Skip to content
Decision-ready map
• Therapy intent: PBM/laser/LED aims for benefit without harm
• Risk pathway: melanin + higher irradiance/pulsing → unintended heating
• Evidence: higher photosensitivity/thermal injury rates in darker skin
• Clinical levers: dosing protocol, cooling, monitoring, escalation + documentation
(1) What it is
Light-based therapies range from photobiomodulation (PBM; low-level light therapy) to higher-power dermatologic lasers, intense pulsed light (IPL), and ultraviolet phototherapy. They aim to trigger biological effects (pain reduction, wound healing, inflammation control, hair/vascular lesion treatment) by delivering light with defined wavelength(s), irradiance, fluence, pulse structure, exposure time, and beam/spot geometry. The safety and equity issue is that skin pigmentation and related tissue optics can change absorbed energy and local temperature rise, increasing adverse-event risk if protocols are not validated and adapted across skin tones.
(2) Who it helps
This brief is for clinicians who deliver PBM or other light-based therapies and who are responsible for protocol selection, informed consent, and adverse-event management. It also supports clinical governance teams designing SOPs, training, and incident reporting.
(3) What evidence exists
Clinical evidence indicates that adverse events can differ by skin color under certain light-therapy protocols. A 2025 retrospective cohort study in Photodermatology, Photoimmunology & Photomedicine reported self-reported darker skin color was associated with increased photosensitivity during dual-wavelength low-power laser therapy, including higher risk of heating/thermal injury and substantially higher odds of clinically visible thermal injuries (https://doi.org/10.1111/phpp.70042). Broader dermatology literature recognizes higher epidermal melanin increases susceptibility to thermal injury and pigmentary complications in laser/light treatments unless parameters are adapted; a review focused on skin of color emphasizes careful parameter selection and early management (https://doi.org/10.4103/ijdvl.IJDVL_88_17). For IPL, an invited review summarizes complications including burns and pigmentary changes and links prevention to parameter choices (https://doi.org/10.1002/der2.57).
For UV phototherapy, minimal erythema dose (MED) varies across Fitzpatrick types; a 2020 study reports MED correlations with Fitzpatrick type, supporting the clinical need for dose discipline rather than assuming uniform response (https://doi.org/10.1016/j.ad.2019.12.003). PBM dosimetry discussions highlight that “dose” is multidimensional (irradiance, fluence, time, spot size) and that inconsistent reporting undermines safety translation (https://doi.org/10.21037/atm.2016.05.34). Regulatory guidance also exists: FDA’s PBM draft guidance outlines expectations for testing and labeling for PBM devices (FDA webpage).
(4) Translation barriers
First, protocols are often incompletely reported (missing irradiance at tissue, spot size, duty cycle, distance, cooling), making replication and safety comparison difficult. Second, clinics may rely on manufacturer presets that were not validated across diverse skin tones or real-world anatomical sites. Third, documentation of skin tone is inconsistent: Fitzpatrick type measures tanning/burning tendency rather than optical absorption, while self-reported descriptors can be imprecise. Fourth, minor thermal injuries and pigmentary changes may be underreported, limiting feedback loops for improvement.
(5) Equity/safety checks
Adopt “dose discipline.” For every session, document wavelength(s), irradiance, fluence, pulse parameters, exposure time, spot size, anatomical site, and cooling method. Treat darker skin as potentially higher-risk for unintended heating when melanin is a relevant absorber at the chosen wavelength. Use conservative ramping (lower starting settings, longer intervals, enhanced cooling) and close monitoring during early sessions. Implement clear stop rules: unexpected heat/pain, excessive erythema, or delayed blistering triggers immediate protocol revision and incident reporting. For UV phototherapy, use MED-informed or carefully phototype-informed dosing and avoid assuming darker phototypes are ‘automatically safer’ without testing.
(6) Decision questions
• Is this protocol validated for the range of skin tones and anatomical sites you treat?
• Are parameter definitions complete and reproducible (irradiance at tissue, spot size, duty cycle, cooling)?
• Do you have a standardized way to document skin tone/phototype to enable audit and safer personalization?
• Are adverse events captured and reviewed stratified by skin tone/phototype to detect disparity early?
(7) Practical next steps
1) Update consent and patient education to explain differential heating/pigmentary risks and mitigation steps.
2) Implement a standardized treatment log with full parameter set and traceable protocol adjustments.
3) Introduce a first-session safety ramp for higher-risk phototypes: conservative start, monitor, titrate.
4) Run quarterly audits: adverse events per 100 sessions stratified by skin tone/phototype and device model.
5) Align procurement: require vendor documentation of tested conditions and safety labeling consistent with FDA PBM guidance.
(8) References
https://doi.org/10.1111/phpp.70042
https://doi.org/10.4103/ijdvl.IJDVL_88_17
https://doi.org/10.1002/der2.57
https://doi.org/10.1016/j.ad.2019.12.003
https://doi.org/10.21037/atm.2016.05.34
https://www.fda.gov/regulatory-information/search-fda-guidance-documents/photobiomodulation-pbm-devices-premarket-notification-510k-submissions