Leave-on scalp serums accounted for a measurable share of new peptide-containing SKUs launched in North America and Southeast Asia during H2 2025. Sequences selected for hydrophilicity at pH 5.0–6.0 dominate, often co-formulated with panthenol or niacinamide. Several raw-material vendors now publish preservative compatibility matrices—a response to failed micro-challenges when peptides entered fragranced systems without prior screening.