Red Light Therapy for Acne: Scientific Evidence

27 women aged 18 to 45 who received a series of 6 near-infrared laser sessions showed fewer acne lesions afterward, in a 2021 clinical trial in Poland. The light was delivered at 785 nm and 80 mW/cm² in 10-minute sessions, over courses of 42 and 84 days. Counts of both inflamed and non-inflamed lesions appeared to fall significantly, and the amount of oil the skin produced decreased as well. No adverse effects were reported.

Across 31 randomized controlled trials covering 8 skin conditions, a 2018 systematic review assessed LED therapy in dermatology. The trials used wavelengths from 405 to 1072 nm at 1.6 to 350 mW/cm², in sessions from 70 seconds to 27 minutes across 28 to 56 days. According to the review, acne vulgaris was 1 of only 3 conditions to earn a grade B recommendation, alongside herpes simplex and zoster and acute wound healing, while the rest earned grade C or D. The reviewers noted small sample sizes, absent blinding, missing sham comparisons, and widely varied treatment settings across the studies they included.

A split-face design treated 1 cheek with a light-sensitizing drug before the light and left the other cheek with light alone, in a 2009 clinical trial for moderate to severe facial acne. 19 patients had the drug applied to the right cheek for 3 hours, then both cheeks were exposed to narrow-band 635 nm red light at 15 J/cm² in a single session. Acne severity scores fell significantly on both sides at 10 and 20 weeks, and no significant difference appeared between the drug-treated side and the light-only side. The drug-treated side did produce redness and stinging, which the light-only side did not.

27 of 30 patients completed a 2009 clinical trial of low-energy double-pass 1450 nm laser treatment for acne. Those treated received 8 to 12 J/cm² to the face, chest, and back, over courses running from 70 to 280 days. The trial found that average acne grades fell from 3.9 to 1.4, a statistically significant drop. 25 of the 27 tolerated the pain without help, 2 needed a local anesthetic, and side effects were limited to brief, faint redness in a few patients.

A 2008 clinical trial in Italy evaluated red light phototherapy for moderate acne vulgaris. 15 women received 600 to 750 nm light at 20 mW/cm² and 20 J/cm² in 8-minute sessions, given 8 times across 28 days. Acne lesions, the amount of oil the skin produced, and the rate at which the skin lost water all decreased significantly by the end of treatment, and the improvement held at the 3-month follow-up. The authors concluded that red light phototherapy may be an effective, well-tolerated, safe, simple, and inexpensive option for moderate acne.

Symptom scores fell from 3.9 to 1.9 on the treated side of the face, in a 2007 randomized single-blind trial of red light phototherapy alone for acne vulgaris. 28 patients in South Korea had 1 cheek treated with 632.8 nm and 635 to 670 nm light at 6 mW/cm² and 5 J/cm² per session, in 15-minute sessions, twice daily across 56 days, while the other cheek served as the control. Counts of both inflamed and non-inflamed lesions appeared to improve significantly more on the treated side than on the control side. The difference in symptom scores between the 2 sides also reached significance by week 8.

Comparing a low-energy double pass against the conventional high-energy single pass, a 2007 randomized controlled trial tested 1450 nm laser treatment for acne. 6 patients had 1 side of the face treated each way, at 8 to 11 J/cm² for the low-energy pass and 13 to 14 J/cm² for the high-energy pass. The trial found acne counts fell 67% on the low-energy side and 78% on the high-energy side, with improvement rated 2.3 and 2.5 on a 0 to 4 scale. Pain averaged 1.3 out of 10 on the low-energy side versus 5.6 on the high-energy side, which the authors said removed the need for numbing cream.

12 volunteers (5 male and 7 female) with acne on the face, the back, or both took part in a 2004 randomized controlled trial of near-infrared laser light combined with a light-sensitizing dye. Patches of skin measuring 4 by 5 cm were coated with the dye for 5 minutes, then exposed to 803 nm light at up to 50 mW/cm² for 5 to 10 minutes, at 15 or 30 J/cm². 9 of the 12 had a single session and 3 had 8 sessions across 28 days. Only the group given repeated sessions appeared to improve by about 80% a month after treatment. No side effects reported, while a single session had no lasting effect.

In 2021, a systematic review and meta-analysis pooled 13 randomized controlled trials covering 422 participants. It set red light therapy against conventional treatments for moderate to severe acne vulgaris, at wavelengths from 620 to 780 nm. The analysis found no statistically significant difference between red light and those treatments. That held for inflamed lesions, for non-inflamed lesions, and for the combined count of blackheads, pus-filled spots, and pimples. Side effects in the red light groups were mild or absent, and the reviewers cautioned that the pooled trials varied widely and were small.

According to a 2021 review from Qatar, a reasonable body of trial evidence supports low-energy red and near-infrared light for acne, alongside skin rejuvenation, hair loss and body contouring. The review covered wavelengths from 411 to 830 nm at doses from 0.1 to 96 J/cm², in sessions from 6 to 56 minutes. That evidence is weakened by flawed methods, small patient groups, and industry funding, the reviewers reported. They also noted that it is still unclear whether LED sources produce effects that match the laser systems used in most of the better studies.

Published in 2018, this review surveyed LED therapy across skin and hair conditions including psoriasis, eczema, acne, hair loss, actinic keratosis, rosacea, and photoaged skin. It described wavelengths from 400 to 1200 nm at 50 to 200 mW/cm², with 60 J/cm² delivered in 20-minute sessions across 28 days. The authors concluded that LED-based devices are an emerging and safe tool that has entered common practice among dermatologists, while noting that further controlled studies are still needed.

When researchers compared red against infrared light on opposite sides of the face, only the red side improved. This was a 2012 randomized trial in Iran of low-level laser therapy for acne, with 28 patients treated at 12 J/cm² across 42 days, using 630 nm on 1 side and 890 nm on the other. Researchers found that lesion counts on the 630 nm side fell from 27.7 to 6.3, a statistically significant drop, while the 890 nm side moved only from 26.9 to 22.2, which did not reach significance. They concluded that the red wavelength is safe and effective for acne when compared with the infrared one.

No difference in inflamed lesion counts appeared between the treated and untreated sides, in a 2007 randomized split-face trial of 1320 nm laser therapy for acne. 46 patients had 1 half of the face treated 3 times over 21 days, while the other half was left untreated. According to the trial, blackheads decreased significantly on the treated side, though the effect was temporary, and side-by-side photographs showed no significant difference. Most patients rated the treatment as at least mildly helpful for both their acne and their oily skin.

This 2005 review from the United States surveyed the growing number of laser, light, and radiofrequency devices being used for acne vulgaris. It drew on published work rather than new patients, covering 834 patients in total. The devices reviewed ran from 405 to 1540 nm at 25 and 55 mW/cm² and doses from 3 to 320 J/cm², in sessions of 8 to 15 minutes given 3 to 10 times a week. The authors concluded that these devices show promise as a convenient, non-invasive way to clear acne, whether used alone or alongside other treatments. They also stated plainly that long-term data and randomized, blinded studies are still needed.