Red Light Therapy for Wound Healing: Scientific Evidence

Researchers in Italy tested a fluorescence-based light gel treatment delivering 440 to 460 nm light at an irradiance of 55 to 129 mW/cm² for hard-to-heal chronic wounds, including venous leg ulcers, diabetic foot ulcers, and pressure ulcers, in 99 patients as part of a 2018 real-world clinical trial, applied for 5 minutes twice a week over 16 to 24 weeks. Total wound closure was achieved in 47 of 99 patients (47%), including half of the venous leg ulcers and half of the diabetic foot ulcers, and average wound area shrank significantly for both of those wound types. Adherence to treatment was high, no serious related side effects occurred, and quality-of-life scores improved significantly, leading the researchers to describe the treatment as effective for these 3 types of hard-to-heal chronic wounds.

A 2018 review from South Africa examined how photobiomodulation may activate a growth-factor signaling pathway that guides the connective-tissue-building cells responsible for closing a wound, across a wide range of tissues including skin, oral tissue, and bone. The review described light treatment as helping regulate this pathway to support tissue rebuilding while also calming excess inflammation, drawing mainly on laboratory and cell-level research rather than patient outcomes. As a mechanism-focused review spanning many tissue types rather than a study of wound patients, it offers a proposed biological explanation rather than direct clinical evidence.

In 2018, a randomized controlled trial in Iran tested low-level laser therapy, at wavelengths of 650, 655, and 808 nm, an irradiance of 600 mW/cm², and a fluence of 2 to 6 J/cm², given daily for 7 days as an add-on to skin-graft surgery in 9 patients with deep burn wounds on the hands or feet, compared with standard dressing alone. Wound reopening after the graft was significantly less common in the laser-treated group than in the group receiving standard dressing alone. Because laser treatment was combined with the graft surgery rather than tested on its own, the trial shows a benefit for the combined approach without isolating how much came from the light itself.

Researchers examined how a cell-signaling pathway that carries repair instructions to the cell's control center may be involved in chronic wound healing in a 2017 review, particularly in diabetic ulcers treated with red and near-infrared light at 632.8 and 810 nm. The review described this signaling pathway as central to how cells receive growth-factor instructions during healing, and disruption of the pathway as a possible contributor to wounds becoming chronic and non-healing. As a mechanism-focused review rather than a study of treated patients, it proposes a biological explanation rather than reporting new wound-healing outcomes.

Comparing standard care against added helium-neon laser therapy at 632.8 nm, a 2017 randomized controlled trial in China tested wounds following nail surgery. Wound healing time was significantly shorter in the laser group, at roughly 11 days on average compared with 16 days in the control group, and the period of wound inflammation was shorter as well. The researchers concluded that helium-neon laser therapy helped speed wound healing after nail surgery.

Published in 2017, a prospective, double-blind randomized controlled trial tested light-emitting diode (LED) light at wavelengths including 625, 660, and 850 nm, at a fluence of 0.0022 to 2.4 J/cm² for 5 minutes per session, given 3 times a week for 8 weeks, against a placebo device in 79 patients with chronic wounds below the knee, some with diabetes and some without. The study's main measure was blood flow in the healthy skin at the wound's edge, on the reasoning that adequate blood supply is necessary for a wound to heal, rather than wound size or closure time directly. Blood flow at the wound edge improved significantly more with active LED treatment than with placebo. This offers evidence that the light supports a condition necessary for healing rather than a direct measurement of wound closure.

A non-invasive, drug-free treatment approach is proposed in a 2017 review from India examining red and near-infrared light-based photobiomodulation for hard-to-heal skin wounds. The review described this light therapy as a promising option for supporting wound healing while also reducing inflammation, pain, and loss of function, citing the light's ability to penetrate tissue and influence cell-level repair processes. As a general overview rather than a study of specific patients, the review outlines the case for the therapy's potential rather than reporting new clinical results of its own.

Among 120 patients undergoing coronary bypass surgery, some with high blood sugar and some without, a 2017 double-blind randomized controlled trial in Brazil tested red laser light at 640 nm and red light-emitting diode (LED) light at 620 nm on the chest incision, compared with placebo and untreated control groups. Both the laser and LED groups showed less redness and less incision bleeding or separation than the comparison groups, similarly, with no meaningful difference between patients with high versus normal blood sugar. The researchers concluded that both laser light and LED light supported healing of the surgical incision by day 8 after surgery.

