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ChenDermatologist
Dr. Chen Yi-Jia · Dermatology Notes
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Patient guide · Medical lasers Based on 2022 German S2k · Updated 2026-05-05

Dermatologic laser comparison
Wavelength × indication × evidence strength

Lasers are not the more expensive or newer the better — different wavelengths target different chromophores (pigment, hemoglobin, water), and picking the wrong one can be ineffective or leave scars. Following the 2022 German Dermatology Society S2k laser guidelines (Paasch et al., JDDG), this article maps 12 commonly used wavelengths against 30+ indications into an evidence-based match table.

Note:This article is a patient-education summary. Actual laser selection must be done by a specialist based on individual skin type (Fitzpatrick I–VI), lesion depth, and prior treatment response. Even at the "same wavelength", outcomes differ significantly across manufacturers, pulse widths, and energy settings. This guide covers only wavelength-level indications.
Evidence-strength legend

↑↑ Strongly recommended Most informed patients would choose this treatment; efficacy and safety are well supported
↑ Recommended Most would choose it, but individual evaluation is still needed
○ May consider Evidence is limited or risk-benefit is unclear; consider case-by-case
↓ Not recommended Most would not choose this treatment; efficacy is poor or risk is high

How to Choose a Laser — Chromophore-Based Logic

Lasers work by selective photothermolysis: different wavelengths are absorbed by different chromophores (melanin, hemoglobin, water, tattoo ink), converting light to heat to selectively destroy targets while sparing surrounding tissue.

  • Melanin: absorbs 532-1064 nm; shorter wavelength = stronger absorption but shallower penetration
  • Hemoglobin / oxyhemoglobin: peaks at 418, 542, 577 nm; clinically PDL (585-595 nm), KTP (532 nm), Nd:YAG (1064 nm)
  • Water: strong absorption at 1450, 1927, 2940, 10600 nm — basis of fractional / ablative resurfacing
  • Tattoo pigments: color-specific absorption — black/blue/green at 1064/755/694; red/yellow at 532

12 Common Wavelengths in Clinical Practice

WavelengthLaser typePrimary uses
308 nmExcimerVitiligo, psoriasis, mycosis fungoides
532 nmKTP / frequency-doubled Nd:YAGSuperficial pigment, telangiectasia, cherry angioma
585-595 nmPulsed dye laser (V Beam)Hemangioma, port-wine stain, rosacea redness, scars
694 nmRubyDeep pigment, tattoos (black/blue/green), nevus of Ota
755 nmAlexandriteDeep pigment, hair removal, picosecond (PicoSure)
800-980 nmDiodeHair removal (suitable for darker skin)
1064 nmNd:YAGDeep pigment, deep vessels, tattoo, hair removal, picosecond
1450-1565 nmErbium glass / diodeNon-ablative fractional, acne scars, photoaging
1927 nmThuliumNon-ablative fractional, superficial pigment, melasma
2940 nmEr:YAGResurfacing, nevus, syringoma, CO₂ alternative
10600 nmCO₂Resurfacing, fractional, nevus, warts, rhinophyma
IPLPulsed light 590-1200 nmBroad: superficial pigment, telangiectasia, hair removal, rosacea

Picosecond vs Q-switched (nanosecond): same wavelengths but picosecond (10⁻¹² s) pulse uses photomechanical effect instead of pure heat — better safety profile, faster recovery. Generally similar efficacy for many indications, picosecond costs more.

Indication-Based Recommendations (German S2k 2022)

Pigmented lesions

  • Ephelides / lentigines / café-au-lait: Q-switched 532/694/755 nm picosecond/nanosecond ↑↑
  • Nevus of Ota / ABNOM (dermal pigment): Q-switched 755/1064 nm ↑↑; IPL NOT recommended (insufficient depth)
  • Melasma: low-energy Q-switched 1064 nm or 1927 nm ONLY; aggressive laser triggers PIH; ablative resurfacing strongly NOT recommended
  • Melanocytic nevus: NOT recommended per S2k — risk of masking melanoma; only specialist exception

Tattoo Color-Wavelength Match

Color1064 nm755 nm694 nm532 nm
BlackExcellentExcellentExcellentPoor
BlueGoodGoodGoodPoor
GreenGoodGoodGoodPoor
RedPoorPoorPoorExcellent
YellowPoor—PoorGood

Black tattoos: 1064 nm picosecond Nd:YAG most common. Multicolor: rotate wavelengths over 8-15 sessions, 6-8 weeks apart. IPL NOT recommended for tattoo removal.

Vascular lesions

  • Telangiectasia: PDL ↑↑, KTP 532 ↑↑, Nd:YAG 1064 ↑↑, IPL ↑↑
  • Rosacea persistent erythema: IPL ↑↑, PDL ↑
  • Port-wine stain: PDL ↑↑ (1st-line); Nd:YAG for thickened/nodular transformation
  • Cherry angioma / spider angioma: KTP, Nd:YAG long-pulse, PDL all ↑↑

Scars

  • Atrophic scars (acne): Fractional 1540-1550 nm non-ablative ↑↑ (less downtime); Fractional CO₂ ↑↑ (best results, 5-7 day recovery)
  • Hypertrophic / Keloid: PDL for redness ↑; NOT recommended: ablative fractional on active keloid
  • Burn scars: PDL + fractional + LADD (laser-assisted drug delivery) is the modern combination

Hair removal

  • Fitzpatrick I-III: Alexandrite 755 nm ↑↑
  • Fitzpatrick I-IV: Diode 800-980 nm ↑↑
  • Fitzpatrick IV-VI: Nd:YAG 1064 nm ↑ (safest for deeper skin)
  • IPL multi-wavelength ↑↑ for I-IV

Critical Warnings

  • Pigmented lesions undiagnosed: NEVER laser without dermatology assessment first; risk of masking melanoma
  • Recent isotretinoin use: traditional 6-month wait for ablative laser; modern guidelines 1-3 months for non-ablative
  • Fitzpatrick V-VI: 1064 nm safest; 532/694/755 carries PIH risk
  • Recent sun exposure: avoid 2-4 weeks before treatment
  • Active infection (herpes, inflammation): defer treatment
  • Pregnancy: insufficient safety data — defer
  • Cyclosporine: avoid concurrent UV / 308 nm excimer

How to Discuss Laser with Your Doctor

  1. "What is my diagnosis? Pigment, vessel, or scar?" — Confirm the problem first
  2. "What wavelength options exist? What's the evidence?" — From 1st-line to alternatives
  3. "How many sessions? Interval? Side effect risks?" — Realistic expectations

Beware overhyped "single laser fixes everything" marketing. The 2022 German S2k laser guideline lists 30+ indications across 12 wavelengths, each with its own evidence strength. Choose dermatology-trained physicians who honestly explain trade-offs.