Sh-Polypeptide-9

Sh-Polypeptide-9 is a synthetic/human-identical signaling peptide used at very low levels in leave-on products (typically well under 0.1–1%), and peptides as a class show low irritation in standard patch-testing when properly formulated. The main risk is not inherent causticity but rare hypersensitivity or irritation from the overall formula (preservatives/solubilizers), so for patient-safety in highly reactive or eczema-prone skin I rate it as very gentle rather than exceptionally gentle. Safety Notes: Sh-Polypeptide-9 is a recombinant/cosmetic bio-peptide typically supplied as a dilute solution and used at very low levels in consumer leave-on serums and creams; at the low end it appears as a label-claim peptide at ~0.1–10 ppm active. Higher-strength OTC “peptide booster”/ampoule-type products and multi-peptide serums can reach ~0.01–0.05% active when the supplier solution is dosed aggressively, with higher levels uncommon due to cost, stability, and diminishing returns; it is rarely used meaningfully in rinse-off formats where deposition is limited.