Thulium Fractional Laser
The 1927nm thulium fractional laser (FTL) occupies a genuinely distinctive position among fractional laser systems because of a single wavelength property: its intermediate water absorption coefficient sits between the non-ablative 1550nm erbium-doped laser (primarily coagulative, stratum corneum left intact) and the ablative 10,600nm CO₂ laser (frank tissue vaporisation). This intermediate absorption coefficient is what allows a single device to span the non-ablative to ablative spectrum by adjusting pulse energy alone – a range that no other fractional infrared laser provides from one system. A 2025 Copenhagen LC-OCT imaging study confirmed this experimentally in real time, mapping the precise MTZ morphology at each energy setting and demonstrating that even low 3mJ pulses create microchannels in the stratum corneum that ablative-style fractional lasers at equivalent low settings do not. The treatment stimulates collagen and elastin synthesis through the wound healing cascade, restores endogenous IGF-1 – the fibroblast growth factor depleted in photoaged and post-menopausal skin – and in clinical fast responders, activates lipid metabolism gene networks that synthesise barrier-restoring ceramides. It has the most consistently safe evidence base for FST IV–VI treatment of melasma and photoaging of any resurfacing modality in the portfolio.
The 1927nm thulium fractional laser delivers laser energy in a fractional pattern – treating discrete columns of tissue (microscopic treatment zones, MTZs) whilst leaving surrounding untreated skin bridges intact. These bridges serve as the reservoir for rapid re-epithelialisation, which is why fractional lasers produce meaningfully less downtime than fully ablative treatment of the same surface area. What distinguishes the 1927nm wavelength from other fractional laser systems is that its water absorption coefficient positions it at the precise intersection of the non-ablative and ablative ranges – making it the only fractional infrared system capable of spanning that spectrum from a single device through pulse energy adjustment. [8]
The Intermediate Water Absorption Mechanism
Water is the primary chromophore at 1927nm – the target tissue component that absorbs the laser energy and converts it to thermal injury. The 1927nm absorption coefficient (~30 cm⁻¹) sits between the 1550nm erbium-doped glass laser (~10 cm⁻¹, predominantly coagulative at all energies) and the CO₂ laser at 10,600nm (~800 cm⁻¹, ablative at all clinical energies). This intermediate coefficient produces a different tissue interaction profile at every energy setting. [8]
At low pulse energies (3mJ), the FTL creates narrow defects beginning at the dermoepidermal junction that extend through the viable epidermis – disrupting the stratum corneum whilst leaving the overlying surface largely intact on the C5 tip, or creating defects that reach the viable epidermis on the C1 tip. At high pulse energies (15–20mJ), the thermal effects expand laterally and vertically, producing wider MTZs and frank ablation into the superficial dermis. The 2025 Copenhagen LC-OCT study mapped this precisely:
MTZ Dimensions by Tip and Energy Setting
| Setting | C1 Tip (200μm spot) | C5 Tip (350μm spot) |
|---|---|---|
| 3mJ – MTZ width | 213μm | 230μm |
| 3mJ – ablation depth | 93μm | 75μm |
| 20mJ – MTZ width | 357μm | 433μm |
| 20mJ – ablation depth | 101μm | 115μm |
| Character at 3mJ | Disrupts viable epidermis | Subepidermal cleft; SC largely spared |
| Character at 20mJ | Full epidermal poration | Frank ablation to superficial dermis |
Source: [8]
This data has practical consequences beyond academic interest. The C5 tip at 3mJ produces the most conservative intervention – subepidermal effects with the stratum corneum largely preserved – whilst still creating the SC microchannels sufficient for laser-assisted drug delivery (LADD). The C1 tip at equivalent energy is immediately more disruptive. Understanding this distinction allows energy and tip selection to be matched precisely to the clinical objective rather than adjusted by feel.
