Peptides are short chains of amino acids marketed to firm skin and soften wrinkles. They are gentle, but most of the evidence comes from small, often manufacturer-funded studies.
What it does
Signal peptides (such as palmitoyl pentapeptide-4, "Matrixyl") are meant to encourage collagen production.
Acetyl hexapeptide-8 ("Argireline") is marketed to soften expression lines.
Copper peptides (GHK-Cu) have been studied for skin repair.
Strength and rules
Usually present in very small amounts; brands rarely disclose them.
How to use it
A gentle anti-ageing option if retinoids are too irritating.
Layers easily with most ingredients.
Who should be careful
Low irritation risk. Expect subtler results than retinoids.
General information, not medical advice. If you have a skin condition or are pregnant, ask your doctor.