Impact of different health warning label and reduced exposure messages in IQOS ads on perceptions among US and Israeli adults

Heated tobacco products (HTPs; e.g., IQOS) are advertised as safer than cigarettes or an alternative, yet required health warning labels (HWLS) in many countries, including the US and Israel, do not consider whether HTP ads undermine HWLs, particularly those that do not explicitly address HTPs. In 2021, a randomized 4 x 3 factorial experiment among 2,222 US and Israeli adults examined IQOS ads with differing: 1) HWLs (i.e., smoking risks, prompt to quit, HTP-specific, control); and 2) ad messages (i.e., slight distancing: "cigarette-like satisfaction, no odor", clear distancing: "looking for an alternative?", control). Outcomes were perceived relative harm (vs cigarettes), exposure to harmful chemicals, and disease risk and likelihood of trying or suggesting IQOS to smokers. Ordinal logistic regression was used, adjusted for covariates. One HWL effect was found: risk (vs control) increased perceived relative harm (aOR = 1.21, CI = 1.03-1.41) and exposure (aOR = 1.22, CI = 1.04-1.42) and decreased likelihood of trying IQOS (aOR = 0.82, CI = 0.69-0.97). Both slight and clear distancing ads (vs control) decreased perceived harm (aOR = 0.85, CI = 0.75-0.97; aOR = 0.63, CI = 0.55-0.72, respectively) and increased likelihood of suggesting IQOS to smokers (aOR = 1.23, CI = 1.07-1.41; aOR = 1.28, CI = 1.11-1.47); slight distancing decreased perceived disease risk (aOR = 0.85, CI = 0.75-0.97); and clear distancing decreased perceived exposure (aOR = 0.73, CI = 0.64-0.83). Clear (vs slight) distancing decreased perceived relative harm (aOR = 0.74, CI = 0.65-0.85) and exposure (aOR = 0.82, CI = 0.71-0.93). One interaction effect was found: the quitting HWL and clear distancing led to particularly low perceived relative harm (aOR = 0.63, CI = 0.43-0.93). Regulatory agencies must monitor the impacts of advertising, including reduced risk/exposure messaging on perceptions of HWL messages, to inform future regulatory efforts.