Wavelengths of 650, 660, and 810 nm were tested via low-level laser therapy, at irradiances of 200 to 600 mW/cm² and fluences of 2, 6, and 10 J/cm² over 16-minute sessions, alongside standard skin-graft surgery in 6 diabetic patients (2 women and 4 men, mean age 49.1 years) with severe, grade 3 burn wounds, in a 2016 clinical trial in Iran. The combined approach was linked to healing times comparable to or better than typical outcomes reported elsewhere for diabetic burn patients undergoing grafting alone. Because laser treatment was used together with grafting surgery rather than tested on its own, the trial cannot show how much of the improvement was due to the light rather than the graft itself. The authors described the findings as an initial report rather than controlled evidence.

When researchers in Iran examined the proposed cellular mechanisms behind low-level laser therapy in a 2014 review, they covered a wide span of uses including pain, jaw-joint problems, nerve injury, and wound healing, at wavelengths from roughly 300 to 1200 nm. The review described how cells absorb this light to boost their internal energy production, which the authors linked to increased growth and movement of the connective-tissue-building cells involved in wound repair, among other effects. Wound healing was only one of several conditions covered rather than the review's central focus, and no wound-specific study results were reported.

Treating a non-healing ankle ulcer with red and near-infrared LED light alongside intravenous antibiotics, a 2014 clinical trial from India treated an 18-year-old man with thalassemia intermedia, an inherited blood disorder, and a 6-month-old wound, using wavelengths between 660 and 950 nm at an irradiance of 50 mW/cm² and fluences of 17.3 and 8.65 to 4.33 J/cm², 3 times a week for 6 weeks. Healthy new healing tissue was observed to develop over the treatment course, and the wound went on to close. Because the light therapy was given together with antibiotic treatment for the wound's infection, the trial cannot separate how much of the healing came from the light itself versus the antibiotics.

Whether laser light and several other emerging methods could help treat chronic, infected, and slow-healing wounds was the focus of a 2014 review from Germany, which listed low-level laser therapy alongside cold plasma, shock wave treatment, water-filtered infrared light, and electrical stimulation. The review described these methods, laser light included, as sharing at least an indirect antimicrobial effect useful as an add-on within a broader, specialist-led wound-care plan, without singling out laser therapy's own results or dosing details. As a general survey of several different technologies rather than a focused study of light therapy, this review offers limited wound-specific evidence for laser treatment on its own.

2014 brought a review from Brazil gathering published research on low-level laser therapy for wound healing in both human and veterinary medicine, spanning wavelengths from about 633 to 1000 nm. Doses between 3 and 6 J/cm² appeared most effective across the studies reviewed, while doses above 10 J/cm² were linked to harmful rather than helpful effects on healing. The review concluded that laser therapy can safely speed the healing of skin wounds, but only when wavelength, dose, and exposure time are chosen carefully.

5 of 5 wounds studied, in 5 patients ranging in age from 7 to 54 years (2 males and 3 females), achieved full healing after 830 nm light-emitting diode (LED) light therapy, given at an irradiance of 40 to 100 mW/cm² and a fluence of 60 J/cm² in 11-minute sessions, in a preliminary 2013 clinical trial, despite differing widely in cause and stage, including surgical injuries and a viral skin lesion. Infection and discomfort were also brought under control in all cases, over treatment periods ranging from 1 to 8 weeks depending on the wound, and no recurrence of the viral lesion at 4-month follow-up. Because the wounds studied varied so widely in type and cause and the group was so small, the authors called for larger, controlled studies to confirm these preliminary results.

16 Korean patients with venous stasis ulcers took part in a 2013 clinical trial combining injections of the patient's own platelet-rich plasma with light-emitting diode (LED) light at 635 and 830 nm and a fluence of 108 J/cm², given 3 times a week for 6 weeks. Ulcer size and related symptoms, including pain, itching, and swelling, improved significantly, and 75% of patients reported being satisfied or very satisfied with the results, with no worsening cases and no significant side effects. Because the plasma injections and LED light were given together rather than separately, the trial cannot say how much of the improvement came from the light alone, and the authors called for further studies comparing the combination against each treatment on its own.

