Acetyl Tetrapeptide-2 (Thymulen 4)_Dosage, benefits & legal status
Also known as Thymulen 4, Thymulen 4 BG, Uplevity, Peptigravity, Ac-KDVY, Ac-Lys-Asp-Val-Tyr-OH
A four-residue piece of the thymus hormone thymopoietin, close kin to thymopentin, sold by two suppliers with two different stories. Its only independent study was done in cultured skin cells.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Acetyl Tetrapeptide-2 (Thymulen 4)?
Plain language first. The technical label stays, but it never stands alone.Overview
It is a firming and anti-aging ingredient listed in hundreds of serums, creams and hair lotions, so many people already put it on their skin. The best human figures come from Lubrizol: after 56 days of a cream with 2% Uplevity, skin deformation fell 25.2% and elasticity rose 16%, but the panel size and the placebo results were not published. The only independent study used skin cells in a dish, and despite the thymus-hormone branding, no study shows it acts on the skin's immune system in people.
Acetyl tetrapeptide-2 is Ac-Lys-Asp-Val-Tyr-OH, residues 33 to 36 of the thymus hormone thymopoietin with an acetyl cap: thymopentin without its first arginine. Lucas Meyer Cosmetics, now part of Clariant, sells it as Thymulen 4, a thymopoietin mimic for skin regeneration and immune defense, while Lipotec, now part of Lubrizol, sells the same INCI ingredient as Uplevity, an anti-sagging peptide said to raise fibulin-5 and LOXL1. Neither supplier's claims have independent human data; the one independent study found stiffer keratinocytes in culture.
What it's used for
A cosmetic ingredient in firming and anti-aging serums and creams and in some hair-loss lotions, listed in about 535 products. Used only on the skin.
How does Acetyl Tetrapeptide-2 (Thymulen 4) work?
What it does in the body, and where.Acetyl tetrapeptide-2 is a short piece of thymopoietin, a thymus hormone, sold by two suppliers with two different accounts of what it does.
- 01A thymopentin fragmentThymopentin, on this site, is Arg-Lys-Asp-Val-Tyr, positions 32 to 36 of thymopoietin. Acetyl tetrapeptide-2 drops the first arginine and caps the lysine with an acetyl group, leaving positions 33 to 36. Neither supplier says which fragment it used, and no receptor or binding target has been identified.
- 02Two supplier storiesLucas Meyer says skin and the thymus share many hormonal signals and that thymus hormones fall with age, and pitches Thymulen 4 as a thymopoietin mimic for skin regeneration and immune defense; it has published no data. Lubrizol says Uplevity raises fibulin-5 and LOXL1, two proteins needed to assemble elastic fibers, up to 2.3-fold and 1.7-fold against placebo in lab tests, and switches on cell-anchoring genes and induces several collagens and elastin, without numbers (supplier data).
- 03What independent work showsThe only independent study exposed cultured keratinocytes for 48 hours and found the cells grew stiffer, most at 0.5 mcg/mL, though no statistical test against untreated cells was reported and the differences between concentrations were not significant. Whether the peptide reaches live skin cells from a cream has not been tested.
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.
Independent lab study
Early research- Lab studyIn HaCaT keratinocytes exposed for 48 hours to 0.5, 5 or 50 mcg/mL, the peptide made cells stiffer, most at 0.5 mcg/mL, but no statistical test against untreated cells was reported and the differences between concentrations were not significant (one-way ANOVA p > 0.05).
- Lab studyCOL17A1, a gene for a protein that anchors outer skin cells, rose significantly at 0.5 mcg/mL.
- No dataThe paper is internally inconsistent: the Results report that COL17A1 rose at 0.5 mcg/mL, while the Discussion and Conclusions say ACTN1, COL17A1 and ITGB4 fell, and a Results passage and a figure caption mislabel the peptides. Stiffness is shown only relative to control, with no values in the text. The peptide came from Lipotec, and the paper does not mention thymopoietin.
Hair lotion trial (combination product)
Early research- Human trial100 women aged 19 to 50 with acute telogen effluvium, 51 using a lotion of creatine, acetyl tetrapeptide-2 and B vitamins three evenings a week plus a mild shampoo and 49 controls using the shampoo alone, for 16 weeks at 2 centers.
