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Light-Based Treatments and Devices

PHOTOBIOMODULATION (LOW LEVEL LASER LIGHT THERAPY) 38309304, 38307144​​

Introduction

Definition(s)

  • PBM is a light therapy using red (620–700 nm) and near-infrared (700–1440 nm) light delivered through low-level lasers or LEDs.

  • Watts = joules/second

  • Joules = unit of energy

  • Fluence = joules/area

Mechanism of Action

  • Light interacts with photoacceptors in the skin (mainly COX in mitochondria) - this is contrast to lasers which target chromophores (melanin, heme, opsin)

  • Biological effects include changes in ATP, reactive oxygen species, nitric oxide levels, and calcium.

  • Modifies gene expression, cellular proliferation, and inflammatory pathways.

Penetration Depths

  • 633 nm RL: 1-3 mm

  • 810 nm NIR: 2-10 mm

  • 1072 nm NIR: 5-10 mm

Conditions Treated and Treatment Notes

Cancer Therapy Side Effects (Radiation dermatitis, mucositis, lymphedema)

  • Wavelength: 808–905 nm or red light (620–670 nm).

  • Treatment Course: 1–12 minutes/session immediately after radiation therapy; total duration varies based on condition (e.g., daily treatments for several weeks).

  • Effects: Reduces inflammation, erythema, pain severity, and lymphedema.

Alopecia (Androgenic alopecia, alopecia areata)

  • Wavelength: 630–800 nm.

  • Treatment Course: 10–25 minutes/session, 2–3 times per week for 16–24 weeks.

  • Effects: Stimulates hair growth, increases density, and prolongs the anagen phase - proposed mechanism is by stimulating release of paracrine growth factors from dermal papilla cells. 

  • Studies:​​

Meta-analysis of photobiomodulation for the treatment of androgenetic alopecia. J Dermatolog Treat. 2021. PMID: 31746251.

Photobiomodulation Therapy With Different Wavebands for Hair Loss: A Systematic Review and Meta-Analysis. Dermatol Surg. 2022. PMID: 35510860.

  • Systematic review and meta-analysis that showed that ultraviolet light was effective in treating AA, red light was effective in treating AGA, and infrared light was effective in treating both AA and AGA.

Clinical Safety and Efficacy of Dual Wavelength Low-Level Light Therapy in Androgenetic Alopecia: A Double-Blind Randomized Controlled Study. Dermatol Surg. 2025. PMID: 39679573.​

  • This double-blind randomized controlled trial evaluated the efficacy of three LED caps (REVIAN LED “smart cap”) emitting red (625/660 nm), blue (425 nm), or both wavelengths versus a sham device in treating androgenetic alopecia. After 16 weeks of daily 10-minute treatments, the pooled active treatment groups showed a statistically significant net increase of 28.5 hairs/cm² compared to sham (p = 0.033), with blue light (Cap 102) yielding the highest numeric hair count gain and red light (Cap 101) achieving the best cosmetic appearance by physician assessment. However, by week 26, hair gains were not maintained, likely due to poor compliance, and individual cap comparisons were underpowered due to high exclusion rates.

Ulcers (Diabetic ulcers, chronic wounds)

  • Wavelength: 630–980 nm.

  • Treatment Course: 2–20 minutes/session, 2–7 times per week for at least 4 weeks.

  • Effects: Accelerates wound healing, decreases inflammation, and reduces pain.

Herpes Simplex Virus (HSV)

  • Wavelength: 670–1072 nm.

  • Treatment Course: 2–5 minutes/session, 2–3 times per week during outbreaks.

  • Effects: Speeds up lesion healing, reduces symptoms, and prevents recurrences.

Acne Vulgaris

  • Wavelength: 620–750 nm.

  • Treatment Course: 10 minutes/session, 3–5 times per week for a minimum of 4 weeks.

  • Effects: Reduces lesion count, inflammation, and sebum levels.

​​

Home-Based​

At-Home LED Devices for the Treatment of Acne Vulgaris: A Systematic Review and Meta-Analysis. JAMA Dermatol. 2025. PMID: 40042878.

  • Overview; Systematic review & meta-analysis of RCTs including 6 trials (216 participants, ages 12–50, mild–moderate acne) looking at home / portable blue (414–445 nm), red (630–670 nm), or combination red+blue LED systems

  • Key Findings

    • Overall efficacy:

      • Inflammatory lesions: 45% reduction (95% CI, 25–66%)

      • Noninflammatory lesions: 48% reduction (95% CI, 18–77%)

      • IGA: 46% improvement (95% CI, 29–62%)

    • Safety: No severe adverse events. Mild dryness, erythema, or discomfort in some patients.

