The Effect of Low-Level Light Therapy on Capsaicin-Induced Peripheral and Central Sensitization in Healthy Volunteers: A Double-Blinded, Randomized, Sham-Controlled Trial

Abstract Introduction Several clinical trials have demonstrated that low-level light therapy (LLLT), a method of photobiomodulation, is an effective analgetic treatment. However, the mechanism of action has not yet been finally clarified. In particular, unanswered questions include whether it only affects peripheral or whether it also affects the spinal or supraspinal level. This study aimed to evaluate the effect of low-level light therapy on primary and secondary hyperalgesia in a human pain model. Methods This study was planned as a randomized, sham-controlled, and double-blinded trial with repeated measures within subject design. Capsaicin was applied on both forearms of ten healthy volunteers to induce peripheral and central sensitization. One forearm was treated with low-level light therapy; the other served as sham control. Results Low-level light therapy significantly increased the mechanical pain threshold, heat pain threshold, and decreased pain intensity. Conclusions Our data indicate that low-level light therapy is effective at reducing the heat and mechanical pain threshold in a human pain model, pointing to a significant modulating effect on peripheral and central sensitization. These effects—especially in the absence of reported side effects—make low-level light therapy a promising tool in pain management. The application of low-level light therapy to treat chronic pain should be considered for further clinical trials.

Abstract licence: CC BY-NC

• Multimodal non-invasive non-pharmacological therapies for chronic pain: mechanisms and progress · 2023

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