GHK-Cu with zinc thymulin
Topical GHK-Cu with zinc thymulin scalp serum
Written by Aaron CuhaReviewed Sep 2026
Also known as: Copper peptide scalp serum, GHK-Cu Zn-thymulin, Hair duo serum
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
A scalp serum you drip on and leave. A common mix is 5 mg per mL of copper peptide with 10 micrograms per mL of zinc thymulin. Do that division. The copper peptide outweighs the other one 500 to 1. Neither has a real trial for hair in people.
What people take it for
- Less shedding.
- Thicker looking hair.
- A calmer scalp.
- Something to add on top of minoxidil.
What the trials actually showed
Nobody has tested the mix. The zinc thymulin hair claim comes from one short research letter. Scientists took human scalp hair follicles, kept them alive in a dish, and found thymus peptides changed how they grew. Human tissue, in a dish, not on a head. The copper peptide has human data, but it is about skin, not hair, and it did not go well. Thirteen people used it after laser skin work and blinded raters saw no real change in redness, wrinkles or skin quality. One trial is running now and it is a gel on small wounds in 60 healthy adults. It has not reported. Now the math. A 1 mL squirt gives you 5 mg of copper peptide and 10 micrograms of the thymus peptide. Copper metal is about 16 percent of the copper peptide by weight, so that squirt puts roughly 0.8 mg of copper on your scalp.
What people report
Reports, not trial results
The good
- Less shedding in the first couple of months. This is the main report.
- Scalp feels less irritated.
- Hair looks thicker, usually judged by the person in a mirror.
The bad
- Blue or green stains on pillowcases and light hair.
- Scalp itch or irritation in some people.
- Nothing at all, and disappointment next to minoxidil.
- Hair sheds more in some seasons on its own, so a new serum gets credit or blame it did not earn.
Where these come from: Hair loss forums, clinic write-ups and seller review pages. People talking, in a condition that moves around by itself and where almost nobody changes only one thing.
My bottom line
If the thymus peptide is what you came for, you are buying it at one five hundredth the weight of the ingredient you are mostly paying for. Minoxidil has the trials.
An opinion, not a finding. I am a coach, not a doctor.
Overview
A compounded scalp dropper serum, commonly 5 mg/mL of copper peptide with 10 micrograms/mL of zinc thymulin, so the copper peptide outweighs the thymic peptide 500 to one. Neither component has a published randomised trial for hair growth in people, and the combination has never been tested. The thymulin hair evidence is human follicles in a dish.
Hair loss clinics and compounders sell this as a leave-on scalp serum, typically in a 25 mL dropper bottle. The stated concentrations are usually GHK-Cu 5 mg/mL with zinc thymulin 10 micrograms/mL, and that ratio is the fact this page exists to point at.
At those concentrations the copper peptide is 500 times the thymulin by mass. A 1 mL application delivers 5 mg of GHK-Cu and 10 micrograms of zinc thymulin. Whatever a buyer came for, almost all of what lands on the scalp is copper peptide. Copper is about 16% of the GHK-Cu complex by mass, so that 1 mL application carries roughly 0.8 mg of elemental copper onto skin. Applied topically that number sits in a different context from an injection, since the stratum corneum limits absorption and the gut is not involved either way, but it is the scale worth knowing.
On the evidence. GHK-Cu's human record is entirely topical, which is at least the right route here, and it is not strong: a randomised trial in 13 patients after CO2 laser resurfacing found no significant blinded difference in redness, wrinkles or overall skin quality, with only the patients' own questionnaire favouring it. The one registered GHK-Cu trial is a gel on punch-biopsy wounds in an estimated 60 healthy adults and has not reported. Neither study is about hair.
Zinc thymulin's hair evidence is one research letter. Thymic peptides, including thymulin, were applied to human scalp hair follicles in organ culture and were found to modulate follicle growth differentially between peptides. Human tissue, which is better than mouse, in a dish, which is not a person, in a letter rather than a trial.
So this is a product where both components have plausible mechanistic stories, one has topical human data for a different endpoint, one has ex vivo human tissue data for the right endpoint, and neither has a randomised trial for hair. The pooled peptide literature for skin found the overall topical effect to be modest, and hair has an even thinner file than skin.
Mechanism of action
GHK-Cu delivers copper to tissue and drives collagen and glycosaminoglycan production in culture and in rodent wound models, with claimed effects on follicle size and perifollicular vasculature. Thymulin is a nine amino acid thymic peptide that requires zinc for activity, and its zinc-bound form is the one used in these serums; the hair rationale comes from organ culture work showing thymic peptides modulate human follicle growth. No published work describes the two together, on a scalp or anywhere else.
Human evidence
No randomised trial of either component for hair growth in people, and none of the combination.
- The serum: no published study, no registered trial.
- Zinc thymulin for hair: human scalp follicles in organ culture, reported in a research letter. No human trial.
- GHK-Cu: human data is topical and is about skin, not hair. In 13 patients after laser resurfacing, blinded assessment found no significant difference in redness, wrinkles or skin quality.
- The one registered GHK-Cu trial is a gel on punch-biopsy wounds and has not reported.