According to a 2012 review from China, low-level laser therapy is thought to regulate cell behavior with light, with reported effects on tissue repair, inflammation, and pain drawn from laboratory and clinical research at wavelengths including 1565 nm. The review did not report specific measured outcomes of its own, instead describing the therapy's proposed biological effects and noting its growing experimental and clinical use abroad. As a general summary rather than a study with its own results, this review offers background on the therapy rather than direct evidence of its effect on wound healing.

This 2012 clinical trial treated a 69-year-old man with Klippel-Trenaunay syndrome, a condition affecting blood vessel and tissue growth, who had a non-healing ankle-area ulcer of 6 months' duration with heavy discharge and odor at the start of treatment. Treatment with light-emitting diode (LED) light, using red and near-infrared wavelengths between 632.8 and 950 nm, at an irradiance of 50 mW/cm² and a fluence of 1.58 to 22.8 J/cm², over roughly 7 months, was followed by a rise in new healing tissue, less discharge and odor, and improvement on a standard scoring tool for how a wound is healing, ending in complete closure of the wound. As a single-patient clinical trial, the finding is suggestive rather than proof of what LED therapy would achieve more broadly in this rare condition.

Nipple lesions healed faster with active LED phototherapy than with a placebo device, according to a 2012 randomized controlled trial in Brazil that enrolled 30 breastfeeding women with nipple trauma, testing 860 nm LED light at an irradiance of 50 mW/cm² for about 79 seconds per session, with both groups also receiving breastfeeding-technique guidance. Nipple lesions shrank significantly in both groups over the 4-week treatment course, but the reduction was significantly greater in the group receiving active LED light, and pain eased significantly only in that group. The authors described the prototype device as effective, though the findings were preliminary.

Published in 2012, a 4-arm randomized controlled trial compared water-filtered infrared light at 780 to 1400 nm, delivered at an irradiance of 210 mW/cm², a standard wound cream, the 2 combined, and no treatment at all, on small experimental wounds created on the forearms of 13 healthy volunteers (aged 23 to 47 years, 7 women and 6 men). Researchers tracked how quickly bacteria naturally present on the skin recolonized the wounds over 7 days of daily light sessions lasting up to 30 minutes. Every active treatment, including light alone, held back bacterial regrowth compared with no treatment at all, though the standard wound cream produced the strongest suppression of the 3 approaches.

Across a wide range of skin uses including pain control, acne, skin rejuvenation, and wound healing, a 2011 review from Korea surveyed light-emitting diode (LED) phototherapy at wavelengths mainly around 633 and 830 nm. Wound healing was one of several applications discussed rather than the review's central focus, and the authors described LED treatment broadly as at least partly effective when wavelength and dose match the target tissue, without providing wound-specific figures such as closure rates or healing time. Given its broad scope across many skin conditions, this review offers general context on LED phototherapy rather than focused evidence on wound healing specifically.

Researchers tested low-level laser therapy at 785 nm, added to a standard wound-care and prevention program, in 16 residents of a Canadian nursing home with a combined 21 measurable open wounds, including pressure, diabetic, and circulation-related ulcers, in a 2008 clinical trial conducted over 9 weeks, with sessions lasting 30 seconds to 2 minutes given 3 to 5 times a week. The program combining laser therapy with standard wound care was associated with healing progress across the resident group, according to the study, though the report did not include a separate comparison group treated with standard wound care alone.

Whether a novel infrared pulsed-light mechanism could enhance the body’s own tissue-repair processes was explored in a 2005 review, focusing on a device delivering 904 nm light and touching on effects in eye tissue as well. The reviewed studies suggested this pulsed light could support repair processes non-invasively, with effects reaching beyond the immediately treated site, though the review authors described this as an early-stage explanation rather than a settled mechanism. Additional studies were said to be needed to confirm how broadly this effect applies.

