Fractional lasers are the in-clinic devices that deliver laser energy in a grid of microscopic columns instead of treating the whole surface at once, leaving untouched skin in between so the area heals faster. They have been pointed at the scalp for pattern hair loss for several years now, with results that jump around from one study to the next, so a group at Nanjing University of Chinese Medicine set out to pool all of it. They searched five databases, including the main Chinese-language medical database, from each one's beginning through November 2025, and came out with fifteen studies covering 1,097 adults with androgenetic alopecia, which is the clinical name for pattern hair loss. Hair density measured on dermoscopy was the outcome they pooled. Across seventeen datasets drawn from those fifteen studies, the laser groups gained more hair density than the control groups, with a mean difference of 13.88 (95% confidence interval 6.87 to 20.90). Ablative lasers, the kind that vaporize a little tissue, and non-ablative lasers, the kind that leave the surface intact, came out statistically indistinguishable from each other (p = 0.7792), and so did the three non-ablative wavelengths studied (p = 0.7014). The comparison with the most studies behind it was the add-on question. Across eleven datasets, a fractional laser layered on top of another treatment such as minoxidil beat that other treatment used alone, with a mean difference of 9.74 (95% CI 4.81 to 14.67, p = 0.001). Going the other direction, adding further treatments on top of a laser did not clearly beat the laser by itself, at a mean difference of 23.34 with a range running from -12.82 to 59.50, which includes no effect at all. Side effects reported across the studies were redness, pain and itching, described as mild to moderate and resolving on their own within one to two weeks, with no serious adverse events.

The caveat the authors put on their own headline number is the thing worth carrying out of this paper. Heterogeneity for the overall pooled result was 99.3 percent, which is about as high as that statistic goes, and it means the fifteen studies disagreed with each other almost completely about how large the effect was. A pooled average sitting on top of that much disagreement is a rough estimate of a range, not a figure to quote to anybody as what a laser will do for them. The reason for the disagreement shows up in the paper's own table of study details. Wavelengths ran from 1550 nanometres up to the 10,600 of a carbon dioxide laser, energy settings varied widely, the number of sessions ran from three to twelve, and the gap between sessions ran from one week to one month. Fractional laser is a category of treatment rather than one protocol, and the authors state plainly that the optimal parameters have not been established. One slice did hold together. In the non-ablative subgroup, five datasets gave a mean difference of 13.14 (95% CI 10.53 to 15.75) with zero heterogeneity between them. On quality, the authors rated thirteen of the fifteen studies at low risk of bias and two at high risk on how patients were randomized, and called the overall quality moderate. Not everything included was a randomized controlled trial, with a retrospective cohort study and several split-scalp and unblinded designs in the mix. Egger's test for publication bias came in at p = 0.0553 alongside a visibly asymmetric funnel plot, and the authors report that as possible mild publication bias rather than waving it off. Most participants were men, and several of the included studies enrolled men only, so the female side of this question is thin here. A sensitivity analysis that dropped each study in turn left the overall direction of the result intact. One more thing worth keeping straight: every device in this review was an in-clinic fractional laser, listed by wavelength and energy setting in the paper's table, so none of this speaks to the at-home light caps and combs sold for hair growth, which were not what these studies tested. The authors close by calling for large, high-quality randomized trials with long-term follow-up to pin down the right settings and to define where fractional lasers belong in treatment.

Here's the study: Chen C, Wang S, Bi D, Wei AC, Guo S. Efficacy and safety of fractional laser therapy for androgenetic alopecia: a systematic review and meta-analysis. Journal of Cosmetic Dermatology, 2026;25(5):e70909. doi:10.1111/jocd.70909. Indexed on PubMed (PMID 42121331). Read the full text here.

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