Disclosed herein are compositions comprising photosensitizing agents, in particular lemuteporfin or verteporfin, and their use in photo- dynamic therapy for the treatment of dermatological conditions. In one embodiment the composition comprises a photosensitizing component and an excipient component, such as benzyl alcohol, DGME or isopropyl alcohol, in a solution wherein the concentration of the photosensitizer in the solution is supersaturating.