1 treatments expands. Customs officials cannot inspect every traveler’s luggage, and confiscation and destruction may do little to eliminate the underlying financial incentive created by large international price differences.
For drugmakers and investors, the Korean market illustrates a broader issue facing the global obesity-drug industry. As GLP-1 treatments move into mass-market use, differences in reimbursement, pricing and availability between countries can influence not only legitimate sales but also where consumers choose to obtain the drugs.
The Korean case also highlights the potential tension between expanding access to obesity treatments and maintaining tightly controlled distribution channels. If demand continues to rise faster than affordable domestic access, cross-border purchasing could remain an attractive alternative for consumers despite tighter customs enforcement.
Experts say South Korea may need to pair stronger border enforcement with policies that narrow international price disparities and reduce patients’ out-of-pocket costs if it wants to curb the rapidly expanding illicit market.
