Source: French to English Tester Published on: 2026-04-29
Source: The Conversation – in French– By Coralie Thieulin, Research Professor in Physics at ECE, PhD in Biophysics, ECE Paris
Red light therapy is now established as a major trend in “beauty tech”.carried by influencersand made accessible through home devices. It is associated with appealing effects such as reduction of signs of aging, improvement of acne, and acceleration of healing. What do we know about the proven or supposed effects of this technology? Is it without risks?
Red light therapy devices intended for the general public most often come in the form of rigid or flexible facial masks, designed to fit the contours of the face. Their price ranges from around one hundred to about one thousand euros. They include a set of light-emitting diodes (LEDs) arranged on their internal surface, emitting visible red light, sometimes combined with near infrared. The user wears this mask for a determined duration (generally a few minutes), in order to uniformly expose the skin to this light. Other formats also exist, such as light panels or portable devices targeting specific areas of the body, but the facial mask remains today the most emblematic form.
This growing interest in red light therapy is based on several complementary factors. On the one hand, technological advances have enabled the miniaturization of LED systems, making their use possible outside of medical offices. In the latter,red light is used especially in dermatology, where it is used for the treatment of acne, wounds, ulcers, and scars. Moreover, these devices are often presented as non-invasive solutions, which contributes to their accessibility and adoption by the general public. Finally, social networks contribute to their visibility by sharing user feedback and usage content, which adds to existing scientific publications and commercial communications.
Let us begin by clarifying what is meant by red light therapy. Also called photobiomodulation, it is based on the use of specific wavelengths, generally between 630 and 660 nm, sometimes extended to the near infrared (approximately 800–900 nm).These wavelengths can penetrate the skinup to the dermis without causing significant heating or damage comparable to UV.
What are the biological effects of photobiomodulation?
At the biological level, photobiomodulation is believed to be linked to several cellular mechanisms that are still under study. The main mechanism mentioned in the research is based on an interaction with the mitochondria (small cellular structures that produce energy – in the form of a molecule called adenosine triphosphate: ATP – from nutrients and oxygen), particularly withthe enzyme cytochrome c oxidase, a key player in the respiratory chain.Several works suggestthat this enzyme acts as a chromophore capable of absorbing red light, leading to changes in its redox state (gain or loss of electrons) and stimulation of metabolism, notably through an increase in ATP production and activation of intracellular signaling pathways.
These processes are accompanied by several biological effects mainly observed in vitro and in animal models. Oneincrease in ATP productionhas notably been measured after exposure to these wavelengths. Furthermore, light appears to modulate oxidative stress, that is to say the imbalance between the production of reactive oxygen species and the antioxidant defense systems of the cell. This imbalance can damage lipids, proteins, and DNA when excessive, but can also play a role as a biological signal at low levels. This process notably involves a controlled production of reactive oxygen species (ROS) and nitric oxide, two molecules involved in cellular signaling pathways. Finally, these biochemical signals activate intracellular cascades (kinases, transcription factors) promotingprocess of tissue repair and regeneration.
Modest effects
These mechanisms are still debated, particularly concerning the exact role of cytochrome c oxidase, whose direct involvement is not unanimously demonstrated. Despite these mechanistic uncertainties, photobiomodulation has been extensively studied clinically, with overall positive but variable results depending on the indications.
In the case of skin aging,several testsreport a slight improvement in fine wrinkles, skin texture, and elasticity after several weeks of treatment. These effects are believed to be related to the stimulation of fibroblasts (basic cells of connective tissues) and the increased production of collagen.A reviewemphasizes that the observed effects are real but heterogeneous and not yet well standardized.
Regarding healing, thedata suggest a potential effect, but the evidence remains incomplete and sometimes contradictory. Red light could be involved in the different phases of tissue repair (inflammation, proliferation, and remodeling) by stimulating the activity of key cells such as fibroblasts and macrophages (immune system cells). It would thus promote collagen production, cell migration, and possibly angiogenesis (formation of new blood vessels from existing vessels), contributing to the reconstruction of damaged tissue. However, theclinical data are heterogeneousÂ: some studies show an acceleration of healing, while others do not find a significant effect.
Finally, in the treatment of acne, red light primarily acts through anti-inflammatory effects and modulation of the activity of the sebaceous glands (located in the skin and involved in the synthesis and secretion of sebum). Studies report a decrease in inflammatory lesions and redness, withoverall moderate resultsandvariables according to protocols. It is often more effective when combined with other light therapies.
A limited level of evidence
Despite encouraging results in several areas, photobiomodulation remains a developing field, with the level of evidence limited by several methodological factors. Many studies are based on small sample sizes, which limits statistical robustness and the generalization of results. Furthermore, the heterogeneity of experimental protocols (exposure duration, light intensity, treatment frequency) complicates comparison between studies and may explain some observed discrepancies.
These methodological limitations contrast with the rapid dissemination of consumer devices (LED masks, panels, portable devices), tovariable and poorly standardized performances. The gap between experimental conditions (controlled parameters, precise doses, medical monitoring) and domestic use can lead to an overestimation of effects, sometimes amplified byoptimistic business speeches.
In summary, photobiomodulation is based on plausible biological mechanisms and experimental and clinical results that are still partially consistent. The level of evidence remains moderate to date, notably due to the limited number of large randomized controlled trials and the heterogeneity of protocols. The available data suggest potential effects in several dermatological indications, but their magnitude and reproducibility vary according to the conditions of use. This technology is thus situated in a developing field of research, requiring additional standardized studies to specify its indications and optimal parameters.
In this context, adverse effects remain rare but possible, mainly in the form of transient skin irritations or eye discomfort in case of misuse. Current data do not highlight any major toxicity at the parameters used in photobiomodulation, but the effects of prolonged or unsupervised use remain insufficiently documented. Some situations can alsorequire special precautions, notably in people with increased sensitivity to light or specific dermatological conditions.
The use of commercial red light devices should therefore be considered with caution, especially outside a medical setting. It is recommended to seek medical or dermatological advice in case of use for therapeutic purposes. Furthermore, the devices available on the market vary in quality: it is important to check parameters such as the wavelength (generally 630–660 nm for red), the emission power, as well as the presence of safety certifications.
Coralie Thieulin does not work for, advise, own shares in, or receive funds from any organization that could benefit from this article, and has declared no other affiliation than her research institution.
–ref. Red light masks: what does science say about their effectiveness? –https://theconversation.com/masks-with-red-light-what-does-science-say-about-their-effectiveness-281373