Obagi Vitamin C Serum 20%

I've been using the Obagi Professional-C 15% Vitamin C Serum for several months and have noticed brighter, smoother skin and fewer fine lines. One bottle lasts me around 6 months with daily use, so it’s definitely worth the investment. The serum starts out clear and gradually turns yellow over time, which is normal for vitamin C. To help limit oxidation and prolong its effectiveness, I keep it stored in a cool, dark place. The one pictured is 6 months old and at the end of its use. It absorbs quickly and layers great with my other skincare. A must-have in my routine!