Safety of light emitting diode‐red light on human skin: Two randomized controlled trials

Abstract

Therapeutic applications of light emitting diode‐red light (LED‐RL) are expanding, yet data on its clinical effects are lacking. Our goal was to evaluate the safety of high fluence LED‐RL (≥160 J/cm2). In two phase I, single‐blind, dose escalation, randomized controlled trials, healthy subjects received LED‐RL or mock irradiation to the forearm thrice weekly for 3 weeks at fluences of 160‐640 J/cm2 for all skin types (STARS 1, n = 60) and at 480‐640 J/cm2 for non‐Hispanic Caucasians (STARS 2, n = 55). The primary outcome was the incidence of adverse events (AEs). The maximum tolerated dose was the highest fluence that did not elicit predefined AEs. Dose‐limiting AEs, including blistering and prolonged erythema, occurred at 480 J/cm2 in STARS 1 (n = 1) and 640 J/cm2 in STARS 2 (n = 2). AEs of transient erythema and hyperpigmentation were mild. No serious AEs occurred. We determined that LED‐RL is safe up to 320 J/cm2 for skin of color and 480 J/cm2 for non‐Hispanic Caucasian individuals. LED‐RL may exert differential cutaneous effects depending on race and ethnicity, with darker skin being more photosensitive. These findings may guide future studies to evaluate the efficacy of LED‐RL for the treatment of various diseases.

Light emitting diode‐red light for reduction of post‐surgical scarring: Results from a dose‐ranging, split‐face, randomized controlled trial

“…Adverse events (AEs) included treatment-site erythema, hyperpigmentation, and blistering, all of which were mild and resolved without permanent sequelae [38]. We concluded that LED-RL is safe up to 480 J/cm 2 and may exert differential cutaneous effects depending on race and ethnicity, with darker skin being more photosensitive [38].…”

“…The LED-RL treatment device emitted visible red light (633 ± 6 nm) at a power density of 360.2 W/m 2 at room temperature and a distance of 10 mm from the skin surface [40,42]. The mock treatment device simulated the LED-RL treatment device (i.e., had the same physical components and thermal output) but did not emit red light [38]. The use of mock phototherapy controlled for environmental factors that may affect wound healing, such as ambient light and temperature [35].…”

“…Patients recorded AEs during the 3 week treatment period in a home diary. Common expected post-treatment effects, including warmth, erythema and edema, were not considered AEs unless they were prolonged (i.e., lasting more than 24 hours) [38].…”

“…Prior to our studies on the anti-fibrotic properties of LED-RL, limited data existed regarding red light photobiomodulation of dermal fibroblasts. In two phase I, dose escalation, randomized controlled trials (Safety Trial Assessing Red-light on Skin [STARS 1 and STARS 2], n = 115), we evaluated the safety and tolerability of LED-RL administered at fluences up to 640 J/cm 2 on normal skin [38]. Adverse events (AEs) included treatment-site erythema, hyperpigmentation, and blistering, all of which were mild and resolved without permanent sequelae [38].…”

“…In two phase I, dose escalation, randomized controlled trials (Safety Trial Assessing Red-light on Skin [STARS 1 and STARS 2], n = 115), we evaluated the safety and tolerability of LED-RL administered at fluences up to 640 J/cm 2 on normal skin [38]. Adverse events (AEs) included treatment-site erythema, hyperpigmentation, and blistering, all of which were mild and resolved without permanent sequelae [38]. We concluded that LED-RL is safe up to 480 J/cm 2 and may exert differential cutaneous effects depending on race and ethnicity, with darker skin being more photosensitive [38].…”