A Retrospective Study of Multiple Sequential Light and Laser Sources to Activate Aminolevulinic Acid in the Treatment of Acne Vulgaris. Reports of the sequential use of multiple light and laser sources for topical 5-aminolevulinic acid (ALA) activation in photodynamic therapy (PDT) of inflammatory acne vulgaris are lacking. The authors sought to retrospectively compare field-directed ALA-PDT with blue light only, blue light + pulsed dye laser (PDL), blue light + intense pulsed light (IPL), blue light + PDL + IPL, or blue light + red light + PDL + IPL for inflammatory acne of the face or upper trunk. Results showed a trend toward greater patient-reported improvement with comparable tolerability using multiple, sequential light sources in ALA-PDT for acne vulgaris, albeit not statistically significant. The addition of red light, however, did not improve outcomes. The disparate numbers of patients between treatment arms and high potential for recall bias limit this single-center retrospective study.