Applying 904 nm low-level laser therapy to postoperative wounds, a 2005 clinical trial treated 2 patients recovering from foot surgery. According to the researchers, both patients’ wounds healed successfully, and their return to ordinary daily activity happened faster than would typically be expected without treatment. Because the report describes only 2 cases rather than a controlled comparison group, it offers preliminary rather than definitive evidence for the treatment's effect.

Among 22 healthy volunteers in the United States, with a mean age of 21 (±1) years, a 2004 randomized controlled trial, using a triple-blind, sham-controlled design, tested whether low-level laser therapy could speed the healing of small experimental skin wounds. Participants received 820 nm laser light at an irradiance of 75 mW/cm² and a fluence of 8 J/cm² for just over 2 minutes per session, 10 sessions across 10 days, to test wounds on the forearm, while sham wounds received an inactive device. By days 6, 8, and 10, laser-treated wounds had become significantly smaller than sham-treated wounds, and even nearby untreated wounds on laser-treated participants shrank more than those on sham participants, suggesting the light may have produced a wider, indirect healing effect beyond the treated site.

34 of the studies reviewed in a 2004 meta-analysis focused on tissue repair and 9 on pain control, examining low-power laser therapy at wavelengths from 514 to 904 nm in the United States. The analysis found a clear positive effect of laser treatment on both tissue repair and pain control, with specific benefits reported for markers of new tissue formation and wound strength. The reviewers concluded that laser phototherapy is a highly effective treatment for tissue repair and pain relief.

A combined effect size of +2.22 emerged from a 2004 meta-analysis in the United States pooling 24 studies and 31 treatment comparisons on laser therapy, using wavelengths of 780, 830, and 904 nm, for wound and tissue healing. The analysis found significant improvements in both animal research and human clinical studies, with specific gains in areas such as new tissue strength and the pace of the inflammatory and repair process. The reviewers concluded that laser therapy is an effective tool for promoting wound repair.

714 participants across multiple studies showed evidence of faster wound healing and pain relief after low-intensity laser therapy at wavelengths including 630, 809, 830, and 860 nm, according to a 2004 review that also covered other applications in the eye, joints, and mouth. The review authors noted evidence that laser treatment could also strengthen surgically repaired tendon and ligament tissue and support fracture healing. The authors acknowledged that questions remain about standardizing treatment settings, even as they described the field's clinical use as growing rapidly.

Across the molecular and cellular research it drew on, a 2004 review examined the stimulating effect of low-intensity red light, spanning 620 to 780 nm, on wound tissue. The authors described how skin cells involved in healing, including immune cells and connective-tissue-building cells, absorb this light and generate a cascade of chemical reactions inside the cell that can promote tissue repair. Because the review drew on laboratory and cell-level research rather than patient outcomes, it offers a proposed biological explanation rather than direct evidence of wound healing in patients.

100% of 20 patients with chronic skin ulcers of varied causes and locations achieved complete wound closure in a 1999 clinical trial of low-intensity helium-neon laser therapy in Austria. All had resisted a median of 34 weeks of conventional wound care before receiving 632.8 nm laser light at a fluence of 30 J/cm² 3 times a week for a median of about 12.5 weeks. Though the researchers found that ulcer cause and wound size significantly affected how long healing took, every patient's ulcer closed by the end of the study.

This 1997 clinical trial from Austria treated a single patient with a long-standing foot ulcer caused by past radiation treatment, using a low-power helium-neon laser at 632.8 nm. Treatment was given in sessions lasting 35 minutes, 20 times a week, over roughly 10 weeks, at an irradiance of 8 mW/cm² and a fluence of 31.5 J/cm². The ulcer, which had resisted more than 45 years of other treatment attempts, went on to heal successfully with the laser therapy, according to the trial.

A human study published in 1992 assessed red light therapy for delayed postoperative open wounds that were resistant to conventional treatment. Twenty-one patients with 31 wounds were randomly assigned to three groups: red low-level narrow-band light at 660 nm, infrared LLNB at 940 nm, or a placebo device that emitted no light. The groups were compared and analyzed using t-tests. The researchers reported that the 660 nm red-light group showed significant improvement in wound healing compared with both the 940 nm infrared group and the placebo group, indicating an effective result for the red LLNB treatment in this trial.

