Red Light Therapy for Neck Pain: Scientific Evidence

Low-level laser therapy (LLLT) against placebo was the comparison tested across 13 randomized controlled trials pooled in a 2022 systematic review and meta-analysis of 556 patients with neck muscle pain. The 13 trials used LLLT at 830 and 904 nm at fluences of 15 and 67 J/cm2 applied to the shoulder and neck muscles, with treatment frequency ranging from 1 to 10 sessions per week over 7 to 84 days, in a patient group that was 77% female with a mean age of 37 years. Pain reduction, pressure sensitivity, and right lateral neck bending all showed significant improvement in favor of LLLT, with mean differences of 1.29, 2.63, and 3.44, respectively, while disability scores did not reach significance. The authors recommended that LLLT may be most effective when paired with manual therapy or exercise rather than delivered as a standalone treatment.

In 2022, a single-blind randomized controlled trial investigated whether photobiomodulation therapy (PBM), ultrasound, or exercise alone could reduce neck pain and improve muscle function in 36 female sewing machine operators. The PBM group received 830 nm laser at 20 J/cm2 and 2.4 J per point at 30 mW in 80-second contact sessions 12 times over 42 days, applied to the neck and upper shoulder muscles, with pain, function, and muscle activation measured before and after the protocol across all 3 groups. Both the PBM plus exercise and ultrasound plus exercise groups showed greater pain improvement than the exercise-only group, with large effect sizes for pain reduction recorded in both active treatment groups. The PBM group also showed changes in shoulder muscle activation patterns that were not found in the other 2 groups.

Pain intensity was significantly lower in the active treatment group at every time point tested in a 2022 triple-blinded randomized controlled trial of 72 adults with chronic nonspecific neck and shoulder pain. The active group of 36 received photobiomodulation therapy combined with magnetic field (PBMT-sMF) at 630 to 650, 865 to 885, and 904 to 906 nm at fluences of 1.53 to 3.5 J/cm2 applied to 9 sites across the neck and shoulder in 3-minute contact sessions 6 times over 21 days, while the placebo group of 36 received an identical-looking inactive device. PBMT-sMF was associated with significantly greater pain reductions than placebo from 15 minutes up to 7 days after the final session, though no differences between groups were found for range of motion or treatment satisfaction. No adverse effects were reported in either group.

Comparing the efficacy of photobiomodulation (PBM) against physiotherapy was the focus of a 2021 randomized single-blind controlled trial of 60 office workers aged 25 to 55 years with chronic non-specific neck pain. 30 participants received high-intensity laser PBM at 780 to 830 nm, 15 and 100 J/cm2, 25 Hz, in 9-minute sessions delivered 10 times over 14 days to the neck, while the other 30 received physiotherapy over the same period. Pain and disability were measured using 4 questionnaires before treatment, immediately after, and 2 weeks later, and researchers found that both groups improved but the PBM group was associated with significantly greater reductions in pain and disability scores than the physiotherapy group.

A combined 635 nm red and 405 nm violet laser was compared against the 635 nm red laser alone in a 2019 observational study of 87 adults with chronic neck or shoulder pain lasting at least 30 days. 44 participants received a single 13-minute session with the combined laser delivering 4.68 J to the neck and shoulder at 7.5 mW, while 43 received the red laser alone under the same session conditions. It was reported that the combined laser group showed larger reductions in mean pain scores, dropping from 65.0 to 35.2, and greater improvement in shoulder range of motion compared to the red laser alone group.

75 patients with chronic neck pain (mean age 46.28 years, mean illness duration 5.98 months) were randomized into 3 groups in a 2017 randomized controlled trial comparing multiwave locked system laser therapy (MLS), low-level laser therapy (LLLT), and placebo laser, each combined with exercise. Group 1 received MLS at 808 nm continuous and 905 nm pulsed combined with exercise, Group 2 received LLLT at 830 nm combined with exercise, and Group 3 received placebo laser with exercise, all delivered at fluences of 4 and 50 J/cm2 to the neck muscles, shoulder, and trigger points, 12 times weekly over 42 days. Pain and disability scores fell significantly in all 3 groups, but the study reported that MLS plus exercise produced the largest reductions in pain (delta VAS 6.68) and disability (delta NDI 39.84) compared to LLLT plus exercise (delta VAS 5.72, delta NDI 37.88) and placebo plus exercise (delta VAS 4.84, delta NDI 36.68).

A multidisciplinary clinical practice guideline published in 2016 reviewed systematic evidence to develop treatment recommendations for adults with grades I to III neck pain lasting under 6 months. The guideline cited low-level laser therapy (LLLT) protocols using 830 and 904 nm delivered up to 12 times weekly over 28 days to the neck as a treatment option to consider. Researchers found that LLLT may be considered alongside exercise, massage, and other care options for neck pain lasting more than 3 months, but recommended against LLLT for grade III neck pain with neurological signs within the first 3 months. The guideline was developed by a 21-member expert panel drawing on evidence of effectiveness, safety, cost-effectiveness, and patient values.

