Photobiomodulation: A review of the molecular evidence for low level light therapy

J Plast Reconstr Aesthet Surg. 2021 May;74(5):1050-1060. doi: 10.1016/j.bjps.2020.12.059. Epub 2020 Dec 27.


Light energy is harnessed for therapeutic use in a number of ways, most recently by way of photobiomodulation (PBM). This phenomenon is a cascade of physiological events induced by the nonthermal exposure of tissue to light at the near infrared end of the visible spectrum. Therapeutic PBM has become a highly commercialized interest, marketed for everything from facial rejuvenation to fat loss, and diode-based devices are popular in both the clinic setting and for use at home. The lack of regulatory standards makes it difficult to draw clear conclusions about efficacy and safety but it is crucial that we understand the theoretical basis for PBM, so that we can engage in an honest dialogue with our patients and design better clinical studies to put claims of efficacy to the test. This article presents a summary of the science of PBM and examines the differences between laser light, on which much of the preclinical evidence is based and light from diodes, which are typically used in a clinical setting.

Keywords: Laser; Light emitting diode; Low level light therapy; Oxidative stress; Photobiomodulation; Skin rejuvenation.

Publication types

  • Review

MeSH terms

  • Animals
  • Cell Proliferation / radiation effects
  • Dose-Response Relationship, Radiation
  • Humans
  • Lasers, Semiconductor / therapeutic use*
  • Low-Level Light Therapy / methods*
  • Mesenchymal Stem Cells / radiation effects
  • Oxidative Stress
  • Rejuvenation*