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Does blue light therapy clear acne?
Short answer
Blue light near 415 nm is antibacterial against Cutibacterium acnes and reduces inflammatory lesions in controlled trials. The evidence is weaker than for topical or oral prescription treatment, and most consumer masks emit 460–470 nm rather than the 415 nm the trials used.
What the evidence actually shows
Trials typically report reductions in inflammatory lesion counts over 4–12 weeks. Non-inflammatory comedones respond far less.1
What it does not do
It does not treat cystic or nodular acne, and it does not replace prescription therapy for moderate-to-severe disease.
The dose the trials used
Most protocols use ~415 nm, several sessions weekly, for 4–12 weeks.
The trials behind this grade
| Study | Design | n | Finding | Funding |
|---|---|---|---|---|
| Ablon G. 2018 | Review | — | Blue light around 415 nm is antibacterial against C. acnes; red supports anti-inflammatory effect. | unclear |
Reviewed by Jeff Hobbs · Founder and measurement lead · not a dermatologist · educational information, not medical advice