BACKGROUND AND OBJECTIVE: Photodynamic therapy (PDT) is associated with erythema and edema. Photobiomodulation (PBM) therapy may stimulate the skin recovery process. We investigated the potential of PBM to reduce PDT-induced skin reactions.

STUDY DESIGN AND METHODS: Healthy volunteers (n = 20) were randomized to receive left- or right side PBM (near-infrared 839/595 nm) or placebo-PBM (595 nm) on their buttocks. Corresponding test areas were exposed to standardized PDT reactions, using ablative fractional laser-assisted PDT (AFXL-PDT) with methyl-aminolevulinate (MAL) incubated for 30, 90, and 180 minutes before red-light illumination. Each buttock received PBM and placebo-PBM for five consecutive days, starting one day before PDT interventions. Follow-up visits were performed 4 and 11 days after PDT. Outcome measure included blinded, observer-assessed skin reactions, substantiated by objectively measured erythema and pigment percentages and skin temperatures.

RESULTS: PDT interventions induced a standardized range of erythema and edema in all subjects. Skin reactions were clinically unaffected by PBM throughout the active treatment period and at all subsequent follow-up visits (PBM vs. placebo-PBM, P = 1.000). Clinical results were supported by similar erythema intensities and skin temperatures in PBM and placebo-PBM treated skin: median erythema 28.1% versus 30.3% (AFXL-PDT with 30 minutes MAL-incubation), 36.1% versus 35.2% (90 minutes MAL-incubation) and 39.4% versus 40.9% (180 minutes MAL-incubation) (Day 4, P > 0.05). No differences in clinical hyperpigmentation or pigment percentages were observed between corresponding test areas in any subject on the final 11-day follow-up.

CONCLUSION: Under the current study conditions, PDT-induced skin reactions were unaffected by PBM. Lasers Surg. Med. 49:810-818, 2017. © 2017 Wiley Periodicals, Inc.