Red Light Therapy and Skin Health
A research overview of red light therapy for skin health
Written for CytoLED.com by Vladimir Heiskanen
Takeaways/highlights:
● Red light therapy has evidence of beneficial effects on skin, both for a number of specific skin disorders, as well as for generalized improvement of skin and reducing signs of skin aging.
● Red light therapy exerts its effects by different mechanisms; compared to therapies like laser resurfacing, which induce mild thermal damage to skin, which can initially cause erythema and other side effects, but will eventually lead to regenerative healing of the skin, and improved appearance of the skin surface. Instead, it alters the metabolism of skin tissue and exerts its effects without such initial damage.
● When one is irradiating the skin, one might simultaneously be activating biological processes that could affect the whole body in a beneficial way. Perhaps these systematic effects of red light could partially explain why exposure to sunlight, containing plenty of red light, has been linked to beneficial health outcomes.
Introduction
Red light therapy (also called photobiomodulation), is a medical and general wellness promoting treatment that has been studied since the 1960s, but has become rapidly more popular during the past 10 years. In our overview article What is Red Light Therapy? we show that red light therapy has shown promise for a variety of diseases, and abundant red light exposure may also be beneficial for general health.
This article focuses on what we know about red light therapy and skin.
Red light therapy has been primarily studied for acne vulgaris and general skin rejuvenation. However, there also exists preliminary research about red light therapy for other skin-related ailments, such as allergic dermatitis, burn scars, erythema, psoriasis, shingles and vitiligo. While our article aims to provide an easy-to-read summary of the subject, it has also been covered in a more detailed and technical manner in these two review articles from 2021:
Light emitting diodes technology-based photobiomodulation therapy (PBMT) for dermatology and aesthetics: Recent applications, challenges, and perspectives
Photobiomodulation: The Clinical Applications of Low-Level Light Therapy
Red light therapy of skin should not be confused with some other light-based skin therapies, such as ablative laser resurfacing, non-ablative resurfacing, fractional resurfacing or intense pulsed light. These other therapies are mostly based on inflicting mild thermal damage to skin, which initially can cause erythema and other side effects, but will eventually lead to regenerative healing of the skin and improved appearance of skin surface. Unlike these treatments, red light therapy is based on using light skin metabolism stimulation without causing any thermal damage.
Red light and skin rejuvenation
It has been previously shown that red light and near-infrared may stimulate the skin to increase collagen synthesis, which can result in increased skin thickness. These effects have been demonstrated in cultured human skin cells, mice and rats (1-4). It has also been shown that red light may protect skin cell cultures against premature senescence induced by hydrogen peroxide (5).
The effects of red light therapy on skin health have been studied in a dozen countries including France, Germany, Korea, the United Kingdom and the United States. The highest quality evidence comes from the five randomized trials testing LED-based devices on skin health. There are also approximately 20 other human studies with lower methodological quality, and a couple of animal trials evaluating the light’s effects on skin collagen synthesis.
The randomized clinical studies have shown generally favourable results for red light, suggesting various beneficial effects such as increased skin smoothness, increased elasticity, reduced wrinkles, nasolabial fold reduction and cheek uplifting (6-8). For example, one split-face study showed a 26% decrease in wrinkle severity on the treated side of the face compared to 20% worsening in wrinkle severity on untreated side (9).
The trials cited above had 32 to 76 participants, and they lasted from 4 weeks to 4 months. The most common irradiation schedule seems to be a daily irradiation lasting from 3 to 20 minutes. The results were obtained in various ways, but usually they were based on both subjective and objective measurements suggesting beneficial effects. For example, one study used a 3D skin analysis camera for the determination of nasolabial fold flattening and a skin scanner device to assess the improvement in skin density (6).
While the study results have been mostly favourable, some trials have also shown modest or zero effect from red light. For example, one study showed no additional benefit from red light therapy on wrinkles treated by non-ablative radiofrequency (10).
Red light and acne
In the treatment of acne, there have been many studies evaluating various wavelengths of light as a therapeutic tool. Intriguingly, for acne treatment there exist studies utilising blue light, red light, near-infrared light and even ultraviolet light.
The reason why blue light has been studied might be related to the fact that the P. acnes bacteria appear to be susceptible to blue light irradiation (11). The effects of red light are supposed to be related to the general skin health-promoting effects that it has. This appears to be the reason why many research groups have been using the combination of both (blue and red) for synergetic effects.
