Quick Comparison

AllantoinCopper Peptides (GHK-Cu)
Typical ConcentrationConcentrations: 0.5-2% in most formulations. Often combined with other soothing ingredients. Apply as part of regular skincare routine. Safe for all ages and skin types, including infants.Concentrations: 0.1-1% in skincare products. Apply once or twice daily. Do NOT use with strong acids (vitamin C at low pH, AHAs) — copper can catalyze free radical formation with ascorbic acid. Best used as a standalone PM treatment or mixed with peptide serums.
ApplicationTopical (cream, lotion, serum, ointment). Compatible with all other skincare ingredients.Topical (serum, cream). Blue/copper-colored products. Do not combine with low-pH vitamin C.
Research Papers8 papers10 papers
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Mechanism of Action

Allantoin

Allantoin (5-ureidohydantoin) stimulates cell proliferation and tissue regeneration by promoting fibroblast activity, keratinocyte proliferation, and extracellular matrix synthesis including collagen and glycosaminoglycans. It acts as a mild keratolytic by promoting the natural desquamation process—loosening corneocyte adhesion and facilitating shedding—without the irritation, pH disruption, or barrier compromise associated with alpha- or beta-hydroxy acids. Allantoin has anti-inflammatory properties through modulation of prostaglandin synthesis (inhibiting COX-2 and reducing PGE2) and may downregulate pro-inflammatory cytokines. Its moisturizing effect comes from increasing the water-binding capacity of the extracellular matrix and stratum corneum; it is highly soluble and forms hydrogen bonds with water. Allantoin also promotes wound epithelialization. Its safety profile—non-irritating, non-sensitizing, non-comedogenic—makes it suitable for compromised skin, post-procedure care, and infant formulations.

Copper Peptides (GHK-Cu)

GHK-Cu activates wound repair genes through copper-dependent transcription factor modulation. It stimulates fibroblasts to produce collagen types I, III, and V via COL1A1, COL3A1, COL5A1 upregulation, plus elastin, decorin, and glycosaminoglycans. Copper serves as cofactor for lysyl oxidase (collagen cross-linking). It attracts macrophages and mast cells releasing PDGF, TGF-beta, FGF. Promotes angiogenesis via VEGF. Uniquely activates MMP-2 and MMP-9 to break down damaged collagen and scar tissue — supporting healthy remodeling. Balanced anabolic-catabolic activity explains efficacy in anti-aging and scar revision. Avoid with vitamin C: copper catalyzes Fenton reactions oxidizing ascorbic acid.

Risks & Safety

Allantoin

Common

None. Allantoin is non-irritating, non-sensitizing, and non-comedogenic.

Serious

None.

Rare

Allergic reaction is extremely rare.

Copper Peptides (GHK-Cu)

Common

Blue/green tint to product (normal — copper color). Mild irritation.

Serious

Can be pro-oxidant when combined with vitamin C — avoid concurrent use.

Rare

Allergic reaction to copper.

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