High-Intensity Laser Therapy Cuts Pain Across 105 Clinical Trials
A meta-analysis published September 2026 in Frontiers in Integrative Neuroscience pooled 105 clinical trials and found that high-intensity laser therapy reduced pain with large effect sizes in more than 90% of trials for knee, spine, shoulder and wound pain, with no serious side effects among 2,710 treated patients.
The review combined 105 randomized trials from 2018 through April 2026, testing Class IV high-intensity laser therapy (HILT) against controls or low-level laser therapy in 2,710 treated patients and 2,925 controls. HILT used a mean power of 9.3 watts (range 0.5-30) and mean power density of 19.5 watts per square centimeter, about 100 times the power of low-level lasers, which top out near 0.5 watts. Pain scores fell by a standardized effect size of 0.98 at treatment's end (50 trials), 1.18 within three months (19 trials), and 1.01 after three months (21 trials); values above 0.8 count as large. More than 90% of knee (27), spine (20), shoulder (20) and wound (2) trials showed large pain reductions. Range of motion improved in 92% of trials, functional performance in 84%, and quality of life in 85%. HILT outperformed low-level laser therapy in all 13 head-to-head comparisons, with no serious adverse events reported.
HILT Pain Reduction Effect Size Across Follow-Up (105 trials, n=2,710)
The authors attribute HILT's advantage to raw power: standard low-level lasers put out too little energy to reach past skin and shallow tissue, while HILT's roughly 100-fold higher output lets light penetrate deep enough to reach joints, tendons, discs and muscle. Photobiomodulation, the general term for therapeutic light treatment, works by prompting cells to generate more energy and calm local inflammation, an effect the authors say stays shallow at low power but reaches deeper structures once power increases.
This is a review of existing trials rather than a new experiment, and quality varied across the 105 studies included; patients could often tell which device was used, limiting blinding. Effect sizes are standardized statistical measures, not point changes on a pain scale, and funding for the review was not reported.
Data Panel
- Who
- 2,710 patients treated with Class IV high-intensity laser therapy and 2,925 controls, pooled across 105 randomized trials; age and sex not reported.
- Design
- Systematic review and meta-analysis of 105 randomized controlled trials published 2018 to April 2026, comparing high-intensity laser therapy (HILT, 0.5-80 watts) with controls or low-level laser therapy for musculoskeletal and other conditions.
- Dose
- Mean HILT power 9.3 W (median 10.0, range 0.5-30 W); mean power density 19.5 W/cm2 (median 10, range 0.1-52.5 W/cm2).
- Primary result
- Pain reduced with large standardized effect sizes in more than 90% of trials for knee (27), spine/nerve (20), shoulder/arm (20) and wound (2) conditions; standardized pain-score reduction was 0.98 at end of treatment (50 trials), 1.18 under 3 months (19 trials), 1.01 at 3+ months (21 trials).
- Secondary
- Range of motion improved in 92% of trials (26); functional performance in 84% (57); quality of life in 85% (25). HILT beat low-level laser therapy in all 13 head-to-head comparisons. No serious adverse events reported.
- Funding / conflicts
- Not reported.
Dr. Axe's Take
I think this review confirms something worth taking seriously: power output determines whether a laser actually helps a deep joint or just warms the skin. Low-level lasers rarely reach a stiff knee or an aching disc; Class IV lasers, running roughly 100 times stronger, do. If you have chronic knee, shoulder or spine pain that has not responded to physical therapy or anti-inflammatory eating, I would ask a provider whether they use a true Class IV high-intensity laser, not a handheld low-level device, and commit to a full series of sessions rather than one visit. Pair it with movement, anti-inflammatory foods, and red light therapy at home to support the same cellular energy pathways.
— Dr. Axe