Delphi study among international expert panel to develop waterpipe-specific health warning labels.

This study is the first to systematically develop and evaluate potential WP-specific HWLs based on the scientific evidence about WP's harmful effects, scientific understanding of HWL for cigarettes and the opinions of experts in WP science, tobacco control and health communication. The final selected HWLs can be adapted based on the context and policy landscape of the target country and can be further fine-tuned based on feedback from WP smokers and non-smokers.