Red Light Therapy for Nerve Injury: Scientific Evidence

Comparing photobiomodulation (PBM) against no light treatment after nerve-transfer surgery, a 2020 randomized controlled trial examined recovery from an injury to the nerve network in the shoulder. 14 patients in Malaysia who had undergone surgery to reroute a working nerve and restore elbow bending were split into 2 equal groups, with 1 group receiving 808 nm light at 50 mW, 50 mW/cm², and 4 J/cm² in contact with the muscle at the front of the upper arm for 30 seconds per session, given daily on 10 consecutive weekdays. Average muscle power appeared higher in the group given PBM across 6 months of follow-up. No adverse effects followed the use of PBM.

9 of 13 patients showed excellent improvement in a 2018 observational study of low-level laser therapy (LLLT) for weakness caused by injury to a nerve in the arm. The patients had developed the weakness from pressure on that nerve during awkward positioning and sleeping posture, and received 815 to 845 nm light at 1 W and 20.1 J/cm² for 30 seconds per session across 90 days, with muscle power in the wrist-lifting muscle graded by hand before and after treatment. According to the report, 4 of the 6 patients who also wore a brace showed excellent improvement. The report noted that maintaining the benefit depended on patients learning to avoid the postures that had caused the problem.

59% of patients reported feeling better after treatment in a 2025 observational study of photobiomodulation (PBM) for long-standing nerve injury in the jaw and tongue. 76 cases treated at a university clinic in Norway between 2007 and 2018 were examined, all involving nerve symptoms lasting more than 3 months, with 830 nm light delivered at 400 mW and doses between 13.3 and 40 J/cm², applied both inside and outside the mouth. The study found no statistically significant effect on those symptoms, and no link between the outcome and the patient's sex, the cause of the injury, which nerve was affected, how soon treatment began, or how many sessions were given. Because the study was retrospective and had no comparison group, the reported improvements could reflect placebo effects or the nerve recovering on its own.