A human study published in 1988 assessed red light therapy for healing open wounds. This clinical report described two patients treated in a physical therapy department who received infrared cold laser therapy (780–1400 nm) together with conventional sterile whirlpool baths using povidone-iodine. The authors reported clinical results showing well-granulated tissue and nearly complete healing of the open wounds in both patients. Overall, the report concluded the combined whirlpool and infrared cold laser protocol was effective in these two cases, though it only describes this small clinical experience.

Published in 1985, a clinical trial treated 274 patients with infected wounds of the soft tissue using standard drug therapy plus a helium-neon laser, delivering red light between 620 and 780 nm. Adding the laser to standard care was linked to reliably faster wound cleansing, along with stronger growth of new healing tissue and skin regrowth over the wound surface. No treatment-related complications were reported among the study's participants.

According to a 2020 national expert consensus statement from China, the evidence for light-based treatment of acute and chronic wounds, including diabetic foot ulcers, venous leg ulcers, pressure ulcers, and burns, was reviewed across a wide range of red and near-infrared wavelengths from about 405 to 3400 nm. The panel identified red light in particular as the most widely used and best-supported option for speeding wound healing, easing pain, and controlling wound fluid, based on their review of the published literature and discussion among wound-care specialists. As a consensus statement built on existing published evidence rather than a new study of patients, it reflects expert judgment rather than newly reported outcomes.

Across venous ulcers, diabetic foot ulcers, pressure ulcers, and burn wounds, a 2019 continuing-education review from the United States summarized the evidence for light-based treatments, including lasers and light-emitting diode (LED) devices, at wavelengths from about 405 to 1000 nm. The review described a range of doses and devices used across the studies it covered, while noting a lack of agreement among researchers on standardized treatment settings such as wavelength and dose. Written as an educational overview for clinicians rather than a new patient study, it makes the case for light therapy's promise in wound care without adding new outcome data of its own.

No separate wound-specific closure or healing-time figures were reported in a 2018 systematic review of home-use photobiomodulation devices, drawing on 11 studies and 333 participants across uses including pain, cognitive difficulties, and wound healing, at wavelengths mostly in the near-infrared range. Wound healing was just one of several conditions covered, and the review reported mostly positive results across the studies it covered. The reviewers concluded that home-use light devices appear to offer effective, safe treatment across these varied conditions, but said more randomized controlled studies are needed to confirm this.

43% of patients achieved complete wound closure by 3 months in a 2017 clinical trial in Italy testing polarized light therapy, spanning wavelengths from 480 to 3400 nm at an irradiance of 40 mW/cm², for 30 patients (19 women and 11 men) with chronic skin and mucosal ulcers, given for 20 minutes twice a week over 12 weeks (24 sessions in total). By 2 months, at least half the lesion had closed in 18 of 30 patients (60%), alongside reductions in discharge, pain, and signs of infection in most patients. The researchers described the results as supporting polarized light as part of a broader, non-drug approach to chronic wound care rather than a stand-alone cure.

Leg swelling and a leg ulcer both improved over a course of combined care, according to a 2016 clinical trial from the United Kingdom describing a 65-year-old man with long-standing leg swelling, paraplegia, and arterial disease, managed with compression bandaging, a specialized wrap, daily 904 nm low-level light therapy over about 10 weeks, and wound dressings alongside separate treatment to restore blood flow to the leg. The patient's leg swelling reduced, the ulcer healed, and quality of life reportedly improved over the course of care. Because light therapy was just one part of a broader treatment plan that also included a procedure to restore blood flow and several other supportive measures, this case cannot show what the light therapy itself contributed to the healing.

17 patients with chronic venous leg ulcers experienced fewer treatment-resistant cases after weekly 625 nm light-emitting diode (LED) light, at a fluence of 4 J/cm² for about 2.5 minutes per session, alongside standard compression bandaging over 30 weeks in a 2015 randomized controlled trial in Brazil, compared with a placebo device plus the same bandaging. Total ulcer area and healing rate did not differ significantly between the LED and placebo groups, and LED treatment did not change the local level of an inflammation-related marker in the wound fluid. However, none of the ulcers in the LED group became treatment-resistant after 19 weeks, compared with 6 such cases in the placebo group, suggesting the light may help prevent ulcers from stalling even though it did not speed healing in general.

