The toll of tobacco: smoking-attributable health spending in South Korea, 2014-2024. National claims evidence for cost recovery.

Background: South Korean policymakers are weighing tobacco control and financing options amid rising health-care costs. This study estimates the direct medical expenditure attributable to active and second-hand smoking (SHS) using Korea's National Health Insurance Service (NHIS) claims data (2014-2024) and quantifies the fiscal burden borne by the public insurer vs. households. Methods: Annual NHIS claims data for all beneficiaries for the period 2014-2024 were linked with disease-specific Population Attributable Fractions (PAFs) derived from the Global Burden of Disease (GBD) study. Costs were stratified by sex, age, income group, and payer (NHIS vs. out-of-pocket) and expressed in 2024 US dollars. Findings: Smoking-attributable medical spending totaled USD 29.86 billion over the period from 2014 to 2024. In 2024 alone, costs reached USD 3.38 billion, representing 19.7% of expenditure for the analyzed conditions and approximately 4.0% of national health expenditure. The fiscal burden was shared between the public insurers (82.5%) and households (17.5% out-of-pocket). Costs were highest among men (80.1%) and adults aged 50-79 (80.7%), reflecting a "lagged epidemic" driven by historical exposure. The top 10 conditions accounted for 88.2% of total smoking-attributable spending, with cancers absorbing 35.2% and cardiometabolic diseases absorbing 53.1%. Costs for men were driven by active smoking (∼90%), while costs for women were largely attributable to SHS, which accounted for 48% of their total costs compared to 9% for men. Interpretation: Past smoking choices of South Koreans have left a legacy of current medical costs that many non-smokers are now facing. Women and men who never chose to smoke are succumbing to illness due to SHS which accounts for 16.5% of overall costs. New generations of workers must bear these costs through taxation and premiums to finance South Korea's health care system. The current decline in smoking prevalence is insufficient to arrest the rising financial momentum of historical exposure. These findings provide evidence for a way out of the cycle by correcting prices of tobacco to include the social costs. A polluter-pays framework would recover public health expenditures and deter new generations from imposing consequences of their personal choices on others. Funding: None.