- Human trialTelogen hair density fell significantly at all time points with the lotion, and the difference from control was significant at week 8 (P = 0.0465); total hairs shed fell more at week 8 (P = 0.0392).
- No dataOpen-label, with no placebo lotion, and run by Pierre Fabre employees; the abstract reports no between-group result for the registered primary outcome, the anagen to telogen ratio at week 16, and the peptide's share of the effect cannot be separated out.
Lubrizol's Uplevity data
Supplement or cosmetic- Lab studyIn lab tests, fibulin-5 and LOXL1 expression rose up to 2.3-fold and 1.7-fold against placebo (supplier data quoted by the reseller Lotioncrafter).
- Human trialWomen aged 40 to 60 with sagging facial skin used a 2% Uplevity cream twice daily for 56 days: maximal deformation fell 25.2%, elasticity rose 16% and face contour fell 0.13 cm; in self-assessment, 95% felt more toned skin and 90% felt it had a firming effect.
- No dataPanel size, placebo results, blinding and statistics were not published (a reseller says the test used a placebo), and Lubrizol's claim that skin looks almost 9 years younger comes with no method.
Lucas Meyer's Thymulen 4 claims
none- No dataClariant describes Thymulen 4 as a biomimetic of thymopoietin that boosts skin regeneration and reinforces cutaneous immune defenses.
- No dataA 2015 trade article says the supplier ran one lab test and one clinical test, with no design, panel size or results public.
- No dataNo study shows that a tetrapeptide applied to the skin acts on the skin's immune system in people.
It is often described as part of the Thymulen 4 ingredient family; Thymulen 4 is the trade name of Lucas Meyer's product, and the family was Thymulen 4 and Thymulen 2. What usually goes unmentioned is that Lubrizol sells the same INCI ingredient as Uplevity with different claims. Its uses are often listed as skin firmness, epidermal renewal and age-related changes in skin structure, but these come from two suppliers: firmness and structure are Lubrizol's Uplevity claims, while Lucas Meyer claims skin regeneration and immune defense and does not use the word firmness for Thymulen 4. It is correctly said to differ from thymulin and other thymic peptides, but it is a near copy of thymopentin: KDVY is thymopentin (RKDVY) without its first arginine, plus an acetyl cap.
The published record
Papers and trials about Acetyl Tetrapeptide-2 (Thymulen 4)
1 papers tagged human · 1 not reviews or lab · 1 clinical trial publications
Furthest stage reached: Published trials only, 1 clinical trial publication, no phased trial registered
Counted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count.
At a glance
Four things to know about Acetyl Tetrapeptide-2 (Thymulen 4)
Evidence
Cosmetic
Category
Skin and cosmetic
Common vial
Varies
Half-life
Not established
How much, and do you cycle it?
The range, and whether you take breaks.2% Uplevity solution in a cream or serum (supplier), about 10 ppm peptide if the solution is 0.05% peptide, twice daily (supplier test). Daily use Community practice
Applied daily like other cosmetic actives. The supplier's firming test used it twice a day for 56 days, and the hair-lotion trial applied it three evenings a week for 16 weeks.
Not establishedNo figure
Applied to the skin. No skin-penetration, absorption, stability or blood-level data have been published.
You can compare this against the whole library to see where it sits.
What does it cost?
Typical dose and cost, in plain numbers.Acetyl Tetrapeptide-2 (Thymulen 4) is not injected
It is taken on the skin (cream or serum). A leave-on cosmetic ingredient in creams, serums and hair lotions. Lubrizol recommends 1 to 2% of Uplevity solution in a finished product (2% in its firming test and at a reseller), and its specification lists acetyl tetrapeptide-2 at 0.05%. If that is the peptide content of the solution, 1 to 2% Uplevity gives about 5 to 10 ppm (0.0005 to 0.001%) of the peptide; Lubrizol does not say what the 0.05% refers to. Lucas Meyer's Thymulen 4 was listed at 5 to 10% in 2015, but its peptide content is not published, so its peptide level cannot be worked out. There is no oral or injected dose.
How do you store it?
Before mixing, and after.Room temperature, out of light. Cap it tight after each use.
