Background Although Food and Drug Administration (FDA)-mandated waterpipe tobacco warnings were not required until August 2018, some waterpipe tobacco packaging (WTP) sold in the USA, contained warnings prior to this date. We examined the prevalence of WTP warning exposure and whether exposure influenced risk perceptions or use among young adult (aged 18–24 years) current waterpipe users.

Methods We used data from waves 1 (2013–2014) and 2 (2014–2015) of the Population Assessment of Tobacco and Health Study, a nationally representative longitudinal study of US adults and youth. We conducted logistic regression analyses to identify factors associated with wave 1 warning exposure, and whether wave 1 WTP warning exposure predicted wave 2 relative risk perceptions and waterpipe use.

Results More than one-third of our sample (35.9%, 95% CI 33.5 to 38.4) reported past-month WTP warning exposure. Exposure was higher among males (adjusted OR (AOR)=1.34, 95% CI 1.04 to 1.72), those who usually do not share the waterpipe (AOR=3.10, 95% CI 1.45 to 6.60), those who purchased waterpipe tobacco (AOR=1.73, 95% CI 1.28 to 2.34), and those with a regular brand (AOR=1.84, 95% CI 1.26 to 2.68). Those exposed to WTP warnings at wave 1 were more likely than those not exposed to perceive waterpipe tobacco to be as or more harmful than cigarettes at wave 2 (AOR=1.35, 95% CI 1.02 to 1.78). There was no association between wave 1 WTP exposure and wave 2 waterpipe use.

Conclusions More than one-third of US young adult current waterpipe users reported WTP warning exposure prior to FDA-mandated warning implementation. Findings suggest the mandated warning may result in high exposure among users; it will be critical to assess exposure’s impact on risk perceptions and behaviour after FDA-mandated warnings are implemented.