A method of photodynamic therapy is described that includes administering a therapeutically effective amount of a photosensitizer to an area of tissue such as the skin of a subject, delivering a first photoirradiation with light having a wavelength suitable to activate the photosensitizer to the area of skin, allowing a sufficient interval of time to pass for an effective amount of the photosensitizer to penetrate the tissue, and then delivering a second photoirradiation with light having a wavelength suitable to activate the photosensitizer to provide a therapeutic effect. Use of multiple photoirradiations increases the speed with which the photosensitizer can penetrate the tissue to reach the area where the source of the disease is present.
