Acne pathogenesis: the central role of the sebaceous gland

Acne vulgaris — a chronic inflammatory disorder of the pilosebaceous unit — remains one of the most common conditions seen by dermatologists and skincare specialists worldwide. Epidemiological data suggest that up to 85% of people between the ages of 12 and 24 are affected, and the condition frequently persists into adulthood. Beyond its visible impact on the skin, acne carries a substantial psychosocial burden: diminished self-esteem, anxiety, and depression are well-documented companions of the disease, particularly during adolescence [1].

At the core of acne pathogenesis lies hypersecretion of sebum by the sebaceous glands. Excess sebum creates an environment that favors colonization by Cutibacterium acnes (C. acnes), promotes comedone formation, and triggers the inflammatory cascade that follows. The sebaceous gland is both the structural and functional origin of this process. Yet most established treatments — systemic antibiotics, topical retinoids, oral isotretinoin — address various steps in the pathogenic chain without directly eliminating the gland itself. Meanwhile, the problem of antimicrobial resistance is growing: rising resistance of C. acnes to antibiotics increasingly limits the long-term use of antimicrobial agents [2].

Light-based acne therapies: what exists and where they fall short

Light and laser treatments for acne have been evolving for decades, and today practitioners have a range of options at their disposal.

Blue light (around 415 nm), green and yellow light, and intense pulsed light (IPL) work primarily through photoinactivation of C. acnes: the bacteria produce porphyrins that, upon light absorption, generate reactive oxygen species. The effect is real but limited — these wavelengths do not meaningfully reach the sebaceous glands located in the deeper layers of the dermis.

Photodynamic therapy (PDT) with aminolevulinic acid (ALA) is the most extensively studied light-based approach for acne. It produces a more pronounced response, in part because the photosensitizer accumulates to some degree in sebaceous glands. However, the method is constrained by significant practical drawbacks: considerable discomfort during treatment, acneiform flares in the weeks following a session, and a risk of post-inflammatory hyperpigmentation (PIH) — particularly in patients with darker skin tones [4].

High-intensity infrared lasers in the 1320–1450 nm range can reduce inflammatory lesion counts. Still, their mechanism relies on non-selective tissue heating through water absorption, with no preferential targeting of sebaceous glands. The result is intense procedural pain, prolonged erythema, and skin irritation — factors that significantly limit their use in everyday clinical practice.

In short, despite decades of development, no existing light-based modality achieves true seboselective action — none structurally disrupts the sebaceous gland or produces a sustained reduction in sebum output.

From the free electron laser to the clinic: the origin of the idea

The concept of seboselective laser targeting is not new. A pivotal moment came with preclinical experiments using a free electron laser tuned to the 1600–1800 nm range, which selectively damaged sebaceous glands without injuring the epidermis [3]. This observation raised a fundamental question: why this particular wavelength range?

The answer lies in the biochemistry of sebum. Skin surface lipids are a complex mixture of triglycerides, wax esters, squalene, and fatty acids. Spectroscopic analysis in the short-wave infrared (SWIR) region revealed that sebum has a pronounced absorption peak near 1726 nm — a narrow band where its absorption coefficient substantially exceeds that of water. This is the "seboselective window": a wavelength at which sebaceous lipids are preferentially heated while water-rich structures — the epidermis and dermis — are largely spared.

1726 nm laser: how it works

The 1726 nm laser applies the principle of selective photothermolysis, with sebum as the target chromophore. The thermal energy delivered to sebaceous lipids is sufficient to cause structural damage and functional suppression of the glands residing in the deep dermis. Integrated contact cooling protects the epidermis and improves patient comfort during the procedure.

Critically, this is not an antibacterial approach, nor does it rely on non-selective tissue heating. The laser acts directly on the glandular structure responsible for excess sebum production — addressing the root cause of acne rather than its downstream consequences.

Study design

A study by Goldberg D. et al., published in the Journal of the American Academy of Dermatology in 2026, presents one-year results from a prospective, multicenter, open-label trial evaluating the efficacy and safety of a 1726 nm sebum-selective laser for acne across a range of skin phototypes [1]. The study was approved by an institutional review board and conducted across multiple clinical centers in the United States.

Eligible participants were 16 to 60 years of age with moderate-to-severe facial acne (IGA — Investigator's Global Assessment — score of 2–4; at least 15 inflammatory lesions) and Fitzpatrick skin types (FST) II–VI. A total of 104 participants were enrolled; each received three treatment sessions at 2–5 week intervals, with follow-up assessments at 12 and 52 weeks after the final session. The cohort was demographically diverse: 39% of participants had FST IV, 29% FST III, and 18% combined FST V and VI. Mean age was 22.2 years (± 5.5); 56.7% of participants were female. Efficacy was assessed by inflammatory lesion counts (ILC) from standardized photographs and by IGA scores; safety was monitored throughout the entire observation period.

