Peptide education
Pentapeptide-18
Pentapeptide-18 is a synthetic five-residue peptide used in cosmetics for the appearance of facial lines. Its sequence contains D-alanine.
A small emulsion study reported changes in wrinkle measurements without a described placebo group. Another study combined the peptide with retinol.
Overview
Quick answer
Pentapeptide-18 is not botulinum toxin. Cosmetic measurements do not establish an equivalent effect on facial muscles.
Is it the same as acetyl hexapeptide-8?
No. They are different peptides with different sequences.
Does it relax facial muscles like botulinum toxin?
The cited cosmetic studies did not establish an equivalent neuromuscular effect.
What did the emulsion study measure?
Twenty volunteers used test emulsions for two months. Investigators used two-dimensional images and reported shorter wrinkle trajectories with the highest tested commercial ingredient level.
Evidence
Evidence snapshot
The report described changes from baseline without a placebo comparison.
The peptide and retinol were not tested separately in the finished formulation.
Claims
Common claims vs evidence
| Claim | Human evidence | Mechanistic evidence | Verdict |
|---|---|---|---|
| Pentapeptide-18 is equivalent to botulinum toxin. | The cited formulation studies did not compare it with injected botulinum toxin. | They did not establish a direct effect on facial neuromuscular transmission. | Equivalent clinical effects are not established. |
Bottom line
Main takeaway
A cosmetic peptide is different from an injected medicine.
The percentage of a commercial peptide solution may not be the percentage of pure peptide.
Controlled ingredient-specific studies are needed to separate peptide effects from vehicle and retinol.
Identity
What it is
The sequence is Tyr-D-Ala-Gly-Phe-Leu, with D-alanine in the second position.
It is an enkephalin analog, not the same molecule as the natural peptide or botulinum toxin.
Research
Research evidence
One small study examined peptide-containing emulsions without a described placebo comparison. Another tested the peptide together with retinol.
| Study / evidence area | Population | Design | Product context | Main outcome | Limitations | Weight |
|---|---|---|---|---|---|---|
| Commercial ingredient emulsion study | 20 volunteers aged 30 or older | Two-month study of three emulsion strengths | Emulsions made with a commercial pentapeptide ingredient | Authors reported reduced wrinkle trajectory measurements with the highest tested ingredient level. | No placebo group was described; allocation details were unclear and the two-dimensional method did not measure depth. | Limited uncontrolled formulation evidence |
| Retinol and peptide cream study | Two panels of 20 women each, with ages 30 to 65 in the anti-aging panel and 18 to 65 in the anti-acne panel | Cream and base-formulation comparisons over 8 weeks | Lipid carriers containing both retinol and pentapeptide-18 added to anti-aging or anti-acne creams, compared with their respective base creams | The authors reported changes in skin measurements with the combined preparation. | Retinol, peptide, and delivery system were not separated; some authors worked for the manufacturer. | Limited combined-product evidence |
Use context
Reported use context
The emulsion study used a specific facial formulation for two months.
Study and label context
Volunteers applied the tested emulsion daily for two months.
The report described percentages of a commercial ingredient; these do not establish pure peptide concentration. This is not a recommendation.Cautions
Safety and unknowns
- The small, short studies cannot exclude uncommon reactions or establish long-term safety.
- The tolerability of a finished product also depends on its other ingredients.
Product quality
Product identity and quality
Check whether a stated percentage refers to a diluted commercial ingredient or to pure peptide.
Ingredient identity
Pentapeptide-18 and acetyl hexapeptide-8 are different peptides.
Concentration basis
Commercial peptide solutions can contain carriers as well as the peptide.
Other actives
A cream containing retinol cannot isolate the peptide's effect.
Mechanism
How it is proposed to work
The ingredient was designed as an enkephalin analog, but a proposed signaling mechanism does not establish muscle relaxation after skin application.
The cited cosmetic studies did not measure an isolated effect at the facial neuromuscular junction.
Details
Technical details
Sources
References
- 1.
Cosmetics. The Efficiency and Safety of Leuphasyl - A Botox-Like Peptide
doi:10.3390/cosmetics1020075
A 20-volunteer, two-month study of three emulsions using a commercial ingredient; no placebo comparison was described.
- 2.
PubMed Central. Retinol and Oligopeptide-Loaded Lipid Nanocarriers as Effective Raw Material in Anti-Acne and Anti-Aging Therapies
doi:10.3390/life14101212 PMID:39459512
Human formulation research used pentapeptide-18 together with retinol; the two ingredients were not isolated.
- 3.
PubChem. Acetyl hexapeptide-3
Chemical record lists acetyl hexapeptide-8 among the names for a different peptide.
- 4.
FDA. Is It a Cosmetic, a Drug, or Both? (Or Is It Soap?)
US product classification depends on intended use.