Barrier & repair· in 6 products

Peptides

Also listed as Palmitoyl pentapeptide-4 (Matrixyl), Palmitoyl tripeptide-1, Acetyl hexapeptide-8 (Argireline) and Palmitoyl tetrapeptide-7

Emerging evidence Parts per million to a few percent of a peptide complex; brands rarely disclose exact levels

Peptides are short chains of amino acids used in anti-aging serums and creams. Different peptides are marketed as signal, carrier, enzyme-inhibiting or neurotransmitter-modulating ingredients.

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6PePeptidesBarrier & repair

What it does

The short version.

Signal peptides such as palmitoyl pentapeptide-4 are designed to mimic fragments of collagen and prompt skin cells to make more matrix proteins in lab studies. Neurotransmitter-modulating peptides such as acetyl hexapeptide-8 are marketed as gentle 'Botox-like' ingredients, though their effect on expression lines in vivo is modest. Most peptides are also good humectant and conditioning agents, so they improve the feel of skin even when their headline mechanism is unproven at the concentrations used.

Emerging evidence

Lab data are strong for some peptides, but clinical trials are mostly small, short and sponsored by ingredient suppliers, and penetration of larger peptides into skin is limited.

In our directory: It’s a key ingredient in 6 products we review, most often treatments and moisturizers. Those products are mostly built for hydrating, smoothing and firming. In formulas, it most often shares the label with glycerin, copper peptides and hyaluronic acid.

Reach for it for

Fine lines Firming Hydrating Smoothing

Usually a good fit for

All skin types Mature skin Dry skin Sensitive skin

How to use it

Getting it right.

Use a peptide serum or cream once or twice daily after cleansing. Peptides are gentle and can be layered with most routines, including on nights you skip retinoids.

Layering

Friends & frenemies.

Pairs well with

Hyaluronic acid Niacinamide Retinol Ceramides Vitamin C

Go slow with

Glycolic acid

Not forbidden — just easier to over-do. Alternate nights or separate morning and evening.

Before you start

Generally well tolerated. Very low-pH acids may degrade some peptides in the same formula or layer, so apply strong acids at a different time. Peptides are not a substitute for sunscreen or retinoids.

References

Educational, not medical advice. Ingredient guides summarise published research and expert guidance; formulas and concentrations differ between products.