A comprehensive evidence-based dermatology review evaluating Korean skincare (K-beauty) ingredients, multi-step routines, sunscreen formulation science, and trending practices against peer-reviewed clinical trial data. This review grades 18 popular K-beauty ingredients from Strong to Weak evidence, analyzing niacinamide, Centella asiatica, snail mucin, galactomyces ferment filtrate, propolis, rice ferment, mugwort, and others. It examines the science behind multi-step layering routines, pH-adjusted cleansing, sheet masks, glass skin, slugging, ceramide formulations, microbiome claims, and Korean sunscreen superiority. Clinical evidence is drawn from 34 peer-reviewed sources. Key findings: Niacinamide and broad-spectrum sunscreen have Strong clinical evidence. Centella asiatica, tranexamic acid, and ceramides have Moderate evidence. Most trending K-beauty hero ingredients lack adequate controlled human trial data to support their marketing claims. Originally published: DermaVue Clinical Reviews, Vol 10, No 1, February 2026Full article: https://dermavue.com/research/k-beauty-science-vs-hype-dermatology-review/