Mounjaro at a third of Korea's price draws Koreans to Japanese clinics

Customs logged about 629 detections a month through August ^[15], against one every three months across 2024 ^[16]. The rise came while the service was stepping up enforcement and tightening inspections at the border ^[7]. More bags carrying the drug and more bags being opened both raise the count, so the jump overstates the growth in traffic by an amount these figures cannot isolate.

Against the home market the detected flow is small. Prescription data for the 10 months to May works out to about 150,000 Mounjaro prescriptions a month in Korea ^[17], and monthly detections equal roughly 0.4% of that ^[18]. The two windows differ, one bag can hold several months of supply, and undetected carries never reach the count, so the real share is higher.

Korean prices are set clinic by clinic. Obesity prescriptions fall outside national health insurance, so medical institutions charge what they choose ^[9]. The domestic range at the starting dose is 70,000 won wide ^[19], a little over a third of the smallest gap to Japan, 195,000 won ^{[14] [20]}. A price-sensitive patient in Seoul can find the cheaper clinic before booking a flight. If competition were pressing on Korean prices, the spread between Korean clinics would narrow first. Seoul Economic Daily, which carried the Nikkei report, attributes the high level to strong demand for weight loss and cosmetic use combined with wide price differences between hospitals ^[10].

One way this resolves is a Korean price cut toward the bottom of the range, or below it, to keep patients at home. Another leaves prices where clinics put them and the burden on customs, with each buyer weighing the saving against flights, hotels and the chance of a bag being opened. The third runs through Tokyo. Nikkei reported concern that continued buying by Koreans could leave Japanese patients without adequate supply ^[12]. Japan's health ministry has already urged medical institutions to make sure the drug reaches the patients who need it ^[13].

I think the border and Tokyo settle this before Korean clinics do. The visible response in Korea so far is customs work ^[7]. Bringing obesity prescriptions under national insurance would set a public price, and the reporting does not mention any plan to do it. The counter-case is that the 5,030 detections ^[4] are a small, visible fraction of a habit spreading online, where users post that Japan is far cheaper even after round-trip airfare and lodging ^[3]. If enough patients follow those posts, clinics will have to cut. A fall in Korean clinic prices toward or below 280,000 won a month ^[2] would show that case is right.