Effects of photobiomodulation in asthma: an integrative and critical review of preclinical and clinical evidence.

Asthma is a chronic inflammatory disease of the airways, affecting approximately 300 million people worldwide and generating a high socioeconomic burden. Despite advances in pharmacological therapies, therapeutic gaps remain, especially in corticosteroid-refractory phenotypes. Photobiomodulation (PBM) has emerged as a potential adjuvant due to its anti-inflammatory, antioxidant, and immunomodulatory effects. This integrative review critically analyzed experimental, clinical, and in vitro studies published between 2017 and 2025. Nine studies met the inclusion criteria: seven in animals, one clinical trial, and one in vitro. In animal models, PBM consistently reduced pulmonary inflammation, airway remodeling, and Th2 cytokines (IL-4, IL-5, IL-13), while increasing IL-10. The in vitro study confirmed these effects and demonstrated superiority over dexamethasone in corticosteroid-resistant markers such as IL-21 and IL-23. However, the only randomized trial in humans, limited by a small sample size and single-session design, found no significant improvements in muscle function or systemic inflammation. Taken together, the evidence supports the biological plausibility of PBM but highlights the gap between experimental results and clinical application. Future trials should adopt standardized dosimetric parameters, longer interventions, and clinically relevant outcomes, including lung function, exacerbation frequency, and corticosteroid dependence, to clarify the therapeutic role of PBM in asthma.