Red Light Therapy Explained: Benefits, Science, and Safety

Have you ever wondered if red light therapy actually works? Using natural light to treat skin diseases, called heliotherapy, has been around for a very long time, dating back to ancient Egypt, India, and Greece. Modern light therapy, using artificial light, started in the late 19th century, but saw a rise in popularity after Niels Finsen received the Nobel Prize for Medicine in 1903 for treating lupus vulgaris using concentrated ultraviolet light.

Today, many products focus on red light therapy, especially in the at-home setting. These devices work on the principle of photobiomodulation, the exposure of skin to light sources primarily in the red and near-infrared, administered through low-level lasers or LED devices. Photoacceptors in the skin receive the photons, particularly cytochrome c oxidase in mitochondria, triggering downstream reactions. The effects specific to dermatology include treatment of alopecia and acne, and skin rejuvenation.

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Alopecia (hair loss)

Alopecia is the medical term for hair loss, and it can occur on the scalp or the entire body, and it can be temporary or permanent. Photobiomodulation has been found to treat alopecia for both males and females, stimulating hair regrowth and increasing hair density and length. The treatments done in these studies used wavelengths of 630-800 nm, with 10-25 minute treatments administered 2-3 times per week for 16-24 weeks. Hair regrowth may be increased due to photobiomodulation stimulating the release of paracrine growth factors from dermal papilla cells. Mild side effects have been reported, including scalp irritation, itchiness, and tenderness.

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Acne

Photobiomodulation has also been shown to reduce facial acne vulgaris, resulting in fewer lesions and less inflammation. Studies suggest it may contribute to the destruction of the bacteria Cutibacterium acnes through porphyrin activation, which has an antimicrobial effect. In one study, each participant had half of their face treated with red light (wavelength of 635-670 nm) for 15 minutes twice a day for 8 weeks, while the other side was not treated. The treated side resulted in a 55% reduction of noninflammatory and inflammatory lesions, and the control side experienced a 19% increase in lesion count. Wavelengths for acne treatment range from 620-750 nm with a fluence ranging from 12-37 J/cm², with 10 minute treatments done 3-5 times per week for a minimum of 4 weeks. Some reported side effects were exfoliation, burning, pain, and pigmentation.

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Skin rejuvenation

Red light therapy promotes the production of growth factors and proteins that stimulate collagen and elastin. Clinical studies have demonstrated that photobiomodulation improves facial skin hydration, elasticity, density, roughness, and tightness. It can also improve the appearance of photodamage, with clinical grading scores showing a 25% to 50% improvement in photoaging scores in 52% of participants. Wavelengths used for skin rejuvenation range from 620-1072 nm with 10-20 minute treatments administered biweekly to daily for 4-16 weeks. Some mild side effects include redness and mild pain.

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Some precautions

Bright LEDs can be uncomfortable and potentially risky for eyes, so it is important to use appropriate eye protection and follow device instructions. Some medications can increase light sensitivity, in which case it is important to consult with your doctor beforehand. Furthermore, red LEDs don’t cancel out UV damage, so sunscreen and daily sun protection is still important for prevention and protection.

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Tips for choosing an at-home product

Outcomes depend on parameters such as wavelength, dosage, irradiance, session length, and treatment frequency. When looking for an at-home device, make sure there are clear wavelength and energy specifications that match what results you are trying to achieve. Wavelength is the most important specification, so look for devices that clearly list wavelengths rather than just saying “red light”. Furthermore, pay attention to irradiance, which refers to how much light is delivered on a specific area. A good range would be between 25mW/cm² and 120mW/cm². Fluence is calculated with irradiance and time, and is expressed in J/cm². Specific fluence should be tailored to the treatment you are trying to achieve. Avoid products with bold claims, and stick to FDA-cleared devices and consistent schedules.

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Conclusion

Overall, red light therapy builds on a long history of using light for healing and has studies suggesting its ability to treat alopecia, reduce acne, and improve skin hydration. While research shows promising benefits, results depend on proper wavelength, fluence, session length, and frequency. Red light therapy should be used as a supportive tool, with proper safety measures such as continued sunscreen application and eye protection remaining important. With regular use and FDA-cleared devices, red light therapy can be a useful and promising addition to skincare routines.

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Citations

Davis, M. (2024, April 24). How to Choose a Red Light Therapy Device? (7 Key Features). Hue Light USA. https://huelightusa.com/how-to-choose-red-light-therapy-device/

Mineroff, J., Jalal Maghfour, Ozog, D. M., Lim, H. W., Kohli, I., & Jagdeo, J. (2024). Photobiomodulation CME Part II: Clinical Applications in Dermatology. Journal of the American Academy of Dermatology, 91(5), 805–815. https://doi.org/10.1016/j.jaad.2023.10.074

Ruscoe, G. (2023). The History of Light Therapy | Environmental Physiotherapy Asscociation. Environmentalphysio.com. https://environmentalphysio.com/2024/04/18/the-history-of-light-therapy/