Osmosis is a small and focused line on our shelf, built around retinaldehyde and antioxidants rather than conventional retinol. It suits clients who want what a retinoid does for the look of texture and fine lines, but have found standard formulas too irritating to stay on past the second week.

Correct MD is the entry point. Renew MD Advanced Retinal Serum is the stronger version once skin is comfortable with the first, and Calm Retinal Serum is the one we suggest for redness-prone skin. Rescue MD Epidermal Repair Serum is the outlier here, not a retinal at all, and the one we hand clients after a stronger facial to keep skin comfortable. Introduce any retinal two nights a week, with SPF the next morning.