Red Light Therapy for Peripheral Neuropathy: Scientific Evidence

A 48-year-old man whose nerve damage followed a long-standing hormone disorder took part in a 2021 single-subject observational study in Springfield, Missouri, United States. He had lost feeling in both feet and had had balance problems for 10 years, and he received 890 nm near-infrared light in contact with the lower legs and feet for 30 minutes per session, across 15 sessions over 35 days. Blood flow measurements in the right foot changed significantly from the third week of treatment onwards, which the study interpreted as a widening of the small blood vessels. Feeling improved in both feet, and by the eighteenth session he reported noticing objects and creases in rugs underfoot. The left foot responded less well, which the study connected to 2 ankle fractures he had suffered as a young man.

Sham treatment produced no significant change at any point in a 2017 double-blind cross-over randomized controlled trial of photobiomodulation for nerve damage caused by chemotherapy. 70 patients at a university center in Minneapolis, Minnesota, United States, received 30-minute sessions 3 times a week across 42 days, using 800 to 970 nm light at 6.75 to 12 W and 20000 Hz, held 0.39 inches from the legs. Scores on a standard measure of nerve symptom severity decreased 32.4% at 4 weeks, 52.6% at 8 weeks, and 38.8% at 16 weeks in the treated group, and each difference against sham was statistically significant. Patients who crossed over to light therapy combined with physiotherapy reached similar figures, and adding physiotherapy did not improve on light therapy alone.

After finishing chemotherapy that contained a platinum drug, 17 cancer survivors in Taichung, Taiwan, took part in a 2016 single-arm observational study of laser acupuncture. 14 had been treated for bowel cancer, and 3 for stomach cancer, and each received 780 nm light at 50 mW, 48 J/cm², 115.2 J, and 100 Hz for 20 minutes at each of 10 acupuncture points on both sides of the body, across 12 sessions over 28 days. Pain quality, the severity of the nerve symptoms, and their effect on daily activities all improved significantly by the end of the course. Sensitivity to light touch and to cold, measured before and after, improved significantly as well.

Across 3 months of follow-up, a 2015 single-blind randomized controlled trial in Istanbul, Turkey, compared low-level laser therapy against therapeutic ultrasound in 32 patients with nerve compression at the elbow. The laser group received 905 nm light at 25 mW, 1500 mW/cm², and 0.8 J/cm² in contact with the skin for 30 seconds at each treated point, while the ultrasound group received 5-minute sessions, both given 5 times a week across 14 days. Pain, grip strength, and nerve conduction all improved significantly in both groups at the 1-month mark, with no significant difference between them. By 3 months, the ultrasound group held its gains across every measure, while the laser group kept significant gains in grip strength and nerve conduction only.

In 2009, an observational study followed an elite baseball pitcher who felt a deep ache along the thumb side of the forearm and altered feeling on the back of the hand while throwing. Low-level laser therapy at 630 to 1064 nm made up 1 part of the program, given across 10 sessions over 38 days alongside active rest, a stop on throwing, microcurrent therapy, myofascial release, augmented soft tissue mobilization, and neurodynamic mobilization, together with a sport-specific conditioning plan. Symptoms resolved and the pitcher returned to his pre-injury level within 5 weeks.

Researchers at a medical center in Redwood City, California, United States, treated 27 people with peripheral neuropathy in a 2004 observational study of near-infrared light. 21 of them had reduced feeling in the legs and feet linked to diabetes, and 6 had other causes, with each receiving 890 nm light at 480 mW, 8 mW/cm², and 292 Hz in contact with the skin for 40 minutes per session, across 10 sessions over 14 days. Every patient showed better sensation than before treatment, and 16 of the 27 reached normal responses across all the nerve fiber types tested. 10 of them had been tested about 27 months earlier and had shown no improvement on their own in the period since.

73 patients whose nerve damage came from pressure and reduced blood supply took part in a 2002 observational study of rehabilitation treatment. Each received pulsed infrared light between 780 and 1400 nm at 1 to 5 mW/cm² and at 5 and 5000 Hz, applied to the skin alongside the spine, over the affected nerves and at acupuncture points on the limbs. The report found that the laser treatment relieved pain and stimulated repair in the damaged nerve structures. Electrical stimulation of the nerves and the muscles they supply was then added, and the report credited that step with driving regrowth of the nerve fibers and restoring the nerve supply to the limb muscles.

