Ingredient Guide

Pentapeptide-18

Also known as: Pentapeptide-18, Leuphasyl

All skin types

What It Is

A 5-amino-acid peptide designed to target expression-related wrinkles through a complementary mechanism to acetyl hexapeptide-8. It is the active ingredient in the commercial peptide Leuphasyl®.

What It Does

Works by modulating enkephalin receptors (opioid pathway) to reduce muscle contraction-triggering signals — a different mechanism from Argireline, allowing a synergistic approach when used together for expression line reduction.

Best For

Expression linesFrown linesMulti-peptide anti-aging approach

Benefits

  • Complementary mechanism to Acetyl Hexapeptide-8 — targeting a different step in muscle contraction signaling
  • Combined use with Argireline provides a broader anti-expression-line approach
  • Well tolerated with excellent safety profile

When to Be Careful

  • Like all expression-reducing peptides — subtle, accumulative effects vs. dramatic immediate results
  • Requires consistent use
ItGirlies Ingredient Intelligence
Why This Gets Hype

Works alongside Argireline (acetyl hexapeptide-8) for a synergistic dual-peptide expression line approach. Formulas combining both are considered among the more sophisticated peptide anti-aging approaches.

What People Often Misunderstand

Pentapeptide-18 works through the opioid receptor pathway — not in the way opioid drugs work systemically. The term sounds alarming but the cosmetic action is limited to localized muscle signaling at the application site.

Best Routine Slot

Part of a multi-peptide serum — morning or evening, consistently.

Good Match For

Acetyl Hexapeptide-8, Palmitoyl Tripeptide-38, Palmitoyl Tripeptide-1

Proceed Carefully If…

No known significant topical concerns.

Signs You May Be Overdoing It

Peptides do not cause overuse irritation.

Commonly Found In

Multi-peptide anti-aging serums

FAQs About Pentapeptide-18

What does pentapeptide-18 do?
It targets the enkephalin receptor pathway to reduce the nerve signals that trigger repetitive facial muscle contractions — complementing the SNARE-complex mechanism of Acetyl Hexapeptide-8 for a dual anti-expression-line approach.