Atopic dermatitis and psoriasis are two diseases that are thought to be distinct from each other, both clinically as well as pathogenetically. Substantial progress has been made in their treatment through the introduction of targeted therapies, blocking key steps in the respective pathogenetic pathways. Interestingly, introduction of a specific therapy for one of these diseases can occasionally trigger onset of the other. This observation helps to better understand the pathophysiology of both diseases and directly impacts their management.