Health warning labels on cannabis products. What is the best design?

Health warning label on cannabis products has been recently studied, and with the latest trends of regulation around the world, there is a need to determine the most effective ways to apply this strategy. The current study aimed to examine the effects of different health warning label designs (pictorial vs text-only, background color, warning themes) on cannabis products.

An online experiment study (N=533) was carried out in Colombia with a between-subject design. Participants were randomly assigned to five package conditions: without warning, text-only white warning, text-only yellow warning, pictorial white warning, and pictorial yellow warning. Participants performed an attention task and rated each of the stimuli based on product appeal, perceived addictiveness, harm perception, and interest in trying cannabis products.

Pictorial health warnings were generally the most effective. Especially, pictorial health warnings with a yellow background were found to decrease product appeal and interest in trying cannabis products, as well as increase harm perception compared to other designs. The most effective warning themes were mental health, smoke toxicity, aesthetic implications, and traffic accidents.

The current study provides empirical evidence on the effectiveness of different designs of cannabis health warnings. Our results suggest that graphic yellow warnings are the most effective in communicating the risks of cannabis use.