One important characteristic of the FTL that the LC-OCT study confirmed is that it does not follow the linear depth-to-energy profile typical of other fractional infrared lasers. The 1540nm erbium laser, for example, shows a depth increase of 100–150μm per 10mJ energy increase in a predictable linear pattern. The FTL does not show this pattern: depth increases are non-linear, with diminishing returns at higher energies as lateral MTZ expansion becomes the dominant effect rather than deeper penetration. [8] Energy settings therefore primarily control breadth of thermal effect and degree of epidermal disruption, not a straightforward increase in treatment depth – a clinically meaningful distinction when calibrating for darker skin types where SC disruption management is a primary safety concern.
Wound Healing Cascade, HSP47, and IGF-1
The fractional thermal injuries in treated MTZs initiate the standard three-phase wound healing cascade – inflammation, proliferation, and remodelling – releasing TGF-β, PDGF, and VEGF and recruiting fibroblasts to synthesise Type I and III collagen and elastin. The thermal component, as with MNRF, upregulates HSP47 (the collagen-specific chaperone that stabilises procollagen triple helices during synthesis) and HSP70, extending collagen synthesis activity beyond the acute wound phase. Neocollagenesis continues for three to six months post-treatment as HSP47 expression gradually builds, producing progressive skin tightening and texture improvement that outlasts the initial post-treatment erythema period by a considerable margin.
An additional mechanism that the FTL shares with RF microneedling is that it connects to a broader framework: endogenous IGF-1 restoration. Insulin-like growth factor 1, produced by fibroblasts and essential for collagen synthesis signalling, declines progressively in photoaged and post-menopausal skin – and this IGF-1 deficit is a significant reason why chronically photodamaged skin responds less productively to collagen synthesis stimulation than the mechanism alone would predict. Controlled thermal injury to the dermal fibroblast environment via FTL – as with RF microneedling – appears to restore IGF-1 expression in treated tissue, re-establishing the autocrine growth factor environment that makes further collagen synthesis signals effective. This is the mechanistic rationale for pairing FTL with iPRF post-treatment: the laser restores endogenous IGF-1 whilst iPRF provides exogenous growth factor delivery through the same IGF-1 receptor pathway, producing an additive rather than redundant effect.
Drug Delivery: The LADD Advantage
The 1927nm FTL has a structurally significant drug delivery function that is more versatile than standard microneedling’s microchannel delivery, because the degree of SC disruption is calibrated by pulse energy – from minimal SC microchannels at 3mJ (sufficient for enhanced topical penetration) to frank SC ablation with full epidermal poration at 20mJ (direct dermal access). The 2025 Copenhagen LC-OCT study noted that the FTL creates SC microchannels even at low 3mJ settings – something that classical non-ablative fractional lasers, which leave the SC intact, do not produce – and that this SC disruption underpins the FTL’s established superiority for laser-assisted drug delivery (LADD) compared to 1550nm or 1540nm alternatives. [8]
In clinical practice this has been confirmed for photodynamic therapy applications and for topical tranexamic acid and vitamin C delivery in melasma treatment – the combination of SC disruption and an immediate inflammatory-resolution window produces drug penetration profiles that topical-only application at any concentration cannot match. The drug delivery window follows MTZ formation and is optimised by immediate post-treatment application; it is not extended by waiting.
Barrier Restoration: The Ceramide and Lipid Metabolism Finding
Perhaps the most clinically underappreciated dimension of thulium FTL treatment is its effect on epidermal lipid synthesis – a finding that distinguishes the FTL from purely structural collagen-stimulating devices and connects it directly to the Skin Barrier entity’s ceramide-TEWL framework.
A 2022 gene expression study using the 1927nm FTL identified two distinct responder profiles in photoaged patients – fast responders (visible improvement within days of treatment) and slow responders – and performed comprehensive transcriptomic analysis to characterise what separated them at the molecular level. [2] The separation was not primarily in structural collagen pathways. Fast responders showed significantly greater activation of lipid metabolism gene networks: PPAR signalling, peroxisome, glycerolipid metabolism, and fatty acid metabolism pathways were all more strongly activated in fast responders at days 1 and 14 post-treatment. Within these pathways, two specific mechanisms have direct barrier consequences:
- AGPAT1 and AGPAT3 catalyse the formation of glycerolipids that restore skin permeability barrier function following disruption – their upregulation in fast responders suggests active barrier reassembly at the lipid level.
