PoreIQTreat & renew · Antioxidants
Vitamin C
An antioxidant that brightens the look of dull skin and dark spots and helps defend against daily environmental stress.
- Also listed as
- L-ascorbic acid, Ascorbic acid, Sodium ascorbyl phosphate
- Best for
- Dullness · Dark spots and uneven tone · Morning routines
- When to use
- AM
- Pairings
- 9 combinations checked
What it is
Vitamin C (most often L-ascorbic acid) neutralizes free radicals from sun and pollution and supports the skin’s own collagen. Pure L-ascorbic acid is effective but unstable and acidic; derivatives are gentler but usually weaker.
Benefits
- Brighter, more even-looking tone
- Fades the look of dark spots over time
- Boosts protection when layered under sunscreen
Watch-outs
- Can sting, especially on sensitive skin
- Oxidizes (turns orange/brown) when exposed to light and air
- Low pH formulas may irritate when layered with other acids
How to use it
Apply in the morning on clean skin, then moisturizer and sunscreen. Store it closed, cool and away from light.
Can you mix vitamin C with…
- Vitamin C + RetinolUse at different timesBoth are strong, and using them back-to-back increases the chance of irritation.
- Vitamin C + Glycolic AcidUse at different timesTwo low-pH products in a row raise the chance of irritation, and vitamin C is best used in the morning anyway.
- Vitamin C + Benzoyl PeroxideUse at different timesBenzoyl peroxide is an oxidizer and can reduce the effectiveness of vitamin C.
- Vitamin C + Salicylic AcidUse with cautionBoth are acidic.
- Vitamin C + PeptidesUse with cautionMost peptides are fine with vitamin C, but copper peptides may be less stable next to strong acids and vitamin C.
- Vitamin C + NiacinamideWorks well togetherAn old myth says they cancel each other out.
- Vitamin C + Hyaluronic AcidWorks well togetherHyaluronic acid adds hydration and can make vitamin C feel less tingly.
- Vitamin C + Zinc OxideWorks well togetherAntioxidants like vitamin C complement sunscreen.
- Vitamin C + Tranexamic AcidWorks well togetherBoth target the look of dark spots in different ways and are commonly combined.
Frequently asked questions
What does vitamin C do for skin?
An antioxidant that brightens the look of dull skin and dark spots and helps defend against daily environmental stress.
Should I use vitamin C in the morning or at night?
Morning is the most common choice, because its antioxidant effect pairs well with sunscreen during the day.
My vitamin C serum turned brown. Is it still good?
A dark orange or brown color usually means it has oxidized and lost potency. It is best to replace it.
Related guides
- Skincare Routine Order: What to Apply First (AM and PM)
- How to Start Using Retinol Without Irritation (Beginner Schedule)
- A Minimal Skincare Routine for Beginners (3 Steps)
Similar ingredients
General cosmetic information, reviewed against public guidance such as the American Academy of Dermatology. Patch test new products. For medical concerns, see a dermatologist. Last updated 2026-10-22.