LAUSR

Pictorial health warning label (PHWL) is an effective risk communication measure among cigarette smokers. However, there is a lack of knowledge regarding the effect of PHWL on low- and high-frequency waterpipe (WP) smokers. This study examined the effects of PHWL on puffing behavior, subjective experiences, and toxicant exposures among low- and high-frequency WP smokers in the United States (US). Sixty current (past-month) WP smokers (low-frequency; n = 30 and high-frequency; n = 30) completed two 45-min ad libitum WP smoking sessions in a cross-over design study (WP with no-PHWL vs. WP with PHWL). We compared the mean differences of puff topography, expired carbon monoxide (eCO), plasma nicotine concentration, and subjective experiences between the two smoking groups. Mean age of low-frequency smokers was 21.5 years and high-frequency smokers was 21.3 years. Compared to high-frequency, low-frequency smokers had significant reduction in average total smoking time [mean difference (SD) =  −7.6 (10.2) min vs. −2.6 (6.7) min, p = 0.03] and number of puffs [mean difference (SD) =  −33.37 (70.7) vs. −0.70 (29.2), p = 0.02] following exposure to PHWL compared to no-PHWL condition. Post-session subjective experiences were lower among high-frequency smokers compared to low-frequency smokers following smoking WP with PHWL compared to the no-PHWL session (puff liking −1.2 vs. −0.5; puff satisfaction −1.0 vs. −0.3; craving reduction −0.5 vs. 1.2) (p < 0.05 for all). Our findings indicate that placing PHWL on the WP device may be a promising strategy with differential effectiveness among WP smokers: low-frequency (reduce puffing behaviors) and high-frequency (reduce smoking experience).