Vitamin C

What it is

Vitamin C in skincare appears in several forms — L-ascorbic acid (the most-studied but least stable form), and a range of derivatives (like ascorbyl glucoside or tetrahexyldecyl ascorbate) formulated for better stability or gentler tolerability. Because ascorbic acid degrades with exposure to light, air and heat, packaging (opaque, airless, dark glass) and freshness matter as much as the ingredient itself.

What it does

Vitamin C is an antioxidant, meaning it helps neutralize environmental stressors on skin. It's widely used in morning routines alongside SPF.

Who it’s for

Widely used across skin types as a daytime antioxidant step, particularly by people interested in supporting an even, bright-looking complexion.

Possible benefits

• An antioxidant, generally used to help support skin against everyday environmental exposure
• Popular in routines aimed at a brighter, more even-looking complexion
• Often formulated alongside SPF as a complementary morning pairing

Irritation & compatibility considerations

L-ascorbic acid in particular can sting or irritate some skin types, especially at higher concentrations or on compromised skin. Gentler derivative forms are typically better tolerated. Vitamin C is acidic and some people choose not to layer it directly with retinoids or strong acids in the same routine slot, more for stability and comfort than any established safety concern.

How it fits into a routine

Most commonly used in the morning, after cleansing and before moisturizer and SPF, in part because of its antioxidant role alongside daytime sun exposure. A patch test is reasonable before introducing a new formulation, especially at higher percentages.