- FA2H promotes the synthesis of 2-hydroxylated ceramides – the ceramide species specifically strengthening epidermal barrier function. [2]
Additionally, fast responders showed greater reversal of photoaging-associated lipid derangements: genes including FADS1, FADS2, ELOVL3, and FAR2 – known to be downregulated in photoaged skin – were more robustly upregulated in fast responders following treatment. [2]
The clinical implication is meaningful in both directions. Patients who respond rapidly and visibly to FTL treatment are, molecularly, those whose photoaged skin most efficiently re-activates the lipid synthesis machinery that barrier function depends on. The treatment is not simply stimulating collagen and improving surface appearance; in fast responders it is actively reversing photoaging-associated lipid metabolism derangements at the gene expression level. Conversely, slow responders’ relative absence of this lipid pathway activation suggests their barrier restoration requires more support – which is the mechanistic case for combining FTL treatment with PDRN (which upregulates SPTLC3-driven ceramide synthesis independently) in clients who historically plateau on single-modality protocols.
Re-epithelialisation and MEND Formation
The LC-OCT imaging study provided the first real-time visualisation of the post-FTL healing sequence at the tissue level. At 24 hours, epidermal disruptions had re-epithelialised with inwardly migrating keratinocytes creating an epidermal “bridge” beneath newly formed microscopic epidermal necrotic debris (MENDs). By day 7, MENDs displayed progressive upward extrusion towards the skin surface. [8] The MEND extrusion process is the biological explanation for the “bronzing” that clients describe in the days following FTL treatment – the microscopic columns of thermally altered cells being exfoliated through the otherwise intact stratum corneum. Understanding that this is a predictable, mechanistically understood healing sequence (not a sign of excessive treatment) is both clinically useful and consultation-relevant.
Evidence Base
The evidence base for the 1927nm FTL is moderate-to-strong and maturing rapidly – several of the most meaningful studies are from 2023–2026.
Photoaging and skin texture: A 2023 prospective study of 45 patients with Asian skin (FST II–IV) found statistically significant improvement in wrinkles, pores, melanin index, and elasticity after three monthly treatments. [5] A December 2025 systematic review of thulium 1927nm laser across dermatological conditions confirmed safe and effective treatment across all Fitzpatrick skin types, identifying fluence, density, and number of passes as the primary variables governing both efficacy and the risk of post-inflammatory hyperpigmentation in darker skin types – with conservative parameter selection the consistent recommendation for FST IV–VI. [pubmed.ncbi.nlm.nih.gov(https://pubmed.ncbi.nlm.nih.gov/41379329/)
Melasma (FST III–IV): The most consistently strong evidence area. A split-face study in Dermatologic Surgery (2013) found 70% reduction in pigmentation in FST III–IV after four treatments, with histological confirmation of collagen regeneration and melanin decrease. This remains one of the best-evidenced indications for any laser system in darker skin types. [4]
Acne scarring: A 2023 prospective split-face RCT (Lasers in Surgery and Medicine, n=30) evaluating 1927nm TFL monotherapy against TFL combined with 30% supramolecular salicylic acid confirmed that TFL monotherapy alone produced statistically significant improvement in ECCA scar scores across four sessions – with the combination arm showing superior improvement in scar grade, melanin index, erythema index, and TEWL, and no adverse events in either group. [3] The underlying mechanism was further characterised in a 2024 Seoul case series (Clinical, Cosmetic and Investigational Dermatology, n=9, FST III–IV) with 32-week follow-up, which confirmed that the FTL’s ~400μm coagulative depth reaches the follicular infundibulum and sebaceous glands – simultaneously destroying Cutibacterium acnes, inducing follicular remodelling, and triggering dermal collagenesis and elastinogenesis in surrounding non-lesional tissue, providing concurrent scar and overall skin quality benefit in the same session. [1]
