Kiehl's Dermatologist Solutions Powerful-Strength Line-Reducing Concentrate with 12.5% Vitamin C + Hyaluronic Acid. Clinically demonstrated to decrease appearance of fine lines and wrinkles and improve radiance and texture. A scientific achievement by Kiehl's chemists, this advanced powerful-strength line-reducing concentrate is powered with 10.5% pure Vitamin C, 2% Vitamin Cg & Hyaluronic Acid. The concentrate warms as it activates the skin. Immediately, skin feels smoother and more radiant, and fine lines and wrinkles are reduced over time. Dermatologist-Tested for Safety. EXPIRED.