Clinical Study on Epidermal Cell Renewal Efficacy of 5 Products

This is a single-center, double-blind, randomized, and controlled study. The sponsor keeps the allocation of products to the six test sites confidential. Neither the evaluating physicians nor the participants know which product is applied to which site.

The investigator will recruit 33 Chinese female participants and aim to complete the study with at least 30 of them. Each participant will be followed for 23 consecutive days.

• **Day 0**: After signing informed consent and passing screening, a staff member performs a dansyl chloride patch test. The reagent is placed in a Finn chamber, applied to the inner forearm, and sealed with waterproof tape.
• **Day 1 (≥20 h later)**: Participants return to the site. The patches are removed, photographs are taken, and the designated test products are applied to the marked areas.
• **Days 2-21**: Participants visit daily for product application by staff. After each use they report any adverse reactions, specifying symptoms, severity, location, and duration. Starting on Day 1, a dermatologist performs daily clinical scoring and photography of the test areas.

Throughout the study, participants must avoid sunscreen and any other skin-care products on the inner forearms. From Day 0 to Day 1 they may not bathe or wet the forearms; during the remaining application period they may shower but must not rub or scrub the inner forearms, and must still refrain from any other topical products.