What peptides actually do for skin, and what they don't

Signal peptides, carrier peptides, neurotransmitter-inhibiting peptides — a plain explanation of the category, and how to tell a serious formula from a sprinkle.

A peptide is a short chain of amino acids: the same building blocks as the collagen and elastin already in your skin, cut down to a size small enough to be formulated with. Their appeal is that they are messengers rather than blunt instruments — well tolerated, usable alongside almost everything, and suitable for skin that cannot handle retinoids.

Signal peptides, such as palmitoyl tripeptide-1, prompt fibroblasts to increase matrix production. Carrier peptides deliver trace elements like copper that are required as cofactors in tissue repair. Neurotransmitter-inhibiting peptides, of which Acetyl Hexapeptide-8 is the best known, soften the muscle contractions that deepen expression lines over time.

The honest framing is that peptides are cumulative and moderate. They do not resurface skin the way an acid does, and they do not match a prescription retinoid for photoageing. What they do is improve firmness, hydration and line depth gradually, without a tolerance-building period, which makes them unusually easy to stay consistent with — and consistency is where results come from.

How to judge a formula: peptides should sit in the upper half of the INCI list, not below the fragrance. Look for a named peptide rather than an unspecified 'peptide complex'. And check the vehicle — peptides work best in leave-on serums and creams, and are largely wasted in a cleanser that leaves the skin in thirty seconds.

Pairing them is straightforward. Peptides layer comfortably with hyaluronic acid, niacinamide and ceramides. If you also use a strong acid, apply it on alternate nights rather than in the same sitting, since a very low pH environment is not where peptides perform best.