  • Most Effective Device Type

    • Combination Red + Blue LED Devices

      • Showed the largest and most consistent improvements compared to blue-only or red-only.

      • Example: Papageorgiou et al. 2000 (415 nm blue + 660 nm red) → 15 min daily × 12 weeks; yielded significant lesion clearance vs white light control.

      • Kwon et al. 2013 (420 nm blue + 660 nm red; home-use mask, 5 min twice daily × 4 weeks) → strong clinical and histologic improvement.

  • Effective Device Parameters (from included RCTs)

    • Wavelengths: Blue ~415–445 nm + Red ~630–660 nm

    • Fluence ranges:

      • Blue: ~4–18 J/cm² per session (depending on device)

      • Red: ~2–6 J/cm² per session (reported for some devices)

    • Treatment protocol:

      • Daily or twice daily use (5–15 minutes/session)

      • Duration: 4–12 weeks

    • Cumulative dose: Typically 100–400 J/cm² total over a course (lower than office devices, but effective with frequent use).

​

Phototherapy with blue (415 nm) and red (660 nm) light in the treatment of acne vulgaris. Br J Dermatol. 2000.  PMID: 10809858.

  • Device Parameters

    • Device: Custom fluorescent lamp fixtures (Osram Sylvania, Brussels, Belgium)

    • Blue light: 415 nm, irradiance 4.23 mW/cm², 15 min/session → ~3.8 J/cm² per session; Red light: 660 nm, irradiance 2.67 mW/cm², 15 min/session → ~2.4 J/cm² per session

    • Distance: 25 cm from skin

    • Total dose (12 weeks): ~320 J/cm² (blue) and ~202 J/cm² (red)

  • Treatment Protocol

    • Patients: 107 with mild–moderate acne (age 14–50, both sexes)

    • Randomization: Four groups – blue light, mixed blue+red light, cool white light (control), or 5% benzoyl peroxide cream

    • Treatment schedule:

      • Light groups: Daily 15-minute self-administered sessions for 12 weeks

      • BPO group: Applied daily for 12 weeks

  • Results

    • Inflammatory lesions:

      • Blue+red light: 76% mean improvement (95% CI, 66–87%)

      • Blue light: ~63% improvement (not significantly different at week 12)

      • BPO: Inferior to blue+red at weeks 8 and 12

      • White light: consistently inferior (p < 0.001 at all time points)

    • Comedones:

      • Blue+red: 58% mean improvement (95% CI, 45–71%)

      • Better than blue light or BPO, though not statistically significant

    • Adverse effects: Minimal; occasional acne flare, dryness/itching, mild rash, or headache (all transient; no severe ev

 

 
Device Comparison

  • Papageorgiou et al., 2000 (Br J Dermatol, 10809858)

    • Irradiance: Blue 4.23 mW/cm², Red 2.67 mW/cm²

    • Fluence per session: Blue ~3.8 J/cm², Red ~2.4 J/cm² (15 min daily)

    • Recommended protocol: 15 min daily × 12 weeks

    • Total dose: Blue ~320 J/cm², Red ~202 J/cm²

  • Celluma FACE

    • Irradiance: Not clearly reported (back-calculated ~3–4 mW/cm²)

    • Fluence per session: ~5.2–7.0 J/cm² (30 min at 1″, both wavelengths reported combined)

    • Recommended protocol: 2–3×/week, 30 min (manufacturer); daily use needed to match Papageorgiou

    • Total dose: ~62–84 J/cm² (if 2×/week × 12 weeks); ~218–294 J/cm² (if daily × 12 weeks)

  • DRx SpectraLite FaceWare Pro

    • Irradiance: ~60 mW/cm² (independent estimate from online reports, not the FDA 510k; not manufacturer-confirmed)

    • Fluence per session: ~10.8 J/cm² (based on assumption of irradiance above, and treatment duration of 3 min daily)

    • Recommended protocol: 3 min daily (auto shutoff)

    • Total dose: estimated ~454 J/cm² (if daily × 12 weeks)

​

In-Office

A Comparative Study Between Once-Weekly and Alternating Twice-Weekly Regimen Using Blue (470 nm) and Red (640 nm) Light Combination LED Phototherapy for Moderate-to-Severe Acne Vulgaris. Lasers Surg Med. 2021. PMID: 33538345.​​

  • Device Parameters

    • Device: Soli‐Tone 2500 LumiFacial® (Silhouet‐Tone, Canada)

    • Blue light: 470 nm, 89 mW/cm², 15 min/session (80 J/cm² per session); Red light: 640 nm, 84 mW/cm², 15 min/session (80 J/cm² per session))

    • Distance: 2 inches from skin

  • Treatment Protocol

    • 30 patients with moderate–severe acne (skin types III–V)

    • Group 1: Alternating blue and red light, twice weekly, 3 days apart (4 sessions of each, 8 total in 4 weeks)

    • Group 2: Once weekly, blue and red light consecutively on same day (also 4 sessions of each, 8 total in 4 weeks)

    • Total dose: ~320 J/cm² each wavelength over 4 weeks (4 sessions each)

    • No concurrent acne therapy allowed

  • Results

    • Both regimens significantly improved inflammatory lesions, not noninflammatory ones.

