Obagi C25 Serum NEO

Some tingling is normal with 25% ascorbic acid, especially when you first start using it. The high concentration means it's more active than lower percentage vitamin C serums, so mild warmth or slight stinging for a few minutes is expected. If it burns intensely or causes redness, your skin may not be ready for this strength yet. Start with a lower concentration like 10% or 15% and work up.

Most likely, yes. This is the highest concentration vitamin C serum in the Obagi line, formulated for experienced users with resilient skin. If you have sensitive skin or haven't used vitamin C before, start with Obagi C10 or C15 instead. You can always increase concentration later once your skin builds tolerance.

The concentration and formulation quality. At 25% pure ascorbic acid, this is pharmaceutical grade vitamin C at a strength most drugstore brands don't offer. It also includes vitamin E to enhance stability and efficacy. The higher price reflects both the active percentage and Rohto's prestige formulation standards under the Obagi brand.