Non-facial photodamage: A 2026 Copenhagen study compared thulium FTL monotherapy vs. FTL combined with photodynamic therapy for décolleté photodamage, confirming the 1927nm FTL as an effective, tolerable, and safe field-directed treatment for non-facial photodamage as a standalone modality. This is one of the few studies specifically addressing décolleté treatment with high-quality design. researchprofiles.ku
Hair loss: A prospective study of 1927nm FTL monotherapy for hair loss confirmed significant increase in hair count, suggesting the treatment’s follicular growth factor stimulation (likely via VEGF upregulation) produces clinically measurable effects independently of PDT or PRP combination. [6]
LC-OCT tissue interaction: The 2025 Copenhagen in vivo imaging study provides the first precise, real-time characterisation of FTL MTZ morphology across the full pulse energy range – a quality and resolution of tissue interaction data that no previous histological study had achieved, and which substantially strengthens the mechanistic evidence base for energy and tip selection decisions. [8]
Clinical Application
The thulium FTL occupies the upper tier of the portfolio’s skin quality and photoaging treatments – above standard microneedling and RF microneedling in terms of surface treatment versatility, and uniquely positioned as the primary resurfacing tool for melasma and dyspigmentation across all skin types including FST IV–VI. Its correct positioning within a client’s treatment pathway, however, depends entirely on barrier status – a consideration that deserves more clinical specificity than “barrier stabilisation helps guide timing.”
The treatment works through controlled disruption and accelerated regeneration. Each pulse creates a thermal wound and relies on the skin’s intrinsic repair capacity to resolve it with improved structure. This means that in skin with an already compromised barrier – chronic dehydration, active inflammatory conditions, significantly impaired TEWL – the regenerative response is attenuated, the healing sequence is slower, and the risk of post-inflammatory hyperpigmentation is higher. Barrier preparation before FTL is not a conservative precaution; it is mechanistically necessary for optimal outcomes.
In practical terms: a client presenting with photoaging, dyspigmentation, and a compromised barrier should have barrier function addressed first – whether through polynucleotides, topical ceramide restoration, or a course of skin boosters – before the FTL course begins. The fast responder ceramide data reinforces this: the clients who respond most rapidly and visibly are those with the most intact and responsive lipid synthesis machinery. Building that foundation first narrows the gap between fast and slow responders.
Who benefits most
Clients with melasma, dyspigmentation, or sun damage across any FST including IV–VI. This is the indication where the FTL is most demonstrably superior to alternatives: it treats melanin irregularities through direct thermal disruption and normalisation of melanogenesis in the treated columns, and does so with a safety profile for darker skin types that neither the CO₂ laser nor the majority of ablative fractional alternatives provide. Conservative energy settings, mandatory patch testing, and pre-treatment hydroquinone priming (two to four weeks) are the tools that make this safe – not avoidance of the treatment.
Clients with acne scarring, particularly in darker skin types where laser options are usually restricted. The FTL’s FST safety profile and moderate downtime (three to seven days) make it the most accessible fractional resurfacing option for FST IV–VI clients with atrophic scarring, where ablative laser alternatives carry unacceptable PIH risk.
Clients seeking moderate-downtime resurfacing positioned between microneedling’s negligible downtime and CO₂ laser’s extended recovery: three to seven days of erythema and MEND extrusion (“bronzing”), return to normal activities within 24–48 hours, minimal bleeding or wound management required.
Post-menopausal clients with significant photoaging. The FTL’s dual IGF-1 restoration and ceramide lipid synthesis activation adds dimensions that standard needling-based treatments cannot provide in this population. The combination of structural collagen stimulation, endogenous IGF-1 restoration, and barrier lipid pathway reactivation addresses structural collagen stimulation, barrier lipid pathway reactivation, and heat shock protein-driven neocollagenesis – three dimensions of photoaged skin decline that no single needling-based treatment addresses concurrently.
