Objective:
Health warnings are an effective strategy for communicating information on smoking-related health harms, encouraging smoking cessation, and preventing smoking initiation. This study is the first to examine the effectiveness of existing text-only health warnings, identify key indicators of health warning effectiveness, and assess support for pictorial warnings in Japan.

Methods:
Data are from the 2018 International Tobacco Control (ITC) Japan Survey, a web-based cohort survey of adult cigarette smokers (n=3306), dual users of cigarettes/heated tobacco products (n=555), and non-cigarette smokers (n=823). Six key indicators of health warning effectiveness: salience (noticing, reading); cognitive responses (thinking about harms, quitting); and behavioral responses (forgoing cigarette, avoiding warnings). Respondents were asked whether they supported pictorial warnings on cigarette packs. Weighted multivariable logistic regression models were used to assess predictors of health warning effectiveness and support for pictorial warnings by demographics, and smoking status.

Results:
15.6% of respondents noticed health warnings, and 7.9% read or looked closely at warnings. 10.3% of respondents said that the warnings stopped them from having a cigarette, and 7.2% avoided warnings. Although 27.5% of respondents said the warnings made them think about health risks of smoking, only 2.7% said the warnings made them more likely to quit. There were few differences by smoking status across most indicators of warning effectiveness, with the exception of higher noticing of warnings among cigarette smokers (30.0%) vs dual users (20.6%) and non-cigarette smokers (11.7%). A majority of respondents (57.6%) support pictorial warnings, with lower support among cigarette smokers (29.4%) vs dual users (36.2%) and non-cigarette smokers (64.2%).

Conclusions:
Japan’s existing text-only warnings are ineffective across all key indicators of warning salience, and behavioral and cognitive responses to warnings. While there is majority support for pictorial warnings in Japan, it is still well below the level of support found in other countries.