Acetyl Tetrapeptide-2 (Thymulen 4) 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.Who should avoid it
- Not studied on its own in people: the only human data come from a supplier test in women aged 40 to 60 and a hair-lotion trial in women aged 19 to 50 in which it was one of several ingredients
- Not studied by injection or by mouth: it is made and sold only as a skin-care ingredient
- Known sensitivity to a product that contains it
Stop and get help
- Redness, burning, itching or a rash where it is applied
Common effects
- No study has reported side effects of the isolated peptide in people
- In a 16-week randomized trial in 100 women, 51 used a hair lotion that combined it with creatine and B vitamins, and overall tolerance was rated excellent; the trial was open-label and was not a sensitization study
- In cultured skin cells it was not toxic across 0.05 to 50 mcg/mL over 48 hours (Kobiela 2018)
- No repeated patch test, sensitization or irritation study has been published, and no Cosmetic Ingredient Review safety assessment was found
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Acetyl Tetrapeptide-2 (Thymulen 4) approved?
And where the numbers on this page come from.Not as a medicine. Acetyl Tetrapeptide-2 (Thymulen 4) 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 (cream or serum)
- Checked19 October 2026
- DoseFrom the concentration range manufacturers formulate at. This is a product strength, not a dose set by a regulator or a trial.
- Vial sizeFrom what vendors typically list; not a recommendation.
- SourcesFDA GSRS substance record, acetyl tetrapeptide-2 (UNII M24S4WZS8J)SpecialChem, acetyl tetrapeptide-2 INCI pageClariant, Thymulen 4 BG product pageSpecialChem, Thymulen 4 BG datasheet (Lucas Meyer Cosmetics)CosmeticOBS, A peptide mimicking the youth hormone (January 28, 2015)Clariant completes acquisition of Lucas Meyer CosmeticsGCI Magazine, Lipotec's Uplevity peptide (July 17, 2015)Lotioncrafter, Uplevity Solution (reseller)Lubrizol, Uplevity peptide solution technical data on KnowdeLubrizol, Uplevity peptide solutionKobiela T et al., International Journal of Peptide Research and Therapeutics 2018;24:577-587Turlier V et al., Journal of the European Academy of Dermatology and Venereology 2021;35 Suppl 2:12-20DailyMed, search for UNII M24S4WZS8JSkinsort, acetyl tetrapeptide-2
What has happened recently
A cosmetic ingredient, not a drug, with no designations of any kind. Listed in the EU cosmetic ingredient database (CosIng, reference 54140) with the single function skin conditioning; the databases that mirror it list no restriction. FDA's substance registry gives it UNII M24S4WZS8J, and it appears as an inactive ingredient in 6 labels on DailyMed: four SPF 25 products (two tinted sunscreens, a BB cream and a tinted moisturizer) and two hair-growth serum or foam products. Both suppliers state China compliance (supplier data). No Cosmetic Ingredient Review safety assessment was found. Lucas Meyer Cosmetics sells it as Thymulen 4; the ingredient came from IEB (European Institute of Cell Biology, founded 1993), the forerunner of Lucas Meyer Cosmetics, at one point a business unit of the Unipex Group. IFF owned Lucas Meyer before Clariant completed its purchase in April 2024, at an enterprise value of USD 810 million. Lipotec (Gavà, Spain) sells the same INCI ingredient as Uplevity; trade press reported a new firming test of it in July 2015, and Lubrizol has owned Lipotec since 2012. FDA's registry also lists the brand name Peptigravity; who sells it is not established. Research-grade material is sold as a lab reagent.
You can compare this against the whole library, or read how to check a seller.
What else is like Acetyl Tetrapeptide-2 (Thymulen 4)?
Others in Skin and cosmetic, side by side.If you're weighing Acetyl Tetrapeptide-2 (Thymulen 4), it's worth reading Acetyl Tetrapeptide-3, Acetyl Tetrapeptide-5 (Eyeseryl), and Biotinoyl Tripeptide-1 in the same class.
A four-residue piece of the thymus hormone thymopoietin, close kin to thymopentin, sold by two suppliers with two different stories. Its only independent study was done in cultured skin cells.
