IntroductionAs part of several measures to inform consumers about the health risks of alcohol, the Irish Government signed into law the Public Health (Alcohol) Act 2018, with Section 13 requiring the implementation of multiple health warnings in all alcohol ads. Although health warnings on product labels have been subject to intensive political discussion and academic research, health warnings in alcohol ads have received little attention.MethodsA between‐subject factorial survey experiment was conducted with a convenience sample of adults in Ireland (n = 932) to compare single‐text, multiple‐text and shocking image‐and‐text health warnings displayed on two types of static alcohol ads—an ad with social imagery featuring people drinking alcohol and an ad featuring only the alcohol product. Believability of health warnings, negative emotions, perceived risks of alcohol use and self‐efficacy to drink less were measured after viewing each alcohol ad with or without health warnings.ResultsSingle‐text health warnings, with and without shocking imagery, were more effective in increasing negative emotions than multiple‐text health warnings (p ≤ 0.001), whereas multiple‐text warnings were found to be more believable than single‐text warnings (p ≤ 0.001). No significant effects were found on perceived risks of alcohol use and self‐efficacy to drink less (p > 0.05). The warnings did not differ across demographic groups and the type of alcohol ads on all outcomes (p > 0.05).Discussions and ConclusionsA single health warning emphasising cancer risk could be a useful starting point for policymakers when implementing health warnings in alcohol ads.