Myristoyl Hexapeptide-16_Dosage, benefits & legal status
Also known as Myr-LKKALK
Sold for lashes, first described as an antimicrobial.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Myristoyl Hexapeptide-16?
Plain language first. The technical label stays, but it never stands alone.Overview
This is one of the two peptides in most lash-growth serums. Three things are worth knowing. Its sequence is printed incorrectly by at least one major supplier, and the wrong version is a fragment of thymosin beta-4, the molecule sold as TB-500 and already covered on this site, so a sequence lookup can hand you the wrong peptide entirely. The composition of what suppliers actually sell varies so much between them that there is no single answer to what is in the bottle. The only published human study of a lash serum containing it tested a formula that also contained four growth factors and the other peptide, so nothing in its results can be attributed to this ingredient.
Myristoyl hexapeptide-16 is a lipopeptide, myristoyl-Leu-Lys-Lys-Ala-Leu-Lys, CAS 959610-54-9, formula C47H91N9O8 and molecular weight 910.3. It appears in eyelash and eyebrow serums, usually alongside myristoyl pentapeptide-17, and supplier sheets attribute keratin-related effects to it with no study attached. No single declared composition exists: four suppliers declare four materially different blends, in two different salt forms. Its primary-literature identity is different again. The patent that first described this class presents these myristoylated polycationic hexapeptides as polymeric biosurfactants with antimicrobial activity, reporting minimum inhibitory concentrations at or below 100 parts per million against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and methicillin-resistant S. aureus.
What it's used for
Cosmetic eyelash and eyebrow serums, nearly always combined with myristoyl pentapeptide-17. It has no medical use and no drug approval.
How does Myristoyl Hexapeptide-16 work?
What it does in the body, and where.Start with the sequence, because the sequence is where this ingredient goes wrong before any question of effect arises.
- 01A datasheet that contradicts itselfOne major reagent supplier's datasheet for this ingredient prints two different sequences in two different fields of the same document. Its three-letter field gives myristoyl-Leu-Lys-Lys-Thr-Glu-Thr, and its own abbreviated field gives myristoyl-Leu-Lys-Lys-Ala-Leu-Lys. Those are not variants of one another. They are different peptides.
- 02Which one is right, settled by arithmeticThe published formula and mass decide it. Myristoyl-LKKALK calculates to C47H91N9O8 at 910.30 daltons, matching the published C47H91N9O8 and 910.3 exactly. Myristoyl-LKKTET calculates to C45H84N8O12 at about 929 daltons, wrong on carbon, hydrogen, nitrogen and oxygen alike. The correct sequence is Myr-LKKALK, and no supplier claim was needed to establish it.
- 03Why the wrong answer is a familiar oneLKKTET is the active motif of thymosin beta-4, the molecule sold as TB-500, already covered on this site. So the erroneous sequence is not random noise: it is a well-known peptide fragment from an entirely different corner of this field that has found its way into a lash-serum datasheet. Anyone checking this ingredient against a database can be handed a TB-500 fragment and not notice.
- 04What the molecule was first described asThe patent literature that characterized this class describes myristoylated polycationic hexapeptides as polymeric biosurfactants with antimicrobial activity, with minimum inhibitory concentrations at or below 100 parts per million against several bacteria including methicillin-resistant Staphylococcus aureus. That makes chemical sense: a fatty tail on a strongly positively charged peptide is the standard architecture of a membrane-disrupting antimicrobial. No cosmetic source mentions this, and the keratin story appears only on supplier sheets.
- 05The evidence question readers actually askThe answer is that neither lash peptide has ever been tested by itself in people. The one published human study of a serum containing them was open-label, single-arm, uncontrolled and unblinded, with 30 enrolled and 29 completing, funded by an industry educational grant, and the formula tested contained four growth factors and sage oil alongside both peptides. Its reported gains in thickness and curl cannot be attributed to either peptide, or to the peptides at all rather than the growth factors.
A schematic of the compound's mechanism, not a diagnostic image.
