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The Cast Index

Ingredient library / Signal and conditioning molecules

Peptides.

Also on labels as: Palmitoyl tripeptide · Palmitoyl pentapeptide-4 · Acetyl hexapeptide-8 · Copper peptides

Quick answer

What is peptides?

Peptides are short chains of amino acids. In cosmetics they are used to condition skin, lips, lashes and hair, and some are marketed as “signal” peptides for the look of firmness. Evidence varies widely between specific peptides, so treat broad claims cautiously and judge each formula on its full ingredient list.

What it does

  • Conditions and softens lips, skin and hair in many formulas
  • Some peptides are studied for the appearance of fine lines, with mixed evidence
  • Hair “bond” and repair treatments use peptide technology to condition damaged hair

Who it suits

Most people; peptides are generally gentle and suit sensitive skin.

How to use it

  1. Use as directed — peptides appear in serums, lip treatments, masks and hair treatments
  2. Layer skincare peptides before moisturiser

Take care

  • Evidence differs by peptide; brand claims are often based on the brand’s own studies
  • Some brands advise against mixing copper peptides with strong acids or vitamin C

What it pairs with

Generally compatible with hydrators and moisturisers. Follow product directions on combining with acids or vitamin C.

General information, not medical advice. For a skin condition, pregnancy or persistent irritation, speak to a pharmacist, GP or dermatologist.

In the catalogue

Products listing peptides.

Named in each brand’s own listing

Read further

Sources.

  1. Ferreira et al., “Cosmeceutical Peptides in the Framework of Sustainable Wellness Economy”, Frontiers in Chemistry, 2020 ↗

Peptides, answered

Do peptides really work?

It depends on the peptide. Some have published studies, often small or brand-funded; others have little evidence. They are generally gentle conditioning ingredients.

Why are peptides in lip products?

They are used as conditioning ingredients alongside emollients such as shea butter to keep lips feeling soft and smooth.