COSRX Pure Vitamin C 23% Serum
Updated Nov 8, 2026 · Top Vitamin C Serum for face
Best for Nobody as a first vitamin C, unless you will keep it cold and finish it fast.
COSRX's 23 percent vitamin C serum. The percentage is high, and that is not an advantage once the formula starts to fail. In Chemist Confessions' three-week heat test it was already more yellow at the start, released gas, ballooned the dropper, and was separating by week three. They were the only bottle that kept doing that. A separating ascorbic-acid serum is oxidized vitamin C. The 13 percent COSRX is the calmer sibling and still needs the same storage rules. Do not buy a 23 percent serum that arrives dark.
What customers like
- Quickly brightens and improves skin tone.
- Noticeable reduction in dark spots and hyperpigmentation.
- Provides a healthy plump glow without being greasy.
- Highly moisturizing enhancing the absorption of other skincare products.
- Smooths and softens the skin effectively.
- Easy to integrate into an existing skincare routine.
What customers dislike
- Unpleasant scent described as coffee beans tuna fish or dog food which may be offputting to some users.
- The scent although shortlived is initially strong.
- Packaging issues reported such as the product arriving halfempty or seeming carbonated upon opening.
- Slow progress in targeting hyperpigmented areas.
- Dose
- 23 percent vitamin C
- Stability
- Separated and gassed in a three-week heat test
- Packaging
- Dropper, which lets in air
Sources: Chemist Confessions: COSRX 23 percent gassed and separated in three weeks · COSRX 23 percent listing
