Background Warning labels on cigarette packages are an important venue for information about the hazards of smoking. The 2009 US Family Smoking Prevention and Tobacco Control Act mandated replacing the current text-only labels with graphic warning labels. However, labels proposed by the Food and Drug Administration (FDA) were challenged in court by the tobacco companies, who argued successfully that the proposed labels needlessly encroached on their right to free speech, in part because they included images of high emotional salience that indiscriminately frightened rather than informed consumers.

Methods We used functional MRI to examine the effects of graphic warning labels’ emotional salience on smokers’ brain activity and cognition. Twenty-four smokers viewed a random sequence of blocks of graphic warning labels that have been rated high or low on an ‘emotional reaction’ scale in previous research.

Results We found that labels rated high on emotional reaction were better remembered, associated with reduction in the urge to smoke, and produced greater brain response in the amygdala, hippocampi, inferior frontal gyri and the insulae.

Conclusions Recognition memory and craving are, respectively, correlates of effectiveness of addiction-related public health communications and interventions, and amygdala activation facilitates the encoding of emotional memories. Thus, our results suggest that emotional reaction to graphic warning labels contributes to their public health impact and may be an integral part of the neural mechanisms underlying their effectiveness. Given the urgency of the debate about the constitutional risks and public health benefits of graphic warning labels, these preliminary findings warrant consideration while longitudinal clinical studies are underway.