In this naturalistic trial, parents’ purchases of sugary drinks for their children were shown to be reduced due to pictorial warnings. Warnings on sugary drinks are a promising policy approach to decrease sugary drink purchasing in the US.

• In the US, children consume more than the recommended levels of sugary drinks, elevating their risk of various chronic diseases, including type 2 diabetes and heart disease.

• In a randomized trial, parents of children aged 2 to 12 years (n = 325) were included, and participants were randomly assigned to a pictorial warnings arm (sugary drinks displayed pictorial health warnings regarding type 2 diabetes and heart damage) or a control arm (sugary drinks displayed a barcode label).

• Participants were asked to complete a shopping task in a naturalistic store laboratory, where sugary drinks had the assigned label, and completed a survey.

• A 17% absolute decrease in the purchasing of sugary drinks resulted from exposure to pictorial warning labels on sugary drinks, vs exposure to the barcode control label.

• Pictorial warnings also resulted in lower intents to serve sugary drinks to their child, feeling more in control of healthy eating decisions, greater thinking about the harms of sugary drinks, stronger negative emotional reactions, greater anticipated social interactions, lower perceived healthfulness of sugary drinks for their child, and greater injunctive norms to limit sugary drinks for their child.