Red Light Therapy: Safety and Effectiveness Reviewed
By: Amy Niu
Red light therapy (RLT) is a skincare treatment that involves the use of low-wavelength red light to purportedly reduce scars and promote wound healing; reduce stretch marks, wrinkles and fine lines; and decrease incidence of acne [1]. There are many terms used to describe red
light therapy, including but not limited to “low-light laser light therapy” “low-power laser therapy,” “non-thermal LED light,” “soft laser therapy,” “cold laser therapy,” “biostimulation” or “photostimulation,” and “phototherapy” or “photobiomodulation” [1]. According to the Cleveland Clinic, red light therapy is controversial due to doubts about its effectiveness in treating the conditions for which it is promoted.
How does red light therapy work?
Roy (2023) explains that red light therapy involves the use of a photosensitizer, or light-sensitive substance, and exposure to the light wavelength that corresponds to the absorbance of the photosensitizer, thus activating the substance. Red light therapy affects the body’s mitochondria (where energy for a cell is created, thus earning mitochondria the moniker, “powerhouse of the cell”) such that certain cells absorb the light’s wavelengths and use that added energy to work more efficiently and repair and rejuvenate themselves [2].
Safety of red light therapy
Jagdeo et al. (2019) note that the lack of randomized, controlled trials of red light therapy at various different treatment parameters means the safety of red light therapy for clinical use is not well understood. The researchers conducted two randomized, controlled trials of high-fluence (i.e. high-energy) LED red light phototherapy so they could study the safety of such
therapy on human skin, as well as determine the maximum tolerated dose in healthy subjects with diverse racial and ethnic backgrounds.
In both trials, Jagdeo et al. (2019) exposed the nondominant forearms of their test subjects to high-fluence LED red light phototherapy. Control group subjects received mock therapy [3]. In the first trial, test subjects received a maximum recommended starting dose of 160 J/cm2, and subsequent treatment group subjects received stronger doses in increments of 160J/cm2 (e.g. 320 J/cm2 for group 2, 480 J/cm2 for group 3, and so on and so forth) [3]. If one or more treatment group subjects experienced adverse events (i.e. second-degree or higher burning,
blistering, erythema lasting over 24 hours, severe swelling, pain, ulceration, muscle weakness and change in sensation) then the researchers concluded their dose was one level above the maximum tolerable dose and did not increase the dosage [3].
In the second trial, the first group of test subjects received a dose of 480J/cm2, whereas the second group received a dose of 640 J/cm2. If only one subject in either treatment group experienced an adverse event, the researchers gave the same dosage to five new participants [3]. If two or more experienced an adverse event, the researchers concluded their dose was one level above the maximum tolerable dose [3].
Jagdeo et al. (2019) concluded that it is safe for people of all different races and ethnicities to receive high-fluence LED red light therapy at any fluence up to 320 J/cm2. Additionally, non-Hispanic Caucasian subjects had a higher maximum tolerated dose of 480 J/cm2 [3]. For subjects who received maximum tolerated doses, some experienced mild adverse events — namely hyperpigmentation and prolonged post-treatment erythema [3].
Effectiveness of red light therapy
Researchers are split on the effectiveness of red light therapy at performing as claimed. On the one hand, Jagdeo et al. (2019) write, “Light emitting diode-red light (LED-RL) phototherapy has been demonstrated to be safe and effective for wound healing, hair regrowth, acne vulgaris, skin rejuvenation, oral mucositis, skin cancers and premalignant skin lesions.” On the other hand, Sun et al. (2020) found that red light therapy delays acute wound healing in mice. They note a discrepancy between their findings and those of previous studies that found that red light therapy helped close chronic venous and diabetic ulcers [4]. They write that red light therapy has a “powerful antimicrobial effect,” and infection is critical to poor wound healing [4]. Therefore, the researchers conclude that it is possible red light therapy promotes chronic wound healing for human subjects by preventing infections that would delay wound healing [4].
Risks of red light therapy
De Pauli Paglioni et al. (2019) examine the potential of red light therapy to increase the risk of tumor recurrences and the growth of a second primary tumor in cancer patients. The studies reviewed by de Pauli Paglioni and colleagues are contradictory, with some suggesting the use of red light therapy by cancer patients can “influence the cellular metabolic processes to the point of stimulating the proliferation of malignant cells and to modulate the tumor microenvironment in order to increase tumor volume” [5]. Other studies suggested that red light therapy can cause the death of malignant cells depending on the dosage, so it cannot activate existing malignant cells [5]. In addition, de Pauli Paglioni et al. (2019) cite two studies that associated the use of red light therapy with improved cancer prognosis. There was no difference in these studies between the treatment group and the placebo group’s tumor recurrence or development of a second primary tumor [5]. This outcome, the researchers write, is attributed to improved quality of life such that the red light therapy enabled patients to follow cancer treatment regimes [5]. The researchers conclude that the studies in their systematic literature review did not have a follow-up period long enough to ensure the long-term safety of red light
therapy technology and that further studies are needed to confirm the present review’s findings [5].
Consumer use of red light therapy
Many tanning salons and medical spas offer red light therapy, so it’s possible to find an establishment near you to undergo the treatment. Additionally, there are red light therapy devices on the market that you can use at home.
Cancer patients may want to act with particular caution when considering red light therapy since, as discussed above, there is no scientific consensus on the therapy’s safety and efficacy for cancer patients.
Works Cited
[1] https://my.clevelandclinic.org/health/articles/22114-red-light-therapy
[2] https://www.mdpi.com/2075-1729/13/1/196
[3] https://onlinelibrary.wiley.com/doi/10.1002/jbio.201960014
[4] https://www.jstage.jst.go.jp/article/jnms/87/3/87_JNMS.2020_87-301/_pdf/-char/en
[5] https://www.sciencedirect.com/science/article/pii/S1368837519301058?via%3Dihub
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