Morning serum is armor. Night serum is construction.
AM is about defense—your vitamin C fights pollution and blue light all day. PM is for repair—retinols and acids work best in the dark, literally. Using the right one at the wrong time is like wearing pajamas to the gym.
Sunday Riley’s C.E.O. 15% Vitamin C Brightening Serum. $85. The claim that it’s stable and doesn’t sting made me try it.
THD Ascorbate
This is the stable, oil-soluble form of vitamin C—it won’t oxidize in the bottle by Tuesday.
15% Concentration
High enough to be effective, low enough that my sensitive skin didn’t stage a revolt.
Squalane Base
Feels like a hydrating oil, not a dry, scratchy serum. A surprise for a vitamin C.
Photo: freestocks / Unsplash
It’s not just vitamin C in a bottle. The formula is built to penetrate and soothe. The hero is THD Ascorbate, but the supporting cast does heavy lifting.
- THD Ascorbate: Oil-soluble vitamin C that actually sinks in
- Squalane: Hydrates without clogging pores—the reason it’s not drying
- Alpha-Arbutin: Fades dark spots by blocking pigment production
- Glycerin: Pulls water into the skin so the C doesn’t just sit on top
Texture is a creamy, pale yellow oil-gel. Absorbs in 30 seconds—leaves a satin finish, not greasy. Smells like a faint, earthy orange peel, not that hot dog water smell of cheap L-ascorbic acid.
Week 3: My foundation stopped oxidizing (turning orange) by noon. That’s the real test of a good C serum. No new breakouts from the squalane, which I was worried about.
Measurably brighter, more even tone in 4 weeks. My chronic post-acne marks faded faster. Zero irritation. Did not magically erase fine lines—that’s not its job.
This is the vitamin C for people who hate finicky, irritating vitamin C. It’s my reliable morning shield.