Used in photochemotherapy (PUVA therapy) for skin disorders like psoriasis, vitiligo, and eczema. When activated by ultraviolet A (UVA) light, it binds to DNA and inhibits rapid cell division, making it effective in reducing psoriatic plaques. In vitiligo, it helps repigment skin by stimulating melanocytes. Also used in research for its DNA-interacting properties and in some cosmetic applications for controlled skin pigmentation. Additionally, studied for antimicrobial and antiviral effects, particularly in inactivating viruses in blood products or plasma using UVA light to prevent infections in transfusions. Requires careful dosing due to risk of skin damage and increased photosensitivity.