What else is it used for?
Each group carries its own evidence level.Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
The sequence conflict, and how it resolves
none- No dataA major supplier's single datasheet prints two contradictory sequences: Myr-LKKTET in one field and Myr-LKKALK in another.
- lab-analysisFormula arithmetic settles it. Myr-LKKALK gives C47H91N9O8 at 910.30 daltons, matching the published values. Myr-LKKTET gives C45H84N8O12 at about 929 daltons and cannot be the molecule.
- No dataLKKTET is the active motif of thymosin beta-4, sold as TB-500 and already covered on this site. The incorrect sequence is a fragment of a completely different compound.
There is no single thing being sold
none- No dataFour suppliers declare four materially different compositions, ranging from the near-neat peptide to blends with acetic acid and water, with water and glycerin, or inside a four-peptide mixture, and in two salt forms.
- No dataOne supplier's sheet for this peptide omits the preservative system that its companion sheet for the related pentapeptide discloses.
Neither lash peptide has been tested alone
none- Human observationThe only published human study used a formula containing four growth factors and both peptides, and was open-label, single-arm, uncontrolled and unblinded with 29 completers.
- No dataSupplier sheets cap each peptide at 5 percent specifically when combined, so combination is the commercial default and single-ingredient data does not exist.
- Lab studyThe patent that characterized this class describes it as an antimicrobial biosurfactant, with minimum inhibitory concentrations at or below 100 parts per million against several bacteria including MRSA. No cosmetic source mentions this.
The sequence is the trap. A major supplier's datasheet prints Myr-LKKTET in one field and Myr-LKKALK in another, and the published formula and mass show that only LKKALK can be right. The wrong version matters more than an ordinary typo because LKKTET is the thymosin beta-4 motif of TB-500, a compound with its own page here, so a careless lookup swaps one field's peptide for another's entirely. Second, the lash claims. Neither this peptide nor myristoyl pentapeptide-17 has been tested on its own in people, and the one published study used a formula containing four growth factors and sage oil alongside both peptides, with no control group and no blinding, so its thickness and curl figures belong to the formula rather than to any ingredient. Third, there is no single declared composition for this ingredient: four suppliers declare four different blends in two salt forms. Last, its first scientific description was as an antimicrobial biosurfactant, and no cosmetic source mentions it.
The published record
0
Papers and trials about Myristoyl Hexapeptide-16
Searched: myristoyl hexapeptide-16.
Left out: LKKTET (the thymosin beta-4 active motif, which is TB-500 and has its own slug. A major supplier datasheet wrongly prints this as the sequence for this ingredient, so searching it would import TB-500 literature onto a lash-serum page. The most important rejection on this row); myristoyl pentapeptide-17 (has its own slug; the two are nearly always sold together and no study separates them); thymosin beta-4 (same problem as LKKTET, and it has its own slug); eyelash growth (a descriptor dominated by bimatoprost, a prostaglandin drug unrelated to any peptide); biosurfactant (a large industrial chemistry literature).
Europe PMC was searched on 30 October 2026 for these terms and returned nothing.
Counted from Europe PMC indexing, not read by a person.
At a glance
Four things to know about Myristoyl Hexapeptide-16
Evidence
Cosmetic
Category
Skin and cosmetic
Common vial
Varies
Half-life
Not applicable
How much, and do you cycle it?
The range, and whether you take breaks.Set by the finished product, as directed by the product. Not applicable No range
An ingredient in a finished cosmetic, used as the product directs. No cycling scheme applies.
Not applicableNo figure
No half-life has been published, and a circulating half-life would not be the useful measure for a topical cosmetic ingredient.
You can compare this against the whole library to see where it sits.
How is it given?
Dosing context and source notes.Supplied as a ready-made solution, so there is nothing to mix.
How do you store it?
Before mixing, and after.Room temperature, out of light. Cap it tight after each use.
