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Pooled randomised trials show real improvements in skin hydration and elasticity versus placebo, but the effect is moderate, the measures are instrument readings, and the evidence base is shaky.
Pooled diagnostic accuracy is high in specialist settings, but performance falls on Fitzpatrick IV–VI skin and on smartphone images, and most studies never report skin tone at all.
Young men are starting hair-loss drugs early and stacking them with dermarolling and oral minoxidil. Two drugs have decades of evidence; the trend's framing runs ahead of it.
Two ingredients carry most of the real evidence. The rest of the multi-step routine adds cost and, when actives are layered too hard, a damaged skin barrier.
Cochrane pooled 106 randomised trials in 13,631 people; a phenotype-led update reached 152 studies. The best evidence is feature-by-feature — brimonidine for redness, ivermectin and azelaic acid for pustules.
A parental history of acne carries a pooled odds ratio of 2.91. Dairy carries 1.25, from observational studies with demonstrated publication bias — and diet appears nowhere in the treatment guideline.