Non-facial applications – décolleté, neck, hands. The 2026 Copenhagen study confirms efficacy on the décolleté specifically. Non- facial skin has thinner dermis, fewer appendages for re-epithelialisation, and slower healing than facial skin – which means conservative energy settings and wider intervals than facial protocols are necessary, but the treatment is well-supported for these areas in ways that more aggressive resurfacing modalities are not.
Setting expectations honestly
Visible improvement in texture and luminosity is often noticeable within the first two weeks as the MEND extrusion cycle completes – the skin feels noticeably smoother as the thermally altered columns are cleared. The structural collagen changes accumulate over three to six months and continue beyond the final session in the course as heat shock protein-mediated neocollagenesis continues. For melasma, improvement is often visible early (2–4 weeks) but requires consistent sun protection and maintenance protocols to prevent recurrence – the laser addresses the existing pigmentation, but does not permanently alter the melanocyte responsiveness that produced it.
The bronzing/MEND extrusion phase (days two to seven) should be communicated explicitly as the normal healing sequence, not as an adverse event. Clients who are not told to expect it will frequently be alarmed by it, or worse, attempt to exfoliate or peel it, which disrupts the MEND extrusion process and prolongs healing. The advice is simple: do not assist the process – let the skin shed on its own timeline.
Where combinations are most productive
FTL + iPRF is the most complete combination for post-menopausal or significantly photodamaged clients. The FTL’s thermal wound response initiates the same growth factor signalling cascade – including TGF-β and VEGF upregulation – that primes fibroblast receptivity to exogenous growth factor delivery; iPRF delivers exogenous growth factor payload ( PDGF, TGF-β, IGF-1, VEGF) through the same receptor pathways that the restored IGF-1 environment has just primed to receive. Apply iPRF during or immediately after the laser treatment session whilst the microchannels and inflammatory signalling window are active.
FTL + polynucleotides for clients with barrier compromise or persistent photodamage. The PN course addresses the MMP-inflammatory burden and upregulates SPTLC3-driven ceramide synthesis independently of the laser’s lipid metabolism pathway activation – the two routes to ceramide restoration are complementary rather than redundant. Sequencing: PN before FTL to restore the barrier environment; or PN after FTL as a recovery-phase support to accelerate barrier re-establishment.
FTL + tranexamic acid (LADD) for melasma: topical tranexamic acid applied immediately after FTL treatment under occlusion – within the SC disruption window – extends the durability of the FTL result. A 2020 split-face double-blind RCT (n=46, FST III–V) confirmed FTL alone produces significant melanin index and mMASI improvement at three months; the TXA-assisted side maintained this improvement through six months whilst the FTL-only side partially regressed – making FTL + TXA the more complete protocol where long-term melasma management is the goal. [7]
FTL + RF microneedling (sequenced, not simultaneous). The two treatments are genuinely complementary: FTL addresses surface photoaging, dyspigmentation, and barrier lipid pathways; MNRF addresses structural laxity, senescent fibroblast clearance, and elastic fibre restoration. They share the IGF-1 mechanism but operate through distinct wound and thermal pathways in different tissue zones. Sequencing depends on the primary concern – if the starting point is surface quality, FTL first; if structural laxity is the dominant concern, MNRF first – with a four to six week interval between modalities to allow each wound healing cycle to resolve before initiating the next.
