Tetrapeptide-21_
A topical peptide for firmer, plumper skin.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Tetrapeptide-21?
Plain language first. The technical label stays, but it never stands alone.Overview
Tetrapeptide-21 is a cosmetic peptide that boosts skin's production of collagen and hyaluronic acid. In plain terms: used topically, it helps skin look firmer and plumper.
What it's used for
A topical peptide that tells skin to make more collagen and moisture for firmer, plumper skin.
How does Tetrapeptide-21 work?
What it does in the body, and where.Tetrapeptide-21 is a four-amino-acid cosmetic peptide aimed at both collagen and hyaluronic acid.
- 01It signals production of collagen and hyaluronic acidFirmness from one, water retention and plumpness from the other.
- 02Concentrations come from formulation practiceThere is no dose-ranging trial behind the percentages used; they are what manufacturers have settled on.
Where this compound is thought to act.
What else is it used for?
Each use below 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.
- Firmer, plumper skin, applied to the skinOTC / supplement
- Boosting collagen and hyaluronic acidEarly research
How much, and do you cycle it?
The range, and whether you take breaks.Serum, per product, daily. Not cycledCommunity practice
Used daily as part of a routine. The effect depends on continued use and returns to baseline when you stop, so there is nothing to cycle off.
How do I dose and price it?
Enter your vial and your dose. Pick a mix. We show the draw and the cost.The vial holds a fixed amount of drug. Adding more water does not make more drug, it just spreads it thinner, so you draw a bigger number on the syringe for the same dose.
Tetrapeptide-21 is not injected
It is taken on the skin (topical). Applied as a topical product at the concentration the manufacturer sets. There is no injected dose.
How do you store it?
Before mixing, and after.Room temperature, out of light. Cap it tight after each use.
Tetrapeptide-21 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
- A known allergy to this ingredient or to others in the same product
- Broken, cracked, or actively irritated skin
- Anyone who wants established safety data, because none exists for this compound in humans
Stop and get help
- A rash that spreads beyond where you applied it
- Swelling of the face, lips, or eyelids, or any trouble breathing
- Burning that does not settle after rinsing it off
- Anything unusual, since there is no known safety profile to compare it against
Common effects
- Very safe on the skin.
- Beyond the above, unknown. There is no reliable human data on what this compound commonly causes
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Tetrapeptide-21 approved?
And where the numbers on this page come from.Yes. Sold over the counter.
No prescription required, but evidence quality varies by product and country.
- DoseFrom product labeling and published use.
- Vial sizeFrom what vendors typically list; not a recommendation.
- Reviewed22 July 2026
What else is like Tetrapeptide-21?
Others in Skin and cosmetic, side by side.If you're weighing Tetrapeptide-21, it's worth reading GHK-Cu, Melanotan I (Afamelanotide), and Argireline (Acetyl Hexapeptide-8) in the same class.
A topical peptide for firmer, plumper skin.
- Dose
- Serum, per product
- How often
- Daily
A copper skincare peptide for smoother, firmer, younger-looking skin.
- Dose
- Topical serum, 1-2 pumps
- How often
- Daily
The safer, approved tanning peptide for a slow, protective tan.
- Dose
- 0.5 up to 1 mg per day (loading phase)
- How often
- Daily then weekly
A topical Botox-like peptide that softens fine lines, needle-free.
- Dose
- Serum, per product
- How often
- Daily
10What these words mean
Show glossary +
What these words mean
- Titrate
- Starting at a low dose and increasing it slowly over time so your body adjusts and side effects stay mild.
- Subcutaneous
- An injection just under the skin, into the fat layer, usually with a short, thin insulin needle.
- Intramuscular (IM)
- An injection into a muscle, using a longer needle.
- Reconstitution
- Mixing a powdered peptide with liquid (bacteriostatic water) so it can be drawn into a syringe.
- Bacteriostatic water
- Sterile water with a tiny amount of preservative, used to mix powdered peptides.
- Concentration
- How strong the mixed peptide is, in milligrams per milliliter (mg/mL). More water makes it weaker; less water makes it stronger.
- Units (on the syringe)
- The marks on an insulin syringe. 100 units equals 1 mL. They measure how much liquid you draw, not the dose in milligrams.
- mcg and mg
- Units of dose. 1 milligram (mg) equals 1,000 micrograms (mcg).
- GLP-1
- A natural gut hormone that lowers appetite and blood sugar. Drugs that copy it, like semaglutide, are used for weight loss.
- Growth hormone secretagogue
- A compound that nudges your body to release more of its own growth hormone, rather than injecting the hormone itself.
- Half-life
- How long a compound stays active in your body. A longer half-life means you inject less often.
- Peptide vs small molecule
- A peptide is a short chain of amino acids. A few items here (like MK-677 or methylene blue) are small molecules, not true peptides, but people use them the same way.
- Research only
- No approved dose or use in people. Sold for research and not reviewed by the FDA for safety or quality.
- Investigational
- Still being tested in clinical trials and not yet approved or legally sold for general use.
- Banned in drug-tested sport
- Prohibited by the World Anti-Doping Agency (WADA); using it can disqualify a competing athlete.
Last reviewed 22 July 2026