Signal Peptide

Peptides

Peptides are short amino acid chains that act as cell-signalling molecules. In skincare, they are used to stimulate collagen production, support barrier repair, and reduce fine line appearance. Evidence is moderate for specific peptides but marketing often overstates their effects.

topicalanti-ageingbarrier support

Moderate Evidence

Last reviewed: March 2026 · Our methodology

What It Does

Peptides work primarily as signalling molecules. When applied topically, specific peptide sequences can communicate with skin cells to modulate their behaviour. The three main categories used in skincare are:

Signal peptides (e.g. palmitoyl pentapeptide-4 / Matrixyl) — Stimulate fibroblasts to produce collagen and elastin. The most studied category for anti-ageing.

Carrier peptides (e.g. copper tripeptide-1 / GHK-Cu) — Deliver trace elements (typically copper) to cells, supporting wound healing and collagen remodelling. Copper peptides are among the most evidence-backed peptides.

Neurotransmitter-inhibiting peptides (e.g. acetyl hexapeptide-3 / Argireline) — Marketed as “Botox alternatives” that reduce expression lines by inhibiting neurotransmitter release at the neuromuscular junction. Effects are mild at best — they cannot replicate the mechanism of injectable neurotoxins.

A critical nuance: many peptides have difficulty penetrating the stratum corneum due to their size and charge. Formulation (particularly liposomal delivery and fatty acid conjugation like palmitoylation) significantly affects whether peptides reach their target cells.

Best Use Cases

Fine lines and early wrinkles (as part of a broader anti-ageing routine)
Barrier repair support
Post-procedure skin recovery
Complementing retinoid use (different collagen-stimulating mechanism)

Who May Benefit Most

People seeking anti-ageing support who cannot tolerate retinoids, those looking for a gentler collagen-stimulating approach, and anyone in a post-procedure recovery phase. Peptides work best as part of a comprehensive routine rather than as standalone anti-ageing treatment.

Cautions

Generally very well tolerated. Irritation is rare. Copper peptides may cause mild irritation in some individuals. The main risk is financial — peptide serums are often expensive, and expectations should be calibrated to the moderate evidence base.

Common Mistakes

Expecting peptides to match retinoid efficacy — they are gentler but less potent
Using copper peptides with vitamin C in the same step (copper can oxidise ascorbic acid)
Paying premium prices for peptides with minimal evidence (especially 'Botox-like' claims)
Using peptides with strong exfoliants in the same step — acids can break peptide bonds
Not reading beyond marketing — ask 'which specific peptide, at what concentration, with what evidence?'

Combines Well With

Hyaluronic acid (hydration + peptide signalling)
Niacinamide (barrier support + peptide signalling)
Retinoids (different collagen pathways — on alternate nights or AM peptide / PM retinoid)
Ceramide moisturisers (seal peptides in)

May Combine Poorly With

Vitamin C (specifically with copper peptides — copper can oxidise L-ascorbic acid)
Strong AHAs/BHAs in the same step (low pH may denature peptide bonds)
Benzoyl peroxide (may degrade some peptide structures)

Realistic Timeline

Effects are subtle and gradual. Texture and hydration improvements may be noticeable within 4–8 weeks. Meaningful wrinkle reduction (if any) typically requires 3–6+ months of consistent use. Expectations should be modest.

Disclaimer

Peptide research is promising but still developing. Many marketed peptide claims are based on in vitro studies that may not translate to real-world topical results. Retinoids remain the gold standard for evidence-based anti-ageing.