Peptides in skincare: what actually works

Four broad families

Signal peptides tell skin cells to produce more structural protein. Carrier peptides deliver trace elements such as copper to where they are used — GHK-Cu belongs here. Neurotransmitter-inhibiting peptides aim to reduce the muscle contraction behind expression lines. Enzyme-inhibiting peptides slow the breakdown of existing collagen.

The delivery problem

Peptides are relatively large, water-loving molecules, and the outer layer of skin is built specifically to keep such things out. Formulation matters enormously — the same peptide in two different bases can behave very differently. This is why ingredient lists alone tell you less than people assume.

Where the evidence is strongest

Copper peptides and matrixyl-type signal peptides have the most published support for firmness and fine lines. The effect sizes are real but modest, and they take months. Anything promising a dramatic change in weeks is selling something.

Building a routine

Sunscreen daily does more than every peptide combined. A retinoid at night has the largest evidence base of any active. Peptides sit sensibly alongside both as a well-tolerated addition, particularly for people whose skin cannot handle stronger actives.