Acetyl hexapeptide-8 vs Pentapeptide-18
It is a cream ingredient sold as a needle-free way to smooth expression lines. Two small trials disagreed: one showed less wrinkling, one showed none. It is a cream ingredient sold as a Botox alternative for expression lines. Two small studies of 20 people each had no comparison group, so the proof is weak.
Acetyl hexapeptide-8 has the stronger evidence, grade B (some human evidence) against grade C for Pentapeptide-18. Neither is FDA approved.
Evidence
BSome human evidence
CAnimal and cell studies
Human studies cited
Animal or cell studies cited
Why the grade
For wrinkle reduction there is one randomized placebo-controlled trial in 60 Chinese adults showing a benefit, a 19-person split-face double-blind study showing none, a 26-patient uncontrolled series and the manufacturer's original volunteer study. Skin penetration work in human and animal skin finds very little of the peptide reaches the dermis, which leaves the mechanism in doubt. Small samples and conflicting results keep this at B.
The human evidence is two small uncontrolled studies: a 20-volunteer, two-month test of pentapeptide-18 creams at three strengths, in which only the strongest reduced measured wrinkle length, and an eight-week test in 20 women of a cream that also contained retinol. Neither had a vehicle or placebo control, and the manufacturer has not published its own trial data. Uncontrolled series put it at C for expression lines.
FDA
Cosmetic ingredient
Acetyl hexapeptide-8 (Argireline) is a cosmetic ingredient, and the FDA does not approve cosmetic ingredients before sale; products containing it are regulated as cosmetics so long as they claim only to improve appearance. It is not an approved drug for any use.
Cosmetic ingredient
Pentapeptide-18 is a cosmetic ingredient, sold under the trade name Leuphasyl. Cosmetic ingredients in the United States are not reviewed or approved by the FDA before sale, so there is no FDA approval to cite for or against it.
Sold for
Argireline is marketed as a needle-free alternative to Botox that relaxes expression lines when applied as a cream or serum.
Pentapeptide-18 is sold as a topical alternative to botulinum toxin that softens expression lines, usually paired with acetyl hexapeptide-8 (Argireline).
Studies say
One small randomized trial found a measurable reduction in eye-area wrinkles and another found none, while penetration studies show almost none of the peptide reaches the muscle layer, so the evidence supports a modest surface effect at best (grade B).
Two small uncontrolled studies in 20 volunteers each report shorter or fewer wrinkles after weeks of use, one of them with retinol in the same cream, which is grade C support at best.
Class
Neurotransmitter-inhibiting peptide
Neurotransmitter-inhibiting peptide
Route
Topical
Topical