Association of Photodynamic Therapy and Photobiomodulation As a Promising Treatment of Herpes Labialis: A Systematic Review

Background: This systematic review aims to analyze the effectiveness of the association of photodynamic therapy (PDT) and photobiomodulation (PBM) in the treatment of recurrent herpes labialis and to analyze the very many variables of parameters applied, number of sessions, photosensitizer concentration, and the timing of the intervention to offer clinicians an indication of the most likely optimal techniques and parameters required to achieve clinical success.Methods: This study was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses PRISMA Checklist and registered at the International Prospective Register of Systematic Reviews (PROSPERO). We searched and identified articles of the subsequent bibliographic databases: PubMed and Cochrane.Results: Since there are no clinical trials regarding the association of PDT and PBM in the treatment of herpes labialis, we only included case reports in our review. All studies used methylene blue solution as the photosensitizer and the laser (diode laser or low-power laser) with a wavelength of 660 nm as the light source. Power output, power density, number of irradiation points, number of PBM sessions, and irradiation duration varied between the included studies. Despite the diversity in parameters between studies, all case reports showed good results regarding relieving symptoms, accelerating healing, as well as reducing the incidence of recurrence without side effects.Conclusions: The association of PDT in the vesicular phase and PBM in the crust phase can be considered a promising solution for recurrent labial herpes. Despite the many successful cases reported, establishing an effective clinical protocol for the treatment of herpes labialis using PDT followed by PBM will only be possible through double-blind placebo studies that would elucidate the exact action of this treatment modality, the appropriate irradiation parameters for both therapies, optimal timing, and number of PBM sessions following PDT.This review has been registered at the International Prospective Register of Systematic Reviews (PROSPERO) under number CRD42021290757.