The Comparison, in One Table
| Vitamin C (L-ascorbic acid) | Copper peptides (GHK-Cu) | |
|---|---|---|
| What it is | An antioxidant vitamin | A carrier peptide that delivers copper |
| Main goal | Antioxidant protection, brightening, collagen support | Repair, firmness, skin remodeling |
| Evidence base | Large, including stabilized-formula research | Long research history, largely laboratory and wound-healing |
| Best time of day | Morning, under sunscreen | Evening |
| Stability | Unstable; oxidizes | Can be sensitive to acids and other actives |
| Irritation | Can sting at low pH | Usually gentle |
What Each One Does
Vitamin C is an antioxidant that neutralizes free radicals from sunlight and pollution, supports collagen production and fades uneven pigment. In its pure form it needs a low pH to penetrate and oxidizes quickly once opened. Forms and trade-offs: L-ascorbic acid vs. THD ascorbate.
Copper peptides — usually copper tripeptide-1, also called GHK-Cu — carry copper into the skin. The peptide was first isolated in the 1970s and has a long research history in wound healing and tissue repair; reviews describe effects on collagen, elastin and skin remodeling. Much of that work is laboratory or wound-focused, so its size in everyday cosmetic use is less certain. More on peptides: best peptide serums.
Using Both: The One Rule
If you only buy one, vitamin C is the better-evidenced daytime active and pairs naturally with sunscreen. Copper peptides are a reasonable evening addition for someone whose routine already includes sunscreen, a retinoid or vitamin C, and a moisturizer. Copper peptides also sit awkwardly next to strong acids, so keep exfoliation on separate nights.