This 1992 observational study studied how laser acupuncture affects pain in people whose nerve damage came from their work. It found that 632.8 nm light increased the body's own production of pain-reducing substances, which the report linked to restoring the ability to adapt to pain. A repeated course of laser therapy brought the levels of those substances back to normal. The report suggested that measuring them in the blood could help judge both the pain and the effect of laser therapy.

A 2024 single-blind randomized controlled trial in Bursa, Türkiye, tested low-energy laser therapy added to a resting splint and nerve release exercises for nerve compression at the elbow. 64 patients were split into 2 equal groups, with 32 receiving 685 nm low-level laser light at 27 mW, 5 J/cm², 10 J and 10 Hz for 6 minutes a session across 15 sessions over 21 days, and 32 receiving a switched-off laser alongside the same splint and exercises. Pain, function, muscle strength, and quality of life all improved in both groups at 3 weeks and again at 3 months. Pain at rest, pain on movement, and 3 measures on a patient-rated nerve scale favored the laser group significantly at 3 weeks, and only the pain measure still did so at 3 months. The trial concluded that laser was superior to placebo in the short term and equivalent in the medium term.

According to a 2022 randomized controlled trial in Concord, New South Wales, Australia, laser photobiomodulation and a sham device produced similar response rates in cancer survivors with lasting nerve damage from chemotherapy. 44 people whose chemotherapy had ended at least 3 months earlier were assigned 2 to 1 to laser or sham, receiving 658 nm light at 8 mW and 1 to 2 J twice weekly across 12 sessions over 42 days. 48% of the laser group and 53% of the sham group met the trial's definition of response at 6 weeks, and 45% and 33% did so at 12 weeks. Symptoms improved from baseline in both groups after treatment, with the gain holding in the laser group at 12 weeks while the sham group drifted back toward its starting point. Clinical signs, quality of life, and physical function stayed steady in both groups.

Whether light therapy could prevent nerve damage during chemotherapy was the question behind a 2022 placebo-controlled randomized controlled trial in Hasselt, Belgium. 32 breast cancer patients were split evenly between photobiomodulation and placebo, receiving 780 to 970 nm light at 80 mW to 25 W, 168 mW/cm² and 4 to 48 J/cm² for 10 seconds to 3.23 minutes per point, twice a week across 84 to 126 days. Scores on a standard measure of nerve damage increased significantly over time in both groups. Quality of life scores were significantly higher in the light therapy group during chemotherapy, and the sensory symptoms that worsened steadily in the placebo group held constant in the treated group. At follow-up, walking distance and pain levels differed between the groups in favor of light therapy, though only borderline so.

Searching 3 research databases up to the end of October 2015, a 2017 review examined low-level laser therapy for the loss of feeling caused by peripheral neuropathy. 10 of 35 articles met the criteria, covering 61 participants, with 6 on carpal tunnel syndrome, 3 on nerve damage from injury, and 1 on diabetes, using 660 to 860 nm light at 20 to 250 mW and 0.45 to 70 J/cm². 6 of the 10 studies reported less loss of feeling and better functioning of the sensory nerves after treatment. The review concluded that low-level laser therapy can improve sensory function, while noting that treatment regimens varied so widely that no single protocol could be recommended.

A double-blind design compared 780 nm low-level laser light against an inactive light source in a 2007 randomized controlled trial of long-standing damage to major nerves and to the nerve network in the shoulder. 18 patients in Tel Aviv, Israel, whose injuries had lasted from 6 months to several years, received 250 mW light from 15.8 inches away, applied through the skin for 3 hours over the damaged nerve and 2 hours over the matching part of the spine, in 21 daily sessions, delivering 45000 J/cm² and 30000 J/cm² to those 2 targets. Movement improved significantly more in the laser group than in the placebo group across 6 months of follow-up, and measurements of voluntary muscle activity improved significantly as well. Sensation showed no significant difference between the 2 groups.