Effectiveness and Safety of Recombinant Type <scp>III</scp> Humanized Collagen Solution Injection Combined With Collagen‐ <scp>III</scp> Multi‐Peptide Serum in Improving Signs of Photoaging: A Prospective, Split‐Face Controlled Clinical Trial

BACKGROUND: Skin aging is a multifactorial process involving the progressive deterioration of skin structure and function, marked by collagen degeneration, impairing the structural integrity of the dermis. Intradermal injection of recombinant type III humanized collagen (RhCol-III) solution is a promising anti-aging strategy through direct collagen replenishment, but its synergistic effects when combined with a collagen-III multi-peptide serum remain unexplored. AIMS: This study evaluates the effectiveness and safety of a RhCol-III solution injection combined with a collagen-III multi-peptide serum in improving photoaging. METHODS: A prospective, single-center, randomized, split-face, single-blind trial was conducted. Participants received an intradermal injection of 2 mg/mL RhCol-III solution with application of collagen-III multi-peptide serum on the test side and intradermal injection of RhCol-III solution only on the control side. The 12-week follow-up period assessed effectiveness and safety, with the primary endpoint being the participant-reported skin satisfaction score (FACE-Q satisfaction with skin) at 4 weeks post-treatment. RESULTS: A total of 54 participants were enrolled. The primary endpoint, FACE-Q skin satisfaction score at week 4, significantly improved on both tested and control sides by 40.0% vs. 34.8% from baseline (both p < 0.0001; p < 0.05 between sides). By week 12, the tested side showed significantly better outcomes versus the control side in FACE-Q skin satisfaction scores, GAIS significant improvement rates, improvement rates of fine lines and skin firmness (all p < 0.05). No adverse events related to the RhCol-III solution injection were observed. CONCLUSIONS: The combination of injectable RhCol-III and topical collagen-III multi-peptide serum is effective and safe in ameliorating photoaging of the forehead, periorbital and cheek areas among the Chinese population.