Peptides are among the harder ingredients to shop for, because the word covers dozens of different molecules that do different things – and the marketing rarely tells you which one you're buying. Here's a straightforward guide.
What peptides are
Proteins are long chains of amino acids. Peptides are short chains of the same building blocks — typically a handful of amino acids linked together. Because they're small, they can be formulated to sit on or within the upper layers of the skin.
The important thing to understand is that "peptide" is a category, not an ingredient. Signal peptides, carrier peptides and neuropeptides all appear in skincare and behave differently, which is why two peptide serums can produce quite different results.
What they're used for
In cosmetic skincare, peptides are chosen for the appearance of firmness, smoothness and the look of fine lines. Skin often looks more supple and better conditioned with sustained use.
Two honest points. First, peptide research is genuinely promising but varies enormously by specific peptide and formulation — a product's results depend on which peptides it uses and at what level, not on the word appearing on the label. Second, this is a slow ingredient: expect gradual change over months, not weeks.
Who they suit
Peptides are gentle, don't cause photosensitivity, and rarely irritate — which makes them a genuine option for people who can't tolerate retinol. They're also a sensible choice during pregnancy when many actives are restricted, though as always check with your GP or midwife about anything you're using regularly.
If you can tolerate retinol, it remains the more researched choice for the appearance of lines and texture. Many people use both — peptides in the morning, retinol at night.
How to use them
Peptide serums go on after cleansing, before heavier creams. Morning or evening both work.
They pair well with hyaluronic acid, niacinamide, ceramides and squalane. There's a longstanding suggestion that direct acids may affect certain peptides, so if you use both, applying them at different times of day is a sensible precaution rather than a strict rule.
Consistency matters more than anything with peptides. They reward daily use over months; used occasionally, they'll do very little.
Explore our peptide skincare, or see all active skincare.