The Protocol Reference
| Treatment Goal | Recommended Approach | Combination Logic |
|---|---|---|
| Photoaging / skin texture | 3–5 sessions, 4–6 week intervals | + iPRF same session; PDRN pre-course |
| Melasma (FST III–IV) | 4 sessions, 4–6 weeks; patch test + priming | + tranexamic acid LADD; + SPF50 mandatory |
| Acne scarring (FST IV–VI) | 3–5 sessions, 4–6 week intervals | + PDRN for inflammation; conservative settings |
| Décolleté / non-facial | 3–4 sessions; conservative energy; wider intervals | + PDRN or PN for barrier support post-treatment |
| Hair loss | 3–4 scalp sessions, 4–6 week intervals | + iPRF for combined VEGF/growth factor delivery |
| Drug delivery (LADD) | Session-by-session; apply actives within minutes of treatment | Tranexamic acid, vitamin C, PDRN, HA |
| Pre-MNRF preparation | 1–2 FTL sessions to address surface quality first | Establish skin quality before structural escalation |
References
Chun SI (2024). A Novel Treatment of Acne Vulgaris Using a 1927 nm Fractional Thulium Laser: A Case Series. Clin Cosmet Investig Dermatol, 17, 1931-1942 . doi.org/10.2147/ccid.s468326
Garza LA, Sheu M, Kim N, et al. (2023). Association of Early Clinical Response to Laser Rejuvenation of Photoaged Skin with Increased Lipid Metabolism and Restoration of Skin Barrier Function. J Invest Dermatol, 143(3), 374-385.e7 . doi.org/10.1016/j.jid.2022.07.024
Huang SL, Ye D, Xue H, et al. (2023). 1927nm fractional thulium fiber laser combined with 30% salicylic acid for the treatment of acne and acne scars: A prospective, randomized, and split-face study. Lasers Surg Med, 55(9), 829-837 . doi.org/10.1002/lsm.23708
Lee HM, Haw S, Kim JK, et al. (2013). Split-face study using a 1,927-nm thulium fiber fractional laser to treat photoaging and melasma in Asian skin. Dermatol Surg, 39(6), 879-88 . doi.org/10.1111/dsu.12176
Li X, Qin S, Shi S, et al. (2023). Prospective study of efficacy and safety of non-ablative 1927 nm fractional thulium fiber laser in Asian skin photoaging. Front Surg, 10, 1076848 . doi.org/10.3389/fsurg.2023.1076848
Oliveira Modena DA, Melo Yamamoto AP, Ferreira da Silva TB, et al. (2025). Thulium laser (1927 nm) for dermatological conditions: a systematic review. Lasers Med Sci, 40(1), 518 . doi.org/10.1007/s10103-025-04781-5
Wanitphakdeedecha R, Sy-Alvarado F, Patthamalai P, et al. (2020). The efficacy in treatment of facial melasma with thulium 1927-nm fractional laser-assisted topical tranexamic acid delivery: a split-face, double-blind, randomized controlled pilot study. Lasers Med Sci, 35(9), 2015-2021 . doi.org/10.1007/s10103-020-03045-8
Wenande E, Jacobsen K, Grove GL, et al. (2025). Imaging 1927 nm Fractional Thulium Laser-Tissue Interactions: A Spectrum of Nonablative to Ablative Effects. J Cosmet Dermatol, 24(7), e70304 . doi.org/10.1111/jocd.70304
Also Known As
- FTL
- thulium FTL
Therapeutic Relationships
Indications & References
- this Corneocyte
- this Dermis Evidence: Thulium fractional MTZ mechanism reaches the papillary dermis… producing collagen deposition and DEJ remodelling at the boundary zone
- this Epidermis Evidence: Entity text explicitly states thulium fractional laser acts at the epidermal and papillary dermal level as a professional treatment for skin quality.
- this Keratinocyte Evidence: MTZ injury drives re-epithelialisation from hair follicle keratinocyte stem cells that retain higher COL17A1 expression than the photodamaged surface population
- this Skin Evidence: Thulium laser acts at epidermal and papillary dermal levels; improves keratinocyte differentiation.
- this Stratum corneum Evidence: Thulium laser listed as a differentiation booster addressing corneocyte quality in the bricks-and-mortar table: “Differentiation boosters (Thulium, Retinoids)” (full_description).
- this May treat Perimenopausal skin changes Evidence: Fractional laser resurfacing addresses epidermal thinning, photodamage, and texture changes characteristic of perimenopausal skin. Entity text.
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1927nm thulium laser providing gentle resurfacing with less downtime than traditional ablative lasers. Research shows fast responders had greater activation of lipid metabolism genes for fatty acids and ceramides, potentially strengthening barrier long-term. For use after barrier stabilisation.