Red, blue, green: which LED wavelength does what

An RGB LED mask is, optically speaking, three lights in one. The three primary wavelengths — red, green, and blue — each interact with skin differently because they penetrate to different depths and are absorbed by different molecules.

This is a short guide to which does what, and where the published evidence is strongest.

Red — 630 nm

Penetration: Several millimetres into the dermis. This is where collagen-producing fibroblasts live.

Primary mechanism: Absorbed by cytochrome c oxidase in mitochondria. Drives photobiomodulation — increased ATP, signalling cascades that influence fibroblast activity.

Targets: The appearance of fine lines and wrinkles. Skin firmness and elasticity. General skin texture.

Evidence base: Most extensively studied of the three for skin rejuvenation. Wunsch & Matuschka (2014), Lee et al. (2007), and several other controlled trials report measurable improvements in skin texture and collagen density after multi-week protocols.

Blue — 460 nm

Penetration: Stays in the epidermis. Does not reach the dermis.

Primary mechanism: Absorbed by porphyrins inside Cutibacterium acnes (formerly P. acnes) — the bacteria implicated in inflammatory acne. Photoexcitation generates reactive oxygen species inside the bacteria, compromising them.

Targets: Inflammatory acne lesions. Surface-level bacterial load.

Evidence base: Strong for acne treatment. Papageorgiou, Katsambas & Chu (2000) published in the British Journal of Dermatology showed significant reduction in inflammatory acne with blue and red phototherapy over 12 weeks. Goldberg & Russell (2006) reported similar findings with combined blue + red LED.

Blue light does not primarily drive collagen production. Its role is bacterial.

Green — 520 nm

Penetration: Between blue and red. More superficial than red.

Primary mechanism: Less clearly established than red or blue. Green wavelengths have been studied for their action on melanocytes and visible pigmentation. Mechanism may involve both photothermal effects on melanin and modulatory effects on melanocyte activity.

Targets: Uneven pigmentation. The appearance of dark spots and post-inflammatory marks.

Evidence base: Narrower than for red or blue. Green wavelength has been used in dermatological protocols for hyperpigmentation, but most of the strongest pigmentation research uses laser systems (such as Q-switched lasers) rather than LED, and outcomes between the two are not directly equivalent.

Combination modes

Most modern RGB LED masks can fire two or three primary wavelengths simultaneously. Visually, the user sees a different colour. Biologically, the skin receives both wavelengths at once.

• Blue + Red (often called "purple" mode): the most-studied combination for acne, particularly inflammatory acne with residual marks.
• Red + Green (often called "yellow"): combines collagen-stimulating action with surface pigmentation targeting.
• Blue + Green (often called "cyan"): combines antimicrobial action with pigmentation effects.
• All three (often called "white"): the broadest single-session protocol.

Choosing what to use

If your concern is fine lines and skin texture — start with red. If it is active acne — blue, or combined blue + red. If it is uneven tone — green, possibly combined with red. For a general anti-aging routine without a single dominant concern — white mode, or rotating through the protocols.

References

Papageorgiou P, Katsambas A, Chu A. Phototherapy with blue (415 nm) and red (660 nm) light in the treatment of acne vulgaris. British Journal of Dermatology, 2000.

Goldberg DJ, Russell BA. Combination blue (415 nm) and red (633 nm) LED phototherapy in the treatment of mild to severe acne vulgaris. Journal of Cosmetic and Laser Therapy, 2006.

Wunsch A, Matuschka K. A controlled trial to determine the efficacy of red and near-infrared light treatment. Photomedicine and Laser Surgery, 2014.

Redermis is a personal-care device, not a medical device. We make no claim to diagnose, treat, cure, or prevent any condition.