In Reply We would like to thank Drs Langendonk and Wilson for their insightful comments that highlight the challenges of diagnosis and treatment of erythropoietic protoporphyria (EPP). We agree that data from the 3 cases may not be generalized until larger-scale rigorous clinical trials can be conducted. Nevertheless, the dramatic and rapid clinical improvements our patients experienced cannot be ignored. The overwhelming positive responses from the international EPP community have led us to believe that cimetidine has the potential to be a safe and effective addition to the management of EPP and warrants further study.