A recent paper reports a case of esomeprazole-induced drug rash with eosinophilia and systemic symptoms (DRESS) syndrome, occurring 20 days after the onset of treatment (12). In this case patch tests were positive to esomeprazole, with further demonstration of cross-reactivity to omeprazole and pantoprazole, but not to rabeprazole. In this respect, previous studies have already focused on the cross-reactivity between omeprazole and pantoprazole, which have similar chemical structures, and the lack of this cross-reaction between omeprazole (or pantoprazole) and rabeprazole (or lansoprazole) (13,14).