Argireline (Acetyl Hexapeptide-8): a formulator’s reference

What Acetyl Hexapeptide-8 is

Argireline is the trade name; Acetyl Hexapeptide-8 is the INCI name, and the one that goes on an ingredient list. The material is a synthetic six-residue peptide, acetylated at the N-terminus and amidated at the C-terminus, with the sequence Ac-Glu-Glu-Met-Gln-Arg-Arg-NH₂ — written Ac-EEMQRR-NH₂ in one-letter code. Older documentation calls the same substance Acetyl Hexapeptide-3; the CAS number, 616204-22-9, is shared, and the Cosmetic Ingredient Review explicitly treats “Acetyl Hexapeptide-8 Amide” as synonymous with Acetyl Hexapeptide-8. If you are reading a supplier document from before roughly 2010, expect the older name.

The sequence is not arbitrary. It was patterned after the N-terminal domain of SNAP-25, one of the three proteins that assemble into the SNARE complex — the machinery a nerve terminal uses to fuse a vesicle with its membrane and release neurotransmitter. That is the same machinery botulinum neurotoxin type A cleaves, which is where the persistent “topical Botox” framing comes from. The peptide was identified through a rational design programme and introduced in a cosmetic-science journal in 2002.

One practical note before anything else: most trade material is supplied as a dilute aqueous or glycerin solution, not as neat peptide. A supplier recommending “5–10%” is usually recommending 5–10% of that solution, which contains a small fraction of a percent of actual peptide. Material bought as a lyophilised powder is the peptide itself, and the two are not interchangeable at the same number.

Reference data

Identity data only, from the public chemical record and the primary literature. Anything we could not source is left out rather than filled in.

A correction worth knowing about

The PubChem record for CAS 616204-22-9 (CID 71587772, titled “Acetyl hexapeptide-3”) reports the formula C₃₅H₆₂N₁₄O₁₁S and a molecular weight of 887.0 g/mol. Those figures do not correspond to Ac-EEMQRR-NH₂. Inspecting the deposited structure shows why: the first peptide bond is drawn as an enamine rather than an amide, so the record describes a molecule that is not the peptide. The formula and mass in the table above are computed from the sequence given in the primary literature instead. We flag this rather than reproducing the database value, because a mass-spectrometry identity check run against 887.0 would be checking against the wrong number.

Use concentration — what is documented

This is the single question a formulator most wants answered, and the honest answer is that two numbers exist, they differ by more than three orders of magnitude, and they come from different kinds of source.

• 10% in the founding study. Blanes-Mira et al. (2002) reported skin-topography analysis of an oil-in-water emulsion containing 10% of the hexapeptide, applied for 30 days to healthy female volunteers, with wrinkle depth reduced by up to 30%. That is a study concentration, not an industry norm.
• 0.005% in actual industry practice. The Cosmetic Ingredient Review Expert Panel’s 2025 safety assessment concluded that Acetyl Hexapeptide-8 Amide is safe in cosmetics in the present practices of use at concentrations up to 0.005%, and that the available data are insufficient to determine safety above that. The 0.005% figure reflects what the industry reported actually using in the concentration-of-use survey the panel worked from.

Both statements are accurate and neither is the whole picture. The gap between them is worth sitting with: the concentration at which an effect was reported in 2002 is roughly two thousand times the concentration the industry reported using in 2025, and no safety conclusion currently supports the higher figure. A formulator who wants to reproduce the 2002 exposure is outside the range the CIR was able to assess. That is a compliance decision, not a chemistry one, and it belongs to whoever puts the product on a market.

What the mechanism actually is, and where it stops

The in-vitro pharmacology is the strongest part of this ingredient’s story. Blanes-Mira et al. (2004, J Neurochem) showed that small peptides patterned after the SNAP-25 N-terminal domain inhibit SNARE-complex assembly and regulated exocytosis. The 2002 paper reported that the hexapeptide inhibited neurotransmitter release with a potency similar to botulinum neurotoxin A, while being much less efficacious than the toxin — a distinction that gets lost in marketing but matters: similar potency at the target is not the same as similar effect.

Where the chain of reasoning breaks is delivery. Acetyl Hexapeptide-8 is hydrophilic and, by peptide standards, large. A 2025 review devoted specifically to its permeability and efficacy concluded that its limited passage through the lipophilic stratum corneum makes dermal delivery challenging, that formulation strategies such as oil-in-water and water-in-oil-in-water emulsions have been explored to improve it, and that the ability of the peptide to reach neuromuscular junctions remains uncertain. A broader 2022 review of anti-wrinkle peptides reached the same conclusion for the class: most are not good candidates for skin permeation, and cellular efficacy without permeation is, in the authors’ framing, useless.

So: a well-characterised in-vitro mechanism, and an unresolved question about whether the molecule ever gets to where that mechanism operates. Any claim that skips over the second half is skipping the hard part.

The clinical evidence, and who ran it

Reported plainly, in order of how much weight each study can carry.