Myristoyl Hexapeptide-16 ships as a cream, gel, or serum. Keep it at room temperature away from sun and heat unless the label says otherwise. Refrigerating an emulsion can split the texture. Watch for color, smell, or separation changes and stop using it if any appear.
What are the side effects and cautions?
Known cautions and warnings for this compound.Solubility, computed: 83% charged residues, 50% hydrophobic. Water usually sufficient.
A first-pass rule from peptide manufacturers' guidance. It does not account for disulfide bridges, salt form or how the powder was dried, and it predicts what should be easy rather than what will happen in your vial.
Who should avoid it
- Any expectation of an effect from this peptide specifically: it has never been tested alone in people
- Using a sequence lookup without checking it, since a major supplier's own datasheet prints two contradictory sequences for this ingredient
Stop and get help
- Eye irritation, redness or swelling after application near the lash line
- Signs of an allergic skin reaction
Common effects
- Nothing established for this peptide alone in a published human study
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Myristoyl Hexapeptide-16 approved?
And where the numbers on this page come from.Not as a medicine. Myristoyl Hexapeptide-16 is sold without a prescription as a cosmetic ingredient, which is a different thing from being approved as a drug.
- Approval statusCosmeticSold without a prescription as an ingredient in cosmetics, such as skincare and hair products. The FDA does not approve cosmetics before they are sold, and being easy to buy says nothing about whether it works.
- RouteOn the skin (topical)
- Checked30 October 2026
- DoseNo dose has been established in people.
- Vial sizeFrom what vendors typically list; not a recommendation.
- Sources
What has happened recently
A cosmetic ingredient, not a drug. The INCI name is MYRISTOYL HEXAPEPTIDE-16 and the CAS number is 959610-54-9. There is no single declared composition to report, and that absence is itself the finding: one supplier declares the peptide with acetic acid and water, another sells it essentially neat, a third sells it inside a four-peptide blend, and a fourth declares it with water and glycerin at 1,000 parts per million. Two salt forms are in circulation. For a reader trying to work out what they are buying, the INCI name alone does not settle it. Note also the relationship to the ingredient already on this site: myristoyl pentapeptide-17 is the usual partner, and supplier sheets cap each of the two at 5 percent specifically when they are used together, so combination is the commercial norm rather than an option.
You can compare this against the whole library, or read how to check a seller.
What else is like Myristoyl Hexapeptide-16?
Others in Skin and cosmetic, side by side.If you're weighing Myristoyl Hexapeptide-16, it's worth reading Myristoyl Pentapeptide-17, Octapeptide-45, and Oligopeptide-1 (EGF) in the same class.
Sold for lashes, first described as an antimicrobial.
- Dose
- Set by the finished product
- How often
- As directed by the product
The lash-serum peptide, used where people want to avoid prostaglandins.
- Dose
- Serum, per product
- How often
- Daily
A cosmetic peptide whose patent says more than its label.
- Dose
- Set by the finished product
- How often
- As directed by the product
Epidermal growth factor under a cosmetic name, and the only real protein on this shelf.
- Dose
- Serum, per product
- How often
- Daily
Guides for this compound
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
- How to Read a Peptide COA
What the purity number does and does not tell you, and how to spot an edited report.
- How to Vet a Peptide Vendor
Independent COAs, HPLC purity, and the red flags that mean walk away.
Sources
- Sachdev and colleagues, Journal of Clinical and Aesthetic Dermatology, the lash serum study(2020)Volume 13, issue 2, pages 61 to 66. The only published human study of a serum containing this peptide, and the reason the combination question matters. Open-label, single-arm, unblinded and uncontrolled, 30 participants enrolled and 29 completing, funded by an educational grant from an industry sponsor. The formula tested contained four growth factors, namely KGF, FGF, IGF-2 and VEGF, plus sage oil, plus both myristoyl hexapeptide-16 and myristoyl pentapeptide-17. Reported outcomes included increases in lash thickness and curl. Because the formula contained seven active components, none of the result can be attributed to this peptide or to the peptides as a group. No DOI exists for this paper; a Crossref title search returns nothing.