Red light therapy relieves joint pain

For knee osteoarthritis, pooled analyses of small trials found less pain with red or near-infrared laser light than with a sham (fake) device, but the size of the effect is uncertain and three of the four individual trials cited here found no difference. A 2019 analysis of 22 placebo-controlled trials (1,063 people) found pain about 14 points lower on a 100-point scale at the end of treatment, and a 2024 analysis of 10 trials (542 people) found a moderate reduction in pain at rest while rating the certainty of that evidence very low. Three later trials are split: in a 2021 trial of 168 people in four groups, laser on its own meant less pain at rest than a sham for up to six months, while trials in 2022 (50 people) and 2023 (127 people) that added laser to a strengthening exercise programme found no extra pain relief over a sham laser. In a 2014 trial of 282 adults aged 50 or over with chronic knee pain, low-dose laser applied to acupuncture points was no better than a fake laser for pain or function after 12 weeks.

For other joints the picture differs by condition. A 2023 analysis of 18 trials in rheumatoid arthritis found that infrared laser may make little or no difference to pain compared with a sham device, rated low certainty, with 17 of the 18 trials at high risk of bias. A 2025 analysis of 18 trials (1,038 people) in jaw joint disorders (temporomandibular disorders) reported lower pain with light, most consistently when the problem was inside the joint. The UK's 2022 osteoarthritis guideline recommends against offering laser therapy, and its committee reported that trials of laser and electrical treatments were inconsistent and mostly showed little benefit. These sources studied osteoarthritis, rheumatoid arthritis and jaw joint disorders, mostly with lasers applied in clinics rather than the LED panels sold for home use, and they do not cover joint pain from gout, injury or infection.

Most trials used lasers at near-infrared wavelengths (roughly 785 to 905 nm, just beyond visible red) held on the joint by a clinician, usually two or three sessions a week for several weeks, and measured pain up to about three months later; the 2021 and 2023 knee trials followed people for six months and the 2014 and 2022 trials for a year. The 2019 analysis found larger effects at the doses a laser therapy association recommends, 4 to 8 joules per treatment spot at 785 to 860 nm or 1 to 3 joules at 904 nm, and classed the 2014 trial's 0.2 joules per point as below that range. The 2022 and 2023 knee trials used doses inside that range (3 joules per point at 904 nm and 6 joules per point at 808 nm) alongside strengthening exercise, and neither found a difference in pain from a sham laser; the 2022 trial was run by authors of the 2019 analysis. In both trials, pain on movement fell substantially in every group, including the groups given the sham. The reviews disagree on trial quality: the 2019 analysis judged the risk of bias insignificant, while the 2024 analysis judged all ten of its trials at unclear or high risk. In rheumatoid arthritis, only two small trials tested visible red laser against a sham, with results the authors of the 2023 rheumatoid arthritis review called very uncertain.

The proposed mechanism is that red and near-infrared light is absorbed by an enzyme in the mitochondria, raising energy production and damping inflammation and oxidative stress. That account rests on cell and animal work, and none of these sources measured it in a human joint. In the United States, lasers of this kind are cleared as Class 2 devices in an FDA category defined as non-heating lasers for adjunctive use in pain therapy, meaning use alongside other treatment. That classification records how the devices are regulated, not whether they relieve joint pain.

Side effects were rarely reported. The 2019 analysis found no adverse events reported in any of its trials, the 2014 trial reported no serious adverse events, and in rheumatoid arthritis one small red laser trial recorded a burning sensation in treated joints in three people, all in the laser group. None of the rheumatoid arthritis trials in the 2023 review compared light with the medicines used to control the disease itself, such as methotrexate; where those medicines appeared, light was added to them. Changes to arthritis treatment are a question for the treating clinician.