Pentapeptide-18 (Leuphasyl)

Key points

• Leuphasyl is Pentapeptide-18, a cosmetic peptide marketed to reduce the look of expression lines.
• It is often paired with Argireline, working through a slightly different route to ease muscle movement.
• On the skin, with no medicinal claims, it is regulated as a cosmetic ingredient in the UK.
• The evidence is modest, and it is far milder than an injectable treatment.

Quick facts

What it is

Cosmetic skincare peptide (Pentapeptide-18)

Marketed for

Softening expression lines

UK status

Legal as a cosmetic ingredient (no medicinal claims)

Evidence

Modest

How it works

Leuphasyl is used in cosmetics with the aim of calming the small muscle contractions that crease the skin, complementing other peptides such as Argireline. Applied to the surface, its effect is gentle. Most of the supporting evidence is from laboratory and manufacturer studies.

What the evidence shows

There are studies, often from manufacturers, suggesting modest effects on the look of expression lines, especially combined with other peptides. Independent, high quality trials are limited, so claims should be kept modest.

What it does not settle

• Independent high quality evidence is limited.
• Effects are usually modest and build slowly.
• Results depend on the product and how it is used.

Side effects

Common

• Usually well tolerated, though some people get mild irritation or redness. A patch test is sensible.

Report any suspected side effect through the MHRA Yellow Card scheme.

UK legal status and access

As a topical cosmetic ingredient with no medicinal claims, Leuphasyl is legal and widely sold in skincare. Any version sold with medicinal claims, or for injection, would fall under medicines rules.

Common questions