The independent negative study

Henseler (2023) recruited nineteen female participants and ran a double-blind, split-face design: the same hyaluronic-acid serum was applied to both sides of the face for four weeks, one side’s container containing Argireline and the other not, with neither participants nor investigator knowing which. Wrinkle scores decreased slightly on both sides, but not significantly, and the comparison between the Argireline side and the control side showed no significant difference in wrinkle score or in the camera system’s TruSkinAge measure. The author’s stated conclusion is that the effect of Argireline was not proven and that it is not deemed an alternative to botulinum toxin. It is a small study, four weeks long, and one investigator — but it is the design that most directly isolates this ingredient, it was independent of the ingredient supplier, and it is negative.

The founding study

Blanes-Mira et al. (2002) is the paper every supplier document traces back to. It reported up to 30% wrinkle-depth reduction from a 10% emulsion over 30 days, alongside the mechanistic work. It was published in a cosmetic-science journal, and the peptide was, in the paper’s own words, identified through a rational design programme — that is, the study introducing the ingredient came from the group that designed it. That does not make it wrong; it does mean it is not independent replication.

Comparative and combination studies

• Aruan et al. (2023) — a double-blind randomised trial in 21 Indonesian women split across three arms (Acetyl Hexapeptide-3 cream, Palmitoyl Pentapeptide-4 cream, placebo) for eight weeks. That is roughly seven subjects per arm. The authors reported that the palmitoyl pentapeptide appeared to perform better, and described their own work as an initial study warranting a more adequate sample size.
• Zhu et al. (2026) — an ex-vivo study plus two clinical studies (n = 50 and n = 42) of a serum containing acetyl hexapeptide-8 together with dipeptide diaminobutyroyl benzylamide diacetate, gluconolactone, niacinamide and laminaria extract. Statistically significant improvements were reported for the finished serum. All authors were employed by L’Oréal, and because the formula contains five actives, nothing in the result can be attributed to any one of them.

Read together: the positive human data comes from parties with a commercial interest or from products in which this peptide is one ingredient among several; the one independent, well-controlled, ingredient-isolating test is negative. That is the state of the evidence, and a formulator planning label copy should plan around it.

Formulation and stability constraints

We have not found published stability data for Acetyl Hexapeptide-8 in a finished cosmetic base — no pH-stability curve, no accelerated-ageing dataset, no preservative-compatibility study. Rather than invent one, here is what can actually be said, with the basis for each statement named.

• Copper interaction (measured). Wyrzykowski et al. (2024, J Pept Sci) studied the Cu(II)-chelating properties of Argireline and three derivatives by potentiometric titration and isothermal titration calorimetry, describing the peptide as having a proven affinity for copper(II) ions. If this peptide shares a phase with a copper-peptide ingredient such as GHK-Cu or AHK-Cu, that is a real interaction to characterise, not a theoretical one.
• Methionine (general peptide chemistry). The sequence contains one methionine, the residue most susceptible to oxidation in peptide chemistry generally. We are stating a class property, not a measurement on this ingredient — but it is the residue an oxidative-stability study would look at first.
• Charge and solubility. Two glutamate and two arginine residues make the molecule strongly hydrophilic and ionisable, which is why it dissolves easily in the water phase and, per the permeability literature, why it stops at the stratum corneum.
• Proteolysis in skin. Cosmeceutical peptides are substrates for skin proteases; a 2021 LC-MS/MS method paper built a dermal-stability assay for exactly this reason using pal-KTTKS as its reference peptide. No equivalent published figure for Acetyl Hexapeptide-8 was found.

Storage of the raw material

As supplied, the material is a lyophilised powder and is handled like any research-grade peptide powder: kept dry, kept cold, kept away from light, and protected from repeated warming to room temperature and back, since condensation into a hygroscopic powder is the usual way a good vial goes bad. See how to store peptides for the general handling logic; nothing about this molecule changes it.

Verifying identity and purity

Two analyses answer the two questions that matter for a raw peptide. Mass spectrometry answers “is this the right molecule?” by comparing the measured mass against the mass expected from Ac-EEMQRR-NH₂ — approximately 889 Da average. HPLC answers “how much of this is that molecule?” and reports it as a purity percentage, with the remainder being synthesis-related impurities, truncated sequences, counter-ion and residual solvent.

The PubChem discrepancy described above matters here in a practical way: if you check a certificate’s measured mass against the database figure of 887.0 rather than against the sequence-derived ~889, you will be comparing to a number that describes a different structure. Check against the sequence. How to verify peptide purity and how to read a COA cover what each line on a certificate is telling you, and any batch we ship can be looked up on verify.

What is not established

Stated directly, because the rest of the internet on this ingredient does not.

