The Peptide Guide, Signal, Carrier, and Inhibitor Peptides

What peptides are

Peptides are short chains of amino acids, typically 2 to 10, that act as messengers in skin. They can signal fibroblasts to produce more collagen, carry trace minerals to specific cellular sites, inhibit neurotransmitter release at the neuromuscular junction, or compete with biological signaling molecules. The category is broad; specific peptides do specific things.

The four functional families

• Signal peptides, directly stimulate matrix synthesis. Matrixyl (palmitoyl pentapeptide-4) is the most-studied. Research suggests measurable wrinkle reduction in 12-week trials.
• Carrier peptides, deliver trace elements (often copper) to enzymes that need them. GHK-Cu (copper tripeptide) is the canonical example. Research suggests collagen synthesis and wound healing benefits.
• Neurotransmitter-inhibiting peptides, Argireline (acetyl hexapeptide-8) competes with SNARE proteins, reducing muscle contraction. Research suggests modest expression-line improvement.
• Enzyme-inhibiting peptides, interfere with enzymes that degrade matrix or pigment.

How to use

Peptides are generally well-tolerated and pair well with most other actives. They are usually used at relatively low concentrations within a serum; specific percentages depend on the peptide. Layering rules are forgiving, peptides can sit before or after retinoids, vitamin C, niacinamide, and most moisturizers.

What the evidence does and does not say

Research suggests peptides produce real but modest benefits over multi-month timescales. They are unlikely to be the centerpiece of a dramatic transformation; they are credible support actives. The strongest evidence is for matrixyl-class signal peptides for fine line reduction and for copper peptides for wound healing.

Timeline

Most peptide trials show measurable changes at 8 to 12 weeks with peak effect at 6 months. Discontinuation returns the skin to baseline; like most cosmetic-ingredient strategies, peptides require sustained use.