In general, the literature includes a large number of inadequately controlled trials, but also a few well-designed randomized trials. There is one 12-week randomized study with 35 participants, suggesting that a home-use LED device emitting blue and red light decreased inflammatory acne lesions by 77%, and non-inflammatory lesions by 54%, while no improvement was noticed in the placebo group (12). Another randomized study with 28 participants, reported that red light alleviated acne during the 8-week period. A 55 percent reduction in total lesion count was seen in the treatment group, while there was a 19 percent increase in lesions in control group (13).
There is preliminary research suggesting that light-based treatment of acne might have comparable benefits to a pharmaceutical treatment. For example, one randomized trial suggested that combined blue-red light may be superior to blue light alone and more effective than the benzoyl peroxide cream (14). Another study showed that the blue-red light was slightly more effective than salicylic acid peel (15).
Red light and other skin conditions
There are a few preliminary clinical trials, suggesting that a combination of red and near-infrared light, may slightly alleviate radiation dermatitis in radiotherapy patients (16).
There is preliminary evidence that green or red light therapy, could be beneficial for body contouring by inducing small reductions in hip, waist and thigh circumference when compared to sham treatment (17-18).
There are controlled studies suggesting, that red light might mitigate erythema (redness of skin) after ultraviolet irradiation (19) or thermal light therapies, such as intense pulsed light treatment (20) or fractional laser (21).
For atopic dermatitis, there are a handful of animal trials (22-23) and a single-arm human trial, suggesting decreased itching in 79 percent of the patients after the treatment (24).
For burn scars in children, three randomized trials suggest that red or polychromatic light, may improve the scar appearance (25-27). For post-surgical scars, a single clinical trial suggests that red light therapy, may not be effective for improving scar pliability (28).
Psoriasis is an autoimmune skin disease, characterized by “skin plaque” (raised areas of abnormal skin). A case series study with nine patients, showed 60-100% clearance rates with a combination of red and near-infrared light in recalcitrant psoriasis (29). Another study with psoriasis patients, showed improvement in symptoms after either red or blue LED light (30). These studies are not controlled, so additional research efforts are needed for making conclusions regarding the true efficacy.
Vitiligo is a skin condition characterized by pigment loss in certain skin areas. A 2003 study of red light therapy, revealed an at least 50% repigmentation response in 60% of the patients after 8 weeks, which was comparable to a previously treated group which received PUVA therapy (31).
Systemic effects by skin irradiation
Red light irradiation is known to have potential systemic effects on health. In academic texts this is referred to as “remote effects”, “systemic effects” or “abscopal effects”.
There have been several experimental studies suggesting that irradiating one part of body can be beneficial for another body part. Here are some human study results to demonstrate the effect:
Zhevago 2006 (32)
Irradiation of lower back decreased inflammatory markers in blood of study participants
Zhao 2012 (33)
Irradiation of whole body improved sleep in young athletes
Samoilova 2008 (34)
Irradiation of right hand was followed by increased blood flow in left hand
de Sá 2021 (35)
Irradiation of right foot was followed by warming of both feet
Oron 2022 (36)
Irradiation of legs increased CD34+ cells and macrophages in circulating blood
Similarly, the systemic effects have been demonstrated in animal studies:
Johnstone 2014 (37)
Irradiation of back alleviated brain damage in neurotoxin-exposed mice
Park 2021 (38)
Irradiation of ears decreased aortic plaque in rabbits
Chen 2022 (39)
Irradiation of right foot improves the healing of diabetic ulcer in left foot in rats
Silva 2020 (40)
Irradiation of body mitigated insulin resistance in high-fat fed mice
Saliba 2015 (41)
Irradiation of body protected eyes from diabetic complications in mice
So, when one is irradiating the skin, one might simultaneously be activating biological processes that could affect the whole body in a beneficial way. This area of research is still at an early stage however, and it is difficult to get a complete picture of these effects at the current time.
Perhaps these systematic effects of red light, could partially explain why exposure to sunlight; containing plenty of red light, has been linked to beneficial health outcomes, such as lower mortality (42) and a smaller risk of diseases, such as cancer, diabetes, hypertension, multiple sclerosis and vital infections (43-47).
Conclusions
Red light irradiation has shown early promise for a wide range of skin conditions, including acne, skin aging, dermatitis, burn scars, psoriasis and vitiligo. Based on the published findings, it may be feasible to consider red light as a potentially favourable agent for general skin health.
References
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