Protocol · graded by use, four uses
Red Light / Near-Infrared (630–850nm)
Graded on: skin aging, knee osteoarthritis pain, diabetic foot ulcer healing and venous leg ulcer healing, each graded on its own row.
Grade C: human trials exist, but they are small, mixed or not yet repeated. This is not a finding that it does not work. How to read a grade →
Compare this record with another, side by side →
How this letter has changedLatest: October 2026 · Corrected.
The general page stated that the evidence for knee osteoarthritis pain and wound healing was small and mixed without citing it. It now carries four uses with their own letters and citations: skin aging C, on small trials including Lee et al. (J Photochem Photobiol B, 2007; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 17566756); knee osteoarthritis pain C, where meta-analyses A study that pools the numbers from several trials into one combined estimate. disagree, Stausholm et al. (BMJ Open, 2019; PMID 31662383) positive and others not, mostly on lasers outside 630 to 850 nm; diabetic foot ulcer healing C, on three positive meta-analyses of small trials including Li et al. (Diabetes Res Clin Pract, 2018; PMID 30009935); venous leg ulcer healing C, on small trials with mixed results including Lundeberg and Malm (Ann Plast Surg, 1991; PMID 1793238). Headline letter unchanged at C. Editor adjudication, October 2026.PMID 31662383 PMID 25914044 PMID 30009935 PMID 1793238 PMID 17566756
The general red and near-infrared light page held one B across pain, wound healing, skin aging and cognition, on one skin trial (Wunsch et al., Photomed Laser Surg 2014; PMID 24286286) and a mechanism review. Searched use by use in October 2026, those uses rest on small, mixed or self-reported trials, which is C. Oral mucositis prevention keeps its A on its own page. Editor adjudication, October 2026.PMID 24286286
Every change to a letter on this site is dated and published. The full evidence log →
Red and near-infrared light therapy shines specific colors of light on the skin. Small studies found smoother skin and fewer wrinkles. For knee arthritis pain, reviews of the studies disagree. Small studies also looked at healing of foot sores in diabetes and leg sores from poor circulation. Each use rests on small or mixed studies.
All four uses graded on this record carry a C, each on its own evidence.
This record carries a separate letter for each thing it has been measured on. The headline grade is the best of them, and it does not transfer to the others.
This page grades red and near-infrared light use by use, because the evidence differs by use. Skin aging, knee osteoarthritis pain, diabetic foot ulcers and venous leg ulcers each carry their own letter below, and each is C: small or mixed randomized trials, most of them on lasers or LED devices whose settings differ from one trial to the next. Preventing oral mucositis during cancer treatment is graded A, and musculoskeletal pain more broadly B, on their own photobiomodulation pages. Device settings matter: irradiance at the treatment distance is the variable most consumer devices do not report.
Why this gradeGrade C, small or unreplicated trials. The reasoning, and what the grade does not cover.
Grade C for red and near-infrared light in general, because no single use carries more than C. Each use is graded on its own row: skin aging on several small randomized trials (for example Wunsch et al., 2014; PMID 24286286); knee osteoarthritis pain on meta-analyses that disagree (Stausholm et al., 2019; PMID 31662383; Huang et al., 2015; PMID 25914044); diabetic foot ulcer healing on three positive meta-analyses of small trials (Li et al., 2018; PMID 30009935); and venous leg ulcer healing on small trials with mixed results (PMID 1793238). The mechanistic review of anti-inflammatory effects carries no letter (Hamblin et al., 2017; PMID 28748217). Pressure ulcers are not graded here: a systematic review A review that searches for every study on a question using a method set in advance, then assesses them together. found only four small trials and no consistent effect (Machado et al., 2017; PMID 28116536).
WHAT THIS GRADE DOES NOT COVERpreventing oral mucositis during cancer treatment, graded A, and musculoskeletal pain more broadly, graded B, each on its own photobiomodulation page; cognition, graded on the transcranial photobiomodulation page; and any specific device, since irradiance at the treatment distance is the variable most consumer devices do not report.
A grade describes the human evidence for a named use. It is not advice, and it is not a judgment on any individual prescription. How the letters are decided →
The evidence, in full17 papers, each linked to its PubMed record.
Wunsch et al. (Photomed Laser Surg, 2014; PMID 24286286): randomized controlled trial People are assigned to the treatment or a comparison by chance, so the groups differ only in what they received. It is the design that can show cause and effect. of red and near-infrared light on skin complexion and patient satisfaction. Hamblin et al. (AIMS Biophys, 2017; PMID 28748217): mechanistic review of the anti-inflammatory effects of photobiomodulation; carries no grade. Skin aging: Lee et al. (J Photochem Photobiol B, 2007; PMID 17566756), Mota et al. (Photobiomodul Photomed Laser Surg, 2023; PMID 36780572), Bragato et al. (Lasers Med Sci, 2025; PMID 40167796). Knee osteoarthritis pain: Stausholm et al. (BMJ Open, 2019; PMID 31662383), Huang et al. (Osteoarthritis Cartilage, 2015; PMID 25914044), Oliveira et al. (Phys Ther, 2024; PMID 38775202), Fan et al. (Aging Clin Exp Res, 2024; PMID 39367994). Diabetic foot ulcers: Li et al. (Diabetes Res Clin Pract, 2018; PMID 30009935), Zhou et al. (Wound Repair Regen, 2021; PMID 33078478), Santos et al. (Int J Low Extrem Wounds, 2021; PMID 32394760). Venous leg ulcers: Lundeberg and Malm (Ann Plast Surg, 1991; PMID 1793238), Malm and Lundeberg (Scand J Plast Reconstr Surg Hand Surg, 1991; PMID 1780722), Caetano et al. (Photomed Laser Surg, 2009; PMID 19196110), Bavaresco et al. (Rev Bras Enferm, 2021; PMID 34787240). Pressure ulcers, not graded: Machado et al. (Lasers Med Sci, 2017; PMID 28116536).
For musculoskeletal applications, use the VAS pain scale and range of motion measurement at baseline and 4 weeks. For skin applications, use standardized photography and a validated skin aging scale at baseline and 12 weeks. Treatment parameters (wavelength, irradiance, treatment area, session duration): these determine dose and two devices at the same wavelength can deliver very different energy doses.
Evidence notes: meta-analysis, randomized trial
Endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score. graded: Skin aging, knee osteoarthritis pain, diabetic foot ulcer healing and venous leg ulcer healing, each graded on its own row (surrogate)
Last reviewed: July 2026
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These statements have not been evaluated by the Food and Drug Administration. Any grade on this page describes the strength of published human trial evidence in the populations studied. It is not a recommendation for any individual and is not medical advice. Starting, stopping or changing any supplement or medication is a decision for your physician.
How EBL searched for the trials (1 search)
The search that was run, what it returned, and what was left out and why, so the absence of evidence can be checked as well as its presence.
(photobiomodulation[tiab] OR "low-level light"[tiab] OR "red light"[tiab]) AND (skin[tiab] OR wrinkle*[tiab] OR rejuvenation[tiab]) AND randomized controlled trial[pt]Grades move when new trials publish. A free monthly email lists every grade EBL moved, with the reason and the trial behind it: the sign-up is on the Evidence Log →