1. Retinoid Routine
Winter, with its lower UV index and reduced sebum and perspiration production, provides an ideal environment for introducing retinoid care—especially treatments that require a gradual adaptation period. 2. High-Potency Vitamin C
Vitamin C is inherently sensitive to heat and light and therefore prone to oxidation. In winter, however, lower temperatures and reduced UV exposure enhance both its stability and efficacy. 3. Melanin-Targeted Care
As melanin production and oxidation are relatively suppressed during this season, winter allows for faster and more effective results in pigmentation-focused treatments. 4. Vegan Peptide & Growth Factor Ampoules The drier the skin, the more readily active ingredients are absorbed. Winter thus becomes an optimal season for maximizing the benefits of consistent, well-structured skincare routines. 5. Peeling & Turnover Routine
With a lower risk of inflammation caused by excess sebum and the presence of winter’s characteristic thickened keratin layer, this season is particularly well suited for effective exfoliation and skin turnover care (Hyangjang, p. 688). | 