A 2012 review examined the role of an inflammation-related enzyme in tissue repair driven by low-level laser therapy, drawing on wavelengths from 632 to 904 nm, combining evidence from human and animal-model research. The review described laser treatment as reducing dead-tissue area and increasing activity of this enzyme during early healing, a pattern the authors linked to the enzyme's dual role in both promoting and later calming inflammation during repair. Because much of the cited evidence came from animal-model studies rather than direct clinical trials, the review characterized these findings as a starting point for understanding the mechanism rather than direct proof of a clinical wound-healing benefit.

2012 brought a review from the United States examining the cellular mechanisms behind low-level laser therapy, now more broadly termed photobiomodulation, across red and near-infrared wavelengths from roughly 600 to 1070 nm, for wound healing, pain, inflammation, and swelling. The reviewers described how red and near-infrared light is absorbed inside cells to boost energy production and trigger downstream repair signaling, while noting that different wavelengths and doses have produced inconsistent effects on cell growth in laboratory studies, with some laser settings shown to lower rather than raise cell proliferation. According to the review, the field's therapeutic promise depends on carefully matching wavelength and dose to the target tissue, rather than assuming any laser setting will work equally well.

Wavelengths of 632.8, 670, 692, and 780 to 830 nm were reviewed in 2010 research examining how low-power laser therapy appears to support the tissue-repair process following surgery, drawing on both gum-tissue and skin wound research. The review authors described low-power laser treatment as speeding the pace of healing after surgery and reported pain-relieving and anti-inflammatory effects alongside this, while noting that the precise cellular mechanism behind the effect had not yet been fully clarified. Even so, the reviewers concluded that laser biostimulation appears to meaningfully influence the wound-repair process.

A 2010 review from the United States examined 33 published studies on pulsed low-level light therapy, covering wavelengths from roughly 610 to 956 nm, including 10 studies that tested pulsed light against untreated controls specifically for wound healing, all 10 of which reported a healing benefit. Only 2 studies compared pulsed light directly against continuous-wave light for wound healing, with 1 favoring pulsed light and the other favoring continuous-wave light by a small margin. The review authors concluded that pulsed light appeared to work especially well for wound healing and stroke recovery, though they cautioned that pulse settings were reported too inconsistently across studies to say which frequencies work best.

When researchers reviewed 85 patients’ worth of evidence on low-level laser therapy for chronic wounds, including diabetic foot ulcers, venous leg ulcers, and pressure ulcers, a 2005 study from South Africa covered wavelengths spanning roughly 500 to 1100 nm. The review authors described results for diabetic wound healing specifically as inconclusive, with some studies supportive and others neither supporting nor ruling out a benefit, and called for further research to settle the question.

According to a 2008 review from the United States covering wavelengths from 488 to 1060 nm, researchers found few well-controlled human trials of low-level laser therapy for chronic wounds, particularly venous leg ulcers and pressure ulcers. Most studies showing a healing benefit had been done on cells in laboratory dishes or in animals rather than in patients. One identified controlled trial found no significant effect of helium-neon laser light on chronic venous leg ulcer healing in humans. The reviewers concluded that current evidence does not reliably support low-level laser therapy as an effective treatment for these chronic wounds.

According to a 2002 randomized controlled trial in Poland, researchers tested whether adding 810 nm laser light at a dose of 4 J/cm² per session to standard pharmacological and compression therapy over about 4.5 to 5 weeks could improve healing in 65 patients with venous leg ulcers, compared with a placebo device and standard care alone. All 3 groups saw a significant reduction in ulcer area and length during the study, but the added laser treatment did not produce a significantly better result than the placebo or standard-care-only groups. The researchers concluded that laser stimulation at this dose had no measurable impact on healing beyond standard care.

Researchers in Poland tested laser biostimulation as an add-on to standard drug and compression therapy for venous leg ulcers in a 2001 randomized controlled trial. 49 patients were split into 3 groups, with 1 group additionally receiving 810 nm laser light at a dose of 4 J/cm² per session, a second group receiving a placebo device delivering sham laser therapy, and the third group continuing with standard treatment alone. The added laser therapy did not significantly improve healing beyond what standard pharmacological and compression treatment achieved on its own.