 Photofrin registered was first approved in the 1990s as a sensitizer for photodynamic therapy, PDT, treatment of cancer and skin diseases. Since then, various dye sensitizers have been developed and approved for PDT, with porphyrinoid derivatives being the most successful in producing requisite singlet oxygen. Other porphyrinoid compounds that have received FDA approval include benzoporphurin derivative monoacid ring A, BPDMA, metatetra, hydroxyphenyl, chlorine, MTHPC, anispartylchlorine E6, NPE6, and precursors to endogenous protoporphurin 9, PPIX1, 5-aminolebulinic acid, ALA, methylaminolebulinate, MAL, hexaminolebulinate, HAL. While no non-porphyrin sensitizer has been approved for PDT applications, anthroquinone, phenotheazine, xanthine, cyanine, and curcuminoid sensitizers are under consideration and some are being evaluated in clinical trials. This article was authored by Harold S. Freeman and Alexander B. Ormond. We are article.tv, links in the description below.