In this article
Peptides for hair growth are not one ingredient or treatment. Hair serums can contain biotinoyl tripeptide-1 or acetyl tetrapeptide-3, while copper-peptide experiments use separately identified compounds.[1][2] Match the ingredient and study setting before comparing claims.
Sources checked October 24, 2026. This guide compares product labels and selected original studies. It does not rank treatments, diagnose hair loss or recommend a dose or application schedule.
Which peptides appear in hair products and research?
The Ordinary's US Multi-Peptide Serum for Hair Density ingredient list names biotinoyl tripeptide-1 and acetyl tetrapeptide-3 alongside caffeine and plant extracts.[1] The manufacturer describes a water-based, leave-in serum.[1] This is a finished mixture, not a test of either peptide alone.
The manufacturer says its formulas can change and the website list can differ from the box by purchase date and region.[1] Record the ingredient list on the specific package rather than identifying a product only by the words "multi-peptide".
| Ingredient or preparation | Where it was identified | What to keep separate |
|---|---|---|
| Biotinoyl tripeptide-1 and acetyl tetrapeptide-3 | The Ordinary scalp-serum label.[1] | Two named ingredients in a multi-ingredient product. |
| AHK-Cu | Pyo's isolated-follicle and cell experiments.[2] | Human tissue outside the body, not treated patients. |
| Acetyl tetrapeptide-2 combination | Turlier's hair lotion with creatine and B vitamins.[4] | A different peptide and finished formula. |
| GHK-Cu microemulsion | Liu's delivery-system and mouse experiments.[5] | A laboratory formulation, not a retail-serum trial. |
What did the AHK-Cu copper-peptide study measure?
Pyo and colleagues' 2007 study examined AHK-Cu, identified as alanyl-histidyl-lysine complexed with copper.[2] It used isolated human hair follicles and cultured dermal papilla cells, rather than participants applying a scalp product.[2]
The authors reported follicle elongation and increased cell proliferation.[2] A reduction in apoptotic cells was not statistically significant.[2] The abstract supplies neither a patient sample nor a clinical follow-up duration; it cannot supply a patient regrowth percentage.[2] Its AHK-Cu identity should not be relabeled GHK-Cu.
What have human studies of peptide mixtures measured?
The human studies below tested combinations.[3][4] Their results belong to those formulas and populations, not to every product containing a peptide.
| Original study | Participants and duration | Comparison |
|---|---|---|
| Lueangarun and Panchaprateep, 2020 | 32 participants with mild to moderate androgenetic alopecia; 24 weeks.[3] | Botanical and acetyl tetrapeptide-3 blend versus 3 percent minoxidil. |
| Turlier and colleagues, 2021 | 100 women with acute telogen effluvium; assessment through week 16.[4] | Peptide-containing lotion plus shampoo versus shampoo alone. |
What did the 32-person botanical-peptide trial report?
Lueangarun and Panchaprateep randomized 32 participants in a triple-blind, 24-week trial.[3] The tested blend contained biochanin A, acetyl tetrapeptide-3 and ginseng extracts.[3] The original abstract reports terminal-hair-count increases of 8.3 percent for the blend and 8.7 percent for the minoxidil group, without a statistically significant between-group difference.[3]
A nonsignificant difference in this small comparison is not proof of equivalence. The design also does not isolate the peptide from the botanical ingredients.[3] The full report was unavailable during this source check; these details come from the authors' abstract, not a reconstructed protocol.[3]
What did the 100-woman hair-lotion trial report?
Turlier and colleagues' open randomized trial assigned 51 women to a lotion containing creatine, acetyl tetrapeptide-2 and B vitamins plus mild shampoo, and 49 to shampoo alone.[4] Its primary endpoint was the change in the anagen-to-telogen ratio between weeks 1 and 16.[4]
The abstract reports increased ratios in both groups at week 16.[4] It reports a between-group difference in telogen hair density at week 8, P=0.0465, but gives no numeric between-group effect for the primary endpoint.[4] The open design, mixed formula and shampoo-only comparator matter when interpreting those results.[4]
What does the GHK-Cu delivery study establish about its model?
Liu and colleagues' 2024 journal article tested a GHK-Cu ionic-liquid microemulsion using porcine skin and depilated mice.[5] The report describes increased local peptide delivery and differences in mouse hair measurements.[5] These are formulation and animal observations, not patient scalp-regrowth results.[5]
Its methods specify six mice per group and 21 days of application, while its results discuss a 28-day endpoint and a hair-density figure labels n=10.[5] Those descriptions do not reconcile clearly in the retrieved article.[5] We retain the discrepancy instead of inventing one definitive duration or denominator. No retail product or human injection schedule is established by this experiment.[5]
What should you ask about a peptide hair-growth claim?
Ask for the exact ingredient name, full formula, manufacturer, route and study citation. Ask whether the reported outcome was hair count, shaft thickness, shedding, appearance, cultured-cell growth or delivery through skin. Those are different questions; this page is not a diagnostic checklist.
Request the study population, comparator and follow-up period. Ask whether the research tested the marketed formula or just one ingredient, and who would prescribe and dispense any proposed clinical preparation. Keep unanswered details marked unknown. A seller's explanation is not a substitute for the original report.
Where can you compare related clinical peptide services?
Regenerated.com's September 2026 export of 9,042 US clinic records contains 2,743 listing Peptide Therapy across 49 states plus Washington, DC. Source: Regenerated.com clinic export, September 2026. This is directory category coverage, not market size or a count of confirmed hair-loss or copper-peptide providers.
Browse Peptide Therapy clinics to compare recorded practices. Local examples include Peptide Therapy clinics in Gilbert, Arizona and Peptide Therapy clinics in Phoenix, Arizona. Confirm the exact service with the practice. A listing is not an endorsement or a recommendation to replace a scalp serum with injections.
Frequently asked questions
Does a multi-peptide hair serum necessarily contain copper peptides?
No. The Ordinary's checked US hair-serum list names biotinoyl tripeptide-1 and acetyl tetrapeptide-3, but does not list a copper peptide.[1] Check the specific package rather than assuming from the category name.
Was the AHK-Cu study conducted in patients with hair loss?
No. Pyo's study used isolated human follicles and cultured dermal papilla cells.[2] Human tissue in a laboratory experiment is not a clinical trial in people applying a product.
Did the hair-lotion trial isolate acetyl tetrapeptide-2?
No. Turlier's trial tested a lotion containing creatine, acetyl tetrapeptide-2 and B vitamins, alongside shampoo.[4] It did not test the peptide alone.
Does a Peptide Therapy listing confirm hair-treatment availability?
No. The directory records a broad service category. Ask the practice about the specific preparation, clinician and dispensing source; the listing does not confirm those details.
Sources
- The Ordinary: Multi-Peptide Serum for Hair Density, US product label. Checked October 24, 2026.
- Pyo et al. (2007): tripeptide-copper and human hair follicles in vitro. Checked October 24, 2026.
- Lueangarun and Panchaprateep (2020): peptide and botanical blend trial. Checked October 24, 2026.
- Turlier et al. (2021): randomized hair-lotion study in acute telogen effluvium. Checked October 24, 2026.
- Liu et al. (2024): ionic liquid microemulsion delivery of GHK-Cu. Checked October 24, 2026.