- Dose
- 2% Uplevity solution in a cream or serum (supplier), about 10 ppm peptide if the solution is 0.05% peptide
- How often
- Twice daily (supplier test)
A hair peptide sold for thinning, with evidence that mostly belongs to a combination product.
- Dose
- Serum or scalp treatment, 0.1 to 5%
- How often
- Daily
A topical peptide aimed at under-eye puffiness rather than lines.
- Dose
- Serum, per product
- How often
- Daily
GHK with a biotin tail, sold for hair and lashes rather than skin.
- Dose
- Serum, 2 to 6 ppm typical in a finished 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
- FDA GSRS substance record, acetyl tetrapeptide-2 (UNII M24S4WZS8J)(2026)Ac-Lys-Asp-Val-Tyr-OH with defined stereochemistry; C26H39N5O9, MW 565.617; CAS 757942-88-4; brand names Thymulen 4 and Peptigravity.
- SpecialChem, acetyl tetrapeptide-2 INCI page(2021)CosIng reference 54140, function skin conditioning; trade products Thymulen 4 BG (Lucas Meyer), Uplevity (Lubrizol) and a blend.
- Clariant, Thymulen 4 BG product page(2026)Water, butylene glycol, dextran and acetyl tetrapeptide-2; described as a biomimetic of thymopoietin that boosts skin regeneration and reinforces cutaneous immune defenses, with no data shown.
- SpecialChem, Thymulen 4 BG datasheet (Lucas Meyer Cosmetics)(2023)Last updated April 18, 2023; the same supplier claims; lists pH 0.0, an apparent data error.
- CosmeticOBS, A peptide mimicking the youth hormone (January 28, 2015)(2015)Thymulen 4 came from IEB, the forerunner of Lucas Meyer Cosmetics; use level 5 to 10%; one lab and one clinical test mentioned, with no results.
- Clariant completes acquisition of Lucas Meyer Cosmetics(2024)Bought from IFF at an enterprise value of USD 810 million; completed in April 2024.
- GCI Magazine, Lipotec's Uplevity peptide (July 17, 2015)(2015)Women aged 40 to 60 with sagging facial skin, 2% Uplevity cream twice daily for 56 days: maximal deformation down 25.2%, elasticity up 16%, face contour down 0.13 cm. No panel size or placebo arm given.
- Lotioncrafter, Uplevity Solution (reseller)(2026)Fibulin-5 up to 2.3-fold and LOXL1 1.7-fold against placebo in lab tests (supplier data); 2% use level; aqua, acetyl tetrapeptide-2 and caprylyl glycol.
- Lubrizol, Uplevity peptide solution technical data on Knowde(2026)Acetyl tetrapeptide-2 specification 0.05%; use level 1 to 2%; listed as CFDA compliant; skin-age claim of almost 9 years.
- Lubrizol, Uplevity peptide solution(2026)Claims the dermal layer looks 9 years younger, with no method or panel size; suitable for hand care.
- Kobiela T et al., International Journal of Peptide Research and Therapeutics 2018;24:577-587(2018)The only independent study: Warsaw University of Technology with a cosmetics maker, peptide from Lipotec. In HaCaT keratinocytes for 48 hours it increased cell stiffness, most at 0.5 mcg/mL, with no significant differences between concentrations; not toxic. Does not mention thymopoietin.
- Turlier V et al., Journal of the European Academy of Dermatology and Venereology 2021;35 Suppl 2:12-20(2021)Pierre Fabre trial (NCT04652232), open and randomized, 100 women with acute telogen effluvium for 16 weeks; a lotion of creatine, acetyl tetrapeptide-2 and B vitamins beat shampoo alone on telogen hair density at week 8 (P = 0.0465); no between-group result is reported for the week-16 primary outcome; tolerance excellent.
- DailyMed, search for UNII M24S4WZS8J(2026)Listed as an inactive ingredient in 6 labels: four SPF 25 tinted products and two hair-growth products.
- Skinsort, acetyl tetrapeptide-2(2026)Found in 535 products; describes it as an anti-aging peptide said to boost the skin's immune defenses and renew its outer layers, repeating Lucas Meyer's claims.
Beyond these, 2 records are indexed. Browse the records