Neck range of motion, pain, and disability all improved more in the laser group than in the placebo group in a 2016 randomized double-blind placebo-controlled trial of 60 male patients with chronic neck pain (mean age 35.47 years). The high-intensity laser therapy (HILT) group received treatment at wavelengths of 532, 780, 810 to 830, 820 to 830, 830, 904, and 1064 nm at an irradiance of 670 mW/cm2 and fluences of 0.36 to 27.3 J/cm2 applied to the neck, upper back, and tender points in sessions of 15 seconds to 15 minutes, delivered 12 times weekly over 42 days combined with exercise, while the placebo group received an inactive device with the same exercise program. The HILT plus exercise group showed significantly greater gains across all 3 outcome measures after 6 weeks compared with the placebo plus exercise group.

Patients with painful muscle knots in the upper shoulder muscle showed the greatest tendency toward progressive improvement in the laser group in a 2012 clinical trial comparing 3 treatments for neck pain in 45 participants (22 women and 23 men, aged 20 to 40). Each of the 3 groups of 15 received 5 daily sessions of either therapeutic laser at 904 nm and 0.074 J/cm2 for 30 seconds, therapeutic ultrasound, or pressure-based compression, with pain and neck side-bending movement assessed on day 1 and day 5. All 3 groups improved significantly across both assessment points, but researchers found a statistically significant difference in improvement between the laser group and the other 2 groups. Researchers concluded that laser therapy may be an effective treatment for painful muscle knots in the neck and the physical limitations they cause.

Chiropractic joint manipulation therapy (CMT), low-level laser therapy (LLLT), and their combination were compared in a 2011 randomized controlled study of 60 outpatient women aged 18 to 40 with neck joint pain lasting more than 30 days. Each participant received 6 treatments over 3 weeks, with LLLT delivered at 830 nm and an irradiance of 111 to 151 mW/cm2 at a dose of 5.57 to 7.56 J/cm2 to the neck joints, while the CMT group received spinal manipulation and the combination group received both. All 3 groups showed improvement in pain, disability, and neck movement range across the 4-week measurement period, but the combined CMT and LLLT group was associated with greater benefit than either therapy on its own. Researchers suggested both therapies may be beneficial for neck joint pain and called for further studies to define optimal treatment procedures.

60 patients with acute neck pain that radiated into the arm received either active low-level laser therapy (LLLT) or an inactive placebo laser across 15 sessions over 21 days in a 2010 double-blind randomized placebo-controlled trial conducted at the University of Belgrade, Serbia. LLLT was applied at 905 nm, 12 mW/cm2, 2 J/cm2 per site, at 5000 Hz in 2-minute sessions to the skin over the affected area of the spine, reaching a total dose of 12 J/cm2 per course. Statistically significant differences between groups in favor of LLLT were found for arm pain intensity (p 0.003, effect size d 0.92) and neck extension range of motion (p 0.003, effect size d 0.94) at the end of the 3-week treatment period.

16 randomized controlled trials with 820 patients were pooled in a 2009 systematic review and meta-analysis to assess the effect of low-level laser therapy (LLLT) on neck pain. Included studies used wavelengths of 632.8, 670, 780, 810 to 830, 820 to 830, 830, 904, and 1064 nm at power outputs ranging from 4 to 450 mW, with energy per point ranging from 0.06 to 54 J, delivered in 1-second to 10-minute sessions 1 to 15 times per week, applied to the neck. The review reported that LLLT was associated with a relative risk of pain improvement of 1.69 (95% CI 1.22 to 2.33) for acute neck pain and 4.05 (95% CI 2.74 to 5.98) for chronic neck pain versus placebo, with pain intensity reduced by a mean of 19.86 mm on a 100 mm pain scale. Side effects were mild and not different from those of placebo, and short-term pain relief was found to persist up to 22 weeks after treatment completion in chronic cases.

A randomized, double-blind, placebo-controlled study published in 2006 evaluated the effect of low-level laser therapy (LLLT) on chronic neck pain. 90 participants (59 women and 31 men, mean age 56.1 years) were randomized to receive 14 sessions over 7 weeks of either a 300 mW, 830 nm laser or a sham laser at an irradiance of 670 mW/cm2, applied to tender areas in the neck twice weekly for 49 days. The mean scores on a 10 cm pain scale improved by 2.7 in the treated group and worsened by 0.3 in the placebo group. Over 3 months, researchers also noted significant improvements in physical quality of life, neck-related function, and self-reported pain relief in the LLLT group. Adverse effects in both groups were mild, with nausea reported more often in the placebo group and stiffness more often in the laser group.

