Photobiomodulation in chronic pain: a systematic review of randomized clinical trials

Introduction: Photobiomodulation (PBM) stands out as a promising therapeutic alternative for the management of chronic pain, but there is still controversy regarding its efficacy and safety, given the diversity of protocols and populations evaluated. Objectives: To critically review the available literature on the use of PBM in adults with chronic pain conditions, synthesizing the evidence on analgesic and functional effects, impact on quality of life, and safety profile. Methods: A systematic search was conducted in PubMed, Embase, Scopus, LILACS, and MEDLINE, including articles published between September 2015 and September 2025. Randomized clinical trials that compared PBM protocols to placebo, sham, or conventional care were selected. The outcomes investigated included pain intensity (primary), function, quality of life, and occurrence of adverse events (secondary). Results: Fourteen studies were included, covering populations with fibromyalgia, peripheral neuropathies, orofacial pain, and musculoskeletal pain. Most trials demonstrated significant pain reduction with PBM, particularly in fibromyalgia and neuropathy. In some studies, functional gains and improved quality of life were observed. The incidence of adverse events was low, reinforcing the method’s safety, although the heterogeneity of technical parameters compromises the standardization of results. Conclusion: PBM has analgesic potential and a safe profile for managing chronic pain, especially in cases difficult to control with conventional therapies. However, the variability of clinical parameters and limited follow-up still hinder more comprehensive recommendations. Additional multicenter studies with standardized protocols are needed to consolidate clinical guidelines. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/view/CRD420251140711, Identifier: CRD420251140711.