Red Light, Blue Light Therapy

The trend is so popular, you often see it in television shows, commercials and social media feeds. Blue or red light therapy masks are touted as a luxurious way to pamper yourself, unwinding the clock as you lay on a couch scrolling on your phone. Light therapy has a long-documented history. Danish physician Niels Ryberg Finsen began looking at the therapeutic effects of light on skin diseases in the 1890s. He observed that nine days of exposure to red light could minimize smallpox scars. He also discovered that concentrated ultraviolet and blue-violet light could treat a tuberculosis infection of the skin by killing bacteria in the tissue. He won the 1903 Nobel Prize in Medicine for his work.

The Nobel Prize in Physiology or Medicine 1903 was awarded to Niels Ryberg Finsen “in recognition of his contribution to the treatment of diseases, especially lupus vulgaris, with concentrated light radiation, whereby he has opened a new avenue for medical science.” Credit: nobelprize.org

Over the next several decades, advances were made in using violet-blue light to treat acne. From the 1970s to the ‘90s, photodynamic therapy combined with photosensitizing agents were used to treat cancers, precancerous lesions and skin conditions. Dermatologists began using both blue and red light tools in clinics.

In 2002, the U.S. Food and Drug Administration approved the first blue light device for treatment of mild to moderate inflammatory acne, which was the first time a non-drug, non-invasive blue light device had been formally recognized by a regulatory body for acne treatment. Throughout the next decade, products were developed for at-home use.

Dermatology Provider, Amy Snow PA-C primarily uses blue light photodynamic therapy. “The number one reason is to destroy precancerous lesions,” she says. “It’s a light-activated treatment used to clear actinic keratoses and sun damage and some superficial skin cancers.”

The first step is to apply a topical medication or aminolevulinic acid to the damaged skin. It absorbs into the skin for one hour, targeting bad cells. “When the blue light is applied, it reacts to the light and destroys all the irregular cells,” Snow explains. It can be used to treat the face, scalp, hands and arms. A patient spends 16 minutes under the blue light, which may cause a stinging, prickling or burning sensation. Treated areas turn bright red, like a sunburn, which lasts a few days. The patient must avoid the sun for a couple of days. Over the course of the next week, the affected area begins peeling.

“Healthy cells are spared, because it’s only those damaged cells that absorb the chemical. Then it’s destroyed and that causes new cellular epidermal growth, so it’s rejuvenating in that way,” Snow says. It’s a cancer-prevention treatment with a cosmetic upside. Blue light photodynamic therapy restores the epidermis, giving some patients a brighter, smoother look.

Dermatologist Amy Snow uses blue light photodynamic therapy in her practice. Credit: Nic Moye

Blue light vs red light

Blue light stays near the surface of the skin — about 400-470 nanometers — while red light penetrates deeper — 630-700 nanometers — which promotes collagen production and reduces inflammation. Snow says at-home blue or red light masks can help improve skin texture, tone, brightness and poor appearance, but only if used daily. She says they’re not typically used to treat acne any longer because there are more newly developed laser treatments.

Red light benefits

Like blue light therapy, red light can also be used for early-stage treatment of precancerous, early skin cancers, when used in conjunction with a topical drug. It’s also been used to reduce wrinkles. According to Stanford Medicine, there’s evidence that red light treatment has the ability to generate hair growth by widening blood vessels which enables more blood and nutrients to reach hair follicles. Used consistently over several months, red light has spurred regrowth of thinning hair, but when the red light treatment stops, so does the hair growth. It cannot rejuvenate hair growth in areas where hair follicles are dead.

Chasing youth

When customers come to her seeking a fountain of youth, Snow says, “I always try to redirect the conversation. Our main concern should be the health of our skin, because when our skin is really healthy, it reflects the light and we have glowing skin. If you had two people walking toward you down the hallway and one did all these treatments to try to reverse the lines, and one just treated their skin with optimal medical-grade skin care and good procedures that help with skin health, such as PDT, you’re going to notice that person is better looking and more luminous versus the person that may have reduced wrinkles and some tightening, but their skin might not be as rejuvenated.”

Snow recommends Vitamin C in the morning and prescription-strength Retinol at night. “Retinols are still the gold standard for anti-aging and epidermal turnover. They can reduce skin and precancerous lesions just because epidermal repair is so robust with consistent long-term use.”

This article appears in the Source July 23, 2026.