Acetyl Tetrapeptide-3 and Biotinoyl Tripeptide-1 are each a topical skincare peptide.
| Comparison | Acetyl Tetrapeptide-3 Capixyl · tetrapeptide-3 | Biotinoyl Tripeptide-1 biotinyl-GHK · biotinyl tripeptide-1 |
|---|---|---|
| How it works | How it works This peptide is sold to strengthen how firmly a hair sits in the scalp, rather than to grow new hair directly. | How it works The core of this molecule is GHK, the same tripeptide as the copper peptide, but the attachment is different and so is the use. |
| What it is | A hair peptide sold for thinning, with evidence that mostly belongs to a combination product. | GHK with a biotin tail, sold for hair and lashes rather than skin. |
| Status | Sold over the counterCosmetic ingredient | Sold over the counterCosmetic ingredient |
| Typical dose | — | — |
| How often | Daily | Daily |
| Stays active | Not measured, and not the right question | Not measured, and not the right question |
| Dose comes from | No established range | No established range |
| Cycled? | Not cycled Community practice | Not cycled Community practice |
| What it does | ||
| Drug class | Cosmetic peptide | Cosmetic peptide |
| Used for | A scalp peptide used for thinning hair and weak anchoring, usually as part of a branded blend rather than on its own. | A hair and lash peptide, used for thinning hair, weak lashes and shedding. |
| Receptors hit | — | — |
| Numbers | ||
| Full dose line | Serum or scalp treatment, 0.1 to 5% | Serum, 2 to 6 ppm typical in a finished product |
| Why that cycle | Used daily as part of a routine. The effect depends on continued use and fades when you stop, so there is nothing to cycle off. | Used daily as part of a routine. The effect depends on continued use and fades when you stop, so there is nothing to cycle off. |
| Weight / effect | Not measured in a trial | Not measured in a trial |
| Chain length | 4 residues | 3 residues |
| Common vial | — | — |
| Before you start | ||
| Route | On the skin (topical) | On the skin (topical) |
| Do not use if | Broken or actively inflamed scalp skin A known allergy to any component of the finished product | Broken or actively inflamed scalp skin A known allergy to any component of the finished product |
What separates them
Proof behind the dose. Every dose here comes from community practice. Not one is backed by a published human study, which is worth knowing before you read the numbers as if they were equivalent.
What doesn't differ: They are both taken the same way (on the skin), aimed at the same thing (hair growth) and on the same schedule (daily). Neither has a measured effect size from a published trial, so there is no number to rank them on.
What people actually report
Acetyl Tetrapeptide-3
- Very well tolerated in cosmetic use.
- Occasional scalp irritation, usually from other ingredients in the formula.
- A spreading rash or significant swelling where applied
Biotinoyl Tripeptide-1
- Very well tolerated in cosmetic use.
- Occasional irritation on the eyelid margin from lash products, usually from the formula rather than the peptide.
- Eye irritation that does not settle after stopping a lash product
- A spreading rash where applied
Side effects are what users and trials report most often, not a complete list. Anything sudden, spreading, or breathing-related is an emergency regardless of which compound caused it.
People also compare
This comparison does not cover cost, long-term safety, or how you personally will respond. Effect figures come from separate trials in different populations and are not always directly comparable to each other. Nothing here is medical advice or a recommendation to use any of these. Talk to a clinician about your own situation.