Multi-wave locked system (MLS) laser therapy was compared with a sham laser in a 2025 double-blind randomized controlled trial of 47 patients aged 20 to 65 with chronic non-specific neck pain. Both groups received 8 sessions over 17.5 days, with the MLS group treated at 808 and 905 nm at 5 J/cm2 in 7.67-minute sessions applied to the neck and shoulder muscles, and outcomes measured at the end of treatment and 1 month later for pain, disability, and head movement function. The MLS laser group was associated with significantly greater improvement in head lateral bending and rotation range of motion than the sham group, but pain and disability scores did not reach the threshold for clinically meaningful change in either group. Researchers noted a trend toward greater pain reduction in the MLS group at the 1-month follow-up.

4 treatments were compared head-to-head in a 2024 double-blind randomized sham-controlled trial of 144 participants with neck pain: photobiomodulation (PBM) combined with transcutaneous electrical nerve stimulation (TENS), PBM alone, TENS alone, and a sham group. The PBM groups received 808 nm light at 128.57 J/cm2 and 36 J in 50-second sessions applied to the neck, delivered 10 times over 14 days, with outcomes measured immediately after treatment and at 1 month. Neither PBM alone nor TENS alone was associated with significant reductions in pain at rest, but the combined PBM and TENS group showed greater reductions in pain during movement and greater overall sense of improvement compared to both the PBM alone and sham groups.

Promising results for pain relief and functional improvement emerged from a 2024 review of 36 clinical studies evaluating the effect of photobiomodulation (PBM) on shoulder and neck pain and disability. Of the 36 studies, 12 focused on neck conditions, 24 addressed shoulder conditions, and 1 examined both areas, with PBM delivered at infrared wavelengths of 780 to 1400 nm applied to the affected shoulder and neck regions. Researchers found that infrared wavelengths were the most commonly used and that PBM was associated with positive outcomes in many studies, though variability in treatment protocols across studies made it difficult to draw firm conclusions. The review described PBM as a safe and non-invasive option and called for further standardized trials to confirm its effectiveness across a wider range of conditions.

A 2022 systematic review of 7 randomized trials examined whether photobiomodulation therapy (PBMT) combined with therapeutic exercise could reduce pain intensity and neck disability in individuals with chronic neck pain. The 7 trials included approximately 500 participants and used infrared laser wavelengths of 632.8, 670, 780, 808, 830, 904, and 905 nm at fluences of 2 to 7 J/cm2 applied to the upper shoulder, in sessions ranging from 30 seconds to 7.82 minutes, delivered 10 to 30 times weekly over 14 to 42 days, with study quality scores ranging from 5 to 8 on the PEDro scale. Most trials reported reductions in pain intensity and neck disability when PBMT was added to exercise, though variability in treatment parameters and results across studies meant firm conclusions could not be drawn.

A 2013 systematic review and meta-analysis pooled 8 randomized controlled trials with 408 participants (age range 32 to 56) to evaluate the effect of low-level laser therapy (LLLT) on acute and chronic neck pain. The 8 trials used wavelengths of 632.8, 830, 904, and 905 nm at irradiances of 100 to 1000 mW/cm2 and a dose of 9 J/cm2, delivered in 10-minute sessions up to 12 times weekly over 14 to 28 days to painful muscle points in the neck and shoulder. A pooled analysis of 5 trials focused on neck muscle pain found LLLT associated with a mean pain score improvement of 10.54 mm on a 100 mm pain scale (95% CI 0.37 to 20.71), which was statistically significant but did not reach the threshold considered clinically meaningful. The authors concluded the overall evidence was inconclusive due to significant differences between studies and potential risk of bias.

4 out of 5 randomized controlled trials reported positive results for infrared laser applied to the neck in a 2005 systematic review pooling 273 participants. The review examined studies using infrared wavelengths of 780, 810 to 830, 904, and 1064 nm applied to the neck, though differences in outcome measures, doses, and laser settings across trials made it impossible to combine results into a single pooled estimate. Researchers found limited evidence supporting infrared laser for both short-term acute neck pain, drawn from 1 trial of 71 participants, and chronic neck pain, drawn from 4 trials of 202 participants. The authors called for larger studies to confirm the positive findings and identify the most effective wavelengths, treatment sites, and application methods.

Researchers in Brazil tested whether 1 session of low-level laser therapy (LLLT), far-infrared radiation, or sham laser differed in short-term effects on pain intensity, pressure-induced pain, and shoulder skin temperature in a 2025 randomized sham-controlled trial of 91 individuals with subacute and chronic neck pain. The 3 groups received either 808 nm LLLT at 0.5 J/cm2 and 10 mW, a 30-minute far-infrared application at 30 cm and 90 degrees, or a simulated laser applied to the shoulder muscle over 2 days. All 3 groups showed pain score reductions within each group across the 5 measurement time points up to 48 hours, but no significant differences were found between groups for pain intensity or pressure-induced pain, and far-infrared briefly raised shoulder skin temperature at early time points compared to LLLT and sham. The authors concluded that a single phototherapy session was not effective in the short term for subacute and chronic neck pain.