Results: an effect that builds over time

By week 12, 79.8% of participants in the per-protocol cohort had achieved a 50% or greater reduction in inflammatory lesion counts, with a mean reduction of 49.4%. The proportion of patients rated as "clear" or "almost clear" on the IGA scale reached 36.0%.

The most striking findings emerged at week 52 — one year after completing the treatment course. In the per-protocol cohort (n=71), 91.5% of patients demonstrated a 50% or greater reduction in inflammatory lesions, with a mean reduction of 70.9%. The share of participants achieving an IGA rating of "clear" or "almost clear" rose to 66.2%.

This progressive improvement over 12 months is consistent with the hypothesis that damaged sebaceous glands undergo gradual elimination, and that sebum secretion declines over a period of months following treatment — a biological process that unfolds well beyond the final laser session.

Safety and adverse events

Adverse events (AEs) were predominantly mild and self-limiting. The most common — erythema (100% of participants) and edema (98.1%) — were expected post-procedural responses that resolved without intervention. Acneiform flares, or purging, occurred in 44.2% of patients in the weeks following treatment, a phenomenon also observed with other sebaceous gland-targeting modalities. Additional AEs included skin dryness (18.3%), itching (1.9%), skin sensitivity (1.9%), and a sensation of oiliness (1.0%).

No blistering, scarring, or pigmentary changes were observed in any participant. No serious AEs were reported. Of particular clinical relevance is the absence of pigmentary complications in patients with darker skin tones (FST IV–VI) — a population historically vulnerable to pigmentation-related side effects from laser and light-based treatments, and one that is frequently excluded from such trials.

Limitations

The authors acknowledge several limitations. The study was open-label and lacked a control group, making it difficult to fully distinguish treatment effects from the natural course of the disease. Participant dropout by week 52 reduced the size of the per-protocol cohort. Additionally, the study focused exclusively on facial acne — the most common site of sebaceous gland involvement — and the findings cannot be automatically extrapolated to other affected areas such as the back or chest. Randomized controlled trials with longer follow-up periods will be needed to definitively establish the role of the 1726 nm laser in acne management.

Clinical outlook

The 1726 nm laser opens a genuinely new therapeutic niche — direct targeting of the sebaceous gland — that no existing light-based or laser modality has previously occupied. The technology may be of particular value for patients in whom conventional options are unavailable or undesirable: those with contraindications or intolerance to isotretinoin, those affected by growing antibiotic resistance, or those at elevated risk of pigmentary complications from other light-based therapies. A relatively short treatment course — three sessions spaced a few weeks apart — combined with an effect that continues to strengthen over the following year makes this an attractive option for both clinical dermatology and aesthetic practice [5].

The safety profile observed in patients with FST IV–VI positions the 1726 nm laser as a potential tool for treating darker skin tones — a group that has historically had limited access to laser-based acne therapies.

Conclusion

The 1726 nm laser represents a new paradigm in acne treatment: selective photothermolysis of the sebaceous glands — the structures at the origin of the disease. One-year data from a prospective multicenter study demonstrate strong efficacy, with more than 91% of patients with moderate-to-severe acne achieving at least a 50% reduction in inflammatory lesions and outcomes continuing to improve over 12 months. A favorable safety profile — including in patients with darker skin phototypes — and the absence of serious adverse events make this technology a promising candidate for broad clinical adoption. The next step is randomized controlled trials to definitively define the place of the 1726 nm laser in the acne treatment algorithm.

References

1. Goldberg D., Ronan S., Bhatia A.et al. Safe and effective acne treatment across skin types with a 1726 nm sebum-selective laser. J Am Acad Dermatol. 2026. DOI: 10.1016/j.jaad.2025.09.077
2. Walsh T.R., Efthimiou J., Dréno B. Systematic review of antibiotic resistance in acne: an increasing topical and oral threat. Lancet Infect Dis 2016; 16(3): e23–e33.
3. Sakamoto F.H., Doukas A.G., Farinelli W.A. et al. Selective photothermolysis to target sebaceous glands: theoretical estimation of parameters and preliminary results using a free electron laser. Lasers Surg Med. 2012; 44(2): 75–183.
4. Hongcharu W., Taylor C.R., Chang Y. et al. Topical ALA-photodynamic therapy for the treatment of acne vulgaris. J Invest Dermatol 2000; 115(2): 183–192.
5. Alexiades M., Kothare A., Goldberg D. et al. Novel 1726 nm laser demonstrates durable therapeutic outcomes and tolerability for moderate-to-severe acne across skin types. J Am Acad Dermatol 2023; 89(4):703–710.