• That topically applied Acetyl Hexapeptide-8 reaches a neuromuscular junction in intact human skin at a concentration where its in-vitro mechanism operates. A 2025 review specific to this peptide describes that as uncertain.
• That it produces a wrinkle effect distinguishable from vehicle in an independent, ingredient-isolating trial. The one such trial we found reported no significant difference.
• That it is equivalent, comparable or an alternative to botulinum toxin. That framing traces to a mechanistic resemblance in vitro, and the author of the split-face study explicitly rejected the equivalence.
• Any safety conclusion above 0.005%. The CIR panel stated the available data were insufficient to make that determination.
• Any published stability, pH-compatibility or preservative-interaction dataset for the ingredient in a finished cosmetic base. If a supplier has one, it is not in the indexed literature.

Sourcing and related ingredients

Acetyl Hexapeptide-8 is supplied as a raw material with a per-batch Certificate of Analysis reporting HPLC purity and mass-spectrometric identity confirmation. It is not supplied as a finished cosmetic, and a Certificate of Analysis is not a cosmetic safety assessment — a finished product needs its own stability, preservative-efficacy and safety work under the rules of wherever it is sold.

Closely related material on this site: SNAP-8 (Acetyl Octapeptide-3) is an extended analogue of this same sequence and is the ingredient most often positioned as its successor; SYN-AKE targets the same neuromuscular idea from a completely different chemical direction. The full ingredient list, with live availability, is on the cosmetic ingredient hub, and the separate research-compound catalogue is at /catalog.

Frequently asked questions

Literature cited

1. Blanes-Mira C, Clemente J, Jodas G, et al. “A synthetic hexapeptide (Argireline) with antiwrinkle activity.” Int J Cosmet Sci. 2002;24(5):303–310. PMID 18498523. pubmed.ncbi.nlm.nih.gov/18498523.
2. Blanes-Mira C, Merino JM, Valera E, et al. “Small peptides patterned after the N-terminus domain of SNAP25 inhibit SNARE complex assembly and regulated exocytosis.” J Neurochem. 2004;88(1):124–135. PMID 14675156. pubmed.ncbi.nlm.nih.gov/14675156.
3. Johnson W Jr, Bergfeld WF, Belsito DV, et al. “Safety Assessment of Acetyl Hexapeptide-8 Amide as Used in Cosmetics.” Int J Toxicol. 2025;44(2_suppl):54S–63S. PMID 40673537. pubmed.ncbi.nlm.nih.gov/40673537. (Cosmetic Ingredient Review; source of the 0.005% conclusion.)
4. Henseler H. “Investigating the effects of Argireline in a skin serum containing hyaluronic acids on skin surface wrinkles using the Visia® Complexion Analysis camera system for objective skin analysis.” GMS Interdiscip Plast Reconstr Surg DGPW. 2023;12:Doc09. PMID 38024099. pubmed.ncbi.nlm.nih.gov/38024099. (Independent double-blind split-face study; negative result.)
5. Zdrada-Nowak J, Surgiel-Gemza A, Szatkowska M. “Acetyl Hexapeptide-8 in Cosmeceuticals—A Review of Skin Permeability and Efficacy.” Int J Mol Sci. 2025;26(12):5722. PMID 40565185. pubmed.ncbi.nlm.nih.gov/40565185.
6. Mortazavi SM, Moghimi HR. “Skin permeability, a dismissed necessity for anti-wrinkle peptide performance.” Int J Cosmet Sci. 2022;44(2):232–248. PMID 35302659. pubmed.ncbi.nlm.nih.gov/35302659.
7. Aruan RR, Hutabarat H, Widodo AA, et al. “Double-blind, Randomized Trial on the Effectiveness of Acetylhexapeptide-3 Cream and Palmitoyl Pentapeptide-4 Cream for Crow’s Feet.” J Clin Aesthet Dermatol. 2023;16(2):37–43. PMID 36909866. pubmed.ncbi.nlm.nih.gov/36909866.
8. Wyrzykowski D, Wieczorek R, Kloska A, et al. “Influence of the modification of the cosmetic peptide Argireline on the affinity toward copper(II) ions.” J Pept Sci. 2024;30(3):e3547. PMID 37752675. pubmed.ncbi.nlm.nih.gov/37752675. (Confirms the sequence Ac-EEMQRR-NH₂ and the Cu(II) affinity.)
9. Errante F, Menicatti M, Pallecchi M, et al. “Susceptibility of cosmeceutical peptides to proteases activity: Development of dermal stability test by LC-MS/MS analysis.” J Pharm Biomed Anal. 2021;194:113775. PMID 33281001. pubmed.ncbi.nlm.nih.gov/33281001.
10. Zhu M, He X, Zhu Z, et al. “The effect of a serum containing acetyl hexapeptide-8, dipeptide diaminobutyroyl benzylamide diacetate and gluconolactone on skin biomarkers, wrinkles and skin texture: Ex vivo and clinical studies.” Int J Cosmet Sci. 2026 (online ahead of print). PMID 41668671. pubmed.ncbi.nlm.nih.gov/41668671. (All authors employed by L’Oréal; five-active formula.)
11. National Center for Biotechnology Information. “PubChem Compound Summary for CID 71587772, Acetyl hexapeptide-3.” pubchem.ncbi.nlm.nih.gov/compound/71587772 (CAS number; deposited structure contains the bond error described above).