Red vs Blue vs Green Light Therapy: What Each Color Actually Does
Walk into any med spa and you'll see panels glowing red, beds flashing blue, maybe some green mixed in. Most people pick whatever looks coolest or trust the front desk to choose. But here's the thing—each wavelength does something fundamentally different at the cellular level.
The Basic Science (Without the PhD)
Light therapy works because your cells have photoreceptors that respond to specific wavelengths. Think of it like radio frequencies—each station picks up a different signal. Your mitochondria, skin cells, and even bacteria all tune into different parts of the light spectrum.
Wavelength is measured in nanometers (nm). The visible spectrum runs roughly 380-700nm, with infrared starting above that. Color determines depth of penetration and which cellular processes get triggered.
Red Light (630-660nm): The All-Rounder
Red light is the workhorse of light therapy. It penetrates about 2-3mm into skin, reaching the dermis where collagen lives.
What it does:
- Stimulates collagen and elastin production
- Increases ATP (cellular energy)
- Improves blood circulation
- Accelerates wound healing
- Reduces fine lines over time
Best for: General anti-aging, skin rejuvenation, surface-level healing, anyone wanting healthier-looking skin.
Most studies showing skin benefits use this range. If you're only doing one type of light therapy, red is probably it.
Near-Infrared (810-850nm): The Deep Penetrator
NIR is invisible to the human eye but penetrates deepest—up to 4-5cm into tissue. This reaches muscles, joints, and even bone.
What it does:
- Reduces inflammation deep in tissue
- Speeds muscle recovery
- Supports joint health
- May benefit brain function (through the skull)
- Accelerates healing of deeper injuries
Best for: Athletes, chronic pain, joint issues, post-workout recovery, anyone dealing with inflammation below the skin surface.
Many professional panels combine red and NIR because they complement each other—red handles the surface while NIR goes deep.
Blue Light (415-455nm): The Bacteria Killer
Blue light doesn't penetrate far—just the epidermis. But it doesn't need to for its main job: destroying acne-causing bacteria.
What it does:
- Kills P. acnes bacteria (the main acne culprit)
- Reduces active breakouts
- Has mild anti-inflammatory effects
- May help regulate oil production
Best for: Active acne, oily skin, people who've tried everything else for breakouts.
One caveat: blue light works on bacterial acne, not hormonal or cystic acne. If your breakouts are driven by hormones, blue light alone won't solve it.
Green Light (520-560nm): The Calming Specialist
Green sits in the middle of the spectrum. It's less researched than red or blue but shows promise for specific issues.
What it does:
- May reduce hyperpigmentation and dark spots
- Calms skin and reduces redness
- Some evidence for migraine relief
- Generally soothing effect
Best for: Sun damage, uneven skin tone, melasma, sensitive skin that reacts to stronger wavelengths.
The research on green is thinner, so manage expectations. It's often used in combination with other colors rather than standalone.
Yellow/Amber Light (570-590nm): The Redness Reducer
You'll see this in some multi-wavelength panels. It targets surface-level concerns without going deep.
What it does:
- Reduces redness and flushing
- May help with rosacea symptoms
- Supports lymphatic function
- Gentle on sensitive skin
Best for: Rosacea, skin sensitivity, anyone who flushes easily.
How to Actually Choose
Skip the analysis paralysis. Here's the practical version:
| Your Goal | Best Wavelength |
|---|---|
| Anti-aging, wrinkles | Red (630-660nm) |
| Deep muscle/joint pain | Near-infrared (810-850nm) |
| Active acne | Blue (415-455nm) |
| Dark spots, pigmentation | Green (520-560nm) |
| Redness, rosacea | Yellow/Amber (570-590nm) |
| General wellness | Red + NIR combo |
Most med spas offer combination panels that hit multiple wavelengths. These are often the smartest choice unless you have a very specific goal.
What Actually Matters for Results
Wavelength is just one variable. You also need:
- Adequate power density — Cheap panels don't deliver enough energy to trigger cellular changes
- Consistency — Light therapy compounds over weeks, not minutes
- Proper distance — Too far away and you lose intensity
- Clean skin — Lotions and makeup block light absorption
A single session feels nice but changes nothing long-term. Most protocols run 3-5 sessions per week for 8-12 weeks before reassessing.
The Practical Takeaway
Light therapy isn't magic. Red light won't erase 20 years of sun damage in a month. Blue light won't cure hormonal acne. But for the right applications with realistic expectations, these wavelengths do trigger measurable biological changes.
The key is matching the wavelength to your actual goal—not just picking the prettiest color.