    • No statistical difference between once‐weekly and twice‐weekly regimens.

    • Improvement persisted up to 8 weeks post‐treatment; mild transient erythema only side effect.

    • Authors suggest once‐weekly may improve compliance without reducing efficacy

 

The efficacy of blue light versus the combination of blue and red light therapy in the treatment of acne vulgaris. Photodermatol Photoimmunol Photomed. 2021. PMID: 34042223.​

  • Device Parameters

    • Device: Waldmann (Germany)

    • Blue light: 415 nm, 48 J/cm²; Red light: 633 nm, 96 J/cm² (study did not provide session time and irradiance not specified, so cannot be calculated)

    • Both applied to half the face in split‐face design

  • Treatment Protocol

    • 33 patients, 18–35 yrs, mild–moderate acne

    • Both hemifaces irradiated with blue light, then one side also received red light

    • Sessions: Twice weekly for 4 weeks (total 8 sessions), followed up for 12 weeks​

    • Total dose: 192 J/cm² (blue) + 384 J/cm² (red) over 4 weeks (4 sessions each)

    • Eye protection and standard skincare (cleanser + SPF 50 sunscreen) required

  • Results

    • Combination blue + red light achieved greater improvement (68.3% at week 12, 70% at week 16) vs. blue light alone (~51%).

    • Improvement was significant at weeks 4 and 8 (p < 0.05).

    • Side effects: minimal (mild erythema, transient burning, pruritus).

    • Conclusion: Blue + red light is more effective than blue light alone due to synergistic antibacterial + anti‐inflammatory effects.

​

Red light phototherapy alone is effective for acne vulgaris: randomized, single-blinded clinical trial. Dermatol Surg. 2007. PMID: 17903156.

  • Device Parameters

    • Device: Softlaser SL30 (Beurer GmbH, Germany)

    • Red light: 635–670 nm

    • Irradiance: 6 mW/cm²

  • Treatment Protocol

    • 28 subjects (split‐face design, mild–moderate acne)

    • One side treated, other side control

    • Sessions: 15 minutes, twice daily for 8 weeks (very high frequency, home-use device)

    • Total dose: 604.8 J/cm² over 8 weeks

    • Follow-up: up to 8 weeks post-treatment

  • Results

    • Significant improvement in inflammatory and noninflammatory lesions on treated side vs. control.

      • Noninflammatory: 59% reduction vs. +3% on control

      • Inflammatory: 66% reduction vs. +74% increase on control

      • Total lesions: 55% reduction vs. +19% increase on control

    • VAS scores also improved significantly (3.9 → 1.8 vs. 3.9 → 2.9).

    • Effect waned after stopping therapy: most patients relapsed within 8 weeks post-treatment.

    • Side effects minimal (1 transient burning case).

​

Skin Rejuvenation (Improvement of elasticity, hydration, and photodamage)

  • Wavelength: 620–1072 nm.

  • Treatment Course: 10–20 minutes/session, biweekly to daily for 4–16 weeks.

  • Effects: Enhances collagen production, reduces wrinkles, and improves skin tightness.

Wounds and Scars

  • Wavelength: 630–830 nm.

  • Treatment Course: 1–10 minutes/session, 3–4 times per week for a minimum of 1 week.

  • Effects: Promotes healing phases, reduces scar thickness, and improves pliability.

PBM in Skin of Color

  • Patients with darker skin may experience increased sensitivity to visible light, resulting in post-inflammatory hyperpigmentation.

  • Recommendations:

    • Start with conservative dosing and increase parameters gradually.

    • Begin at 50% of manufacturers’ recommended settings and monitor for adverse effects​​​

External Medicine

 Conceived 2016

DISCLAIMER: This website is a collection of primary literature and the opinions of the website creators on that literature.  It is not intended to be used for the practice of medicine or the delivery of medical care in the absence of other appropriate credentials (like a medical degree).  Discuss any information with your doctor before pursuing treatments mentioned on this site.  

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