Used in photodynamic therapy (PDT) for the treatment of skin conditions such as actinic keratosis and certain types of non-melanoma skin cancers. It serves as a prodrug that is converted in the skin cells into protoporphyrin IX (PpIX), a photosensitizing agent. When exposed to specific wavelengths of light, PpIX produces reactive oxygen species that selectively destroy abnormal or cancerous cells. Its topical application allows targeted treatment with minimal systemic absorption, reducing side effects. Also investigated for use in fluorescence diagnosis due to the natural fluorescence of accumulated PpIX in diseased tissue.