What this does not tell you: Organ culture tells you a follicle responded to a molecule in a dish. It does not tell you whether a serum reaches a follicle through intact scalp at a useful concentration, whether the response persists, or whether hair on a head gets thicker.
What it has been measured to do
What people using it report
Uncontrolled and self-selected, so it cannot show that anything works. It is still the best guide on this page to what people actually do with GHK-Cu with zinc thymulin, what they expect, and what goes wrong. The full account, including the negative reports, is below.
Nothing indexed yet
The 5 citations on this page do not report a result for any of the 36 goals indexed here. Registry entries, pharmacokinetics, safety reporting and regulatory records are not outcome evidence, and most of what sits here is one of those.
Reading the research record
Hair loss is a field where uncontrolled reports are close to worthless, for a reason specific to hair: the condition fluctuates, shedding is seasonal, and people who start a new serum almost always start or stop something else at the same time. A product with no trial in a field like that will accumulate glowing reports whether or not it works.
The ratio is the point to carry away. At 5 mg/mL against 10 micrograms/mL, this is a copper peptide serum with a trace of thymic peptide in it, and the thymic peptide is the one with the follicle evidence, thin as that is. If the thymulin is what you came for, you are buying it at one five-hundredth of the mass of the ingredient you are mostly paying for.
The evidence, charted
Fig. 1a · evidence scale
13people, across 1 human study cited here
- 2006 · Archives of Facial Plastic Surgery13100%
The whole total is one study of 13. Counts are the enrollment each human citation on this page states, which includes observational cohorts where nobody was given the compound. 1 further human citation states no participant count and is not counted here. Studies still recruiting are excluded, and only studies cited on this page are counted.
Fig. 1b · evidence mix
2 of 5 citations here are human work, the rest are not.
- Human · given to people240%
- In vitro · cells, tissue or a dish120%
- Review · summarises other work240%
Counted from the citation list on this page, typed as this page types it. It understates any literature larger than the sources we cite, and a review counts once however many studies it covers.
Fig. 2 · evidence over time
Evidence spans 4 distinct years, 2006 to 2026, counted from the citation list on this page.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four jurisdictions shown. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Fig. 5 · molecular identity
- Modality
- Blend
- Molecular weight
- Not on file
- Half-life
- Stated in words, not a number
- Sequence length
- None on file
see the exact wording below
Half-life as stated on file: Not applicable to a serum left on the scalp, and no absorption or clearance study of either component has been published.
No amino acid sequence is on file for GHK-Cu with zinc thymulin, which is expected: a blend is not built from residues.
Fig. 6 · what is in the vial
No mass split can be drawn for this blend
Sellers do not publish a consistent vial size for GHK-Cu with zinc thymulin, so the share of each component is not knowable from the outside. Splitting the bar evenly would invent the number this page exists to question.
- GHK-Cuamount not stated
- Zinc thymulinamount not stated
Component list from the product labels we hold. Amounts are label mass, never a dose.
Key studies & citations
- In vitro2012
Thymic peptides differentially modulate human hair follicle growth
A research letter reporting that thymic peptides, including thymulin, thymosin beta 4 and prothymosin alpha, differentially modulate the growth of human scalp hair follicles in organ culture. Human tissue in a dish, with different peptides producing different effects. It is the origin of the zinc thymulin hair claim and it is not a trial in people.
Journal of Investigative Dermatology - Human2006
Effects of topical copper tripeptide complex on CO2 laser-resurfaced skin
Thirteen patients randomised after circumoral CO2 laser resurfacing to a regimen with or without GHK-Cu skin care. Computer analysis and blinded evaluators found no significant difference in resolution of redness, and objective evaluation found no significant improvement in wrinkles or overall skin quality. Only the patients' own questionnaire favoured GHK-Cu, at P = 0.04.
Archives of Facial Plastic Surgery - Human2026
Topical GHK-Cu Gel for Acute Skin Wound Healing
A recruiting phase 2 trial, estimated 60 healthy adults, two punch-biopsy wounds each, every wound randomised to GHK-Cu gel or matching vehicle. Started February 2026 and has not reported. It is the only registered interventional trial of GHK-Cu and it is a gel on skin.
ClinicalTrials.gov - Review2026
Oral and topical peptides for skin aging: systematic review and meta-analysis of randomized controlled trials
Nineteen randomised trials in 1,341 participants found peptides improved hydration and brightness with a modest pooled wrinkle effect of mean difference 0.27, largely driven by oral polypeptides rather than topicals, and inconsistent effects on elasticity and density. This is the size of the topical peptide effect in skin, where the evidence is considerably better developed than it is in hair.
Frontiers in Medicine - Review2024
Is Copper Still Safe for Us? What Do We Know and What Are the Latest Literature Statements?
Total body copper is 50 to 120 mg, the safe upper limit of average intake is put at 10 to 12 mg a day against a reference limit of 0.9 mg a day, and the biological half-life from diet runs 13 to 33 days. The review notes that even small changes in copper concentration can carry significant toxicity. It covers dietary and environmental copper, not an injected peptide complex.
Current Issues in Molecular Biology
What users report
Self-reported experiences, not evidence. Nothing below was measured under controlled conditions, and reports like these cannot separate a real effect from placebo, from the training or diet change that accompanied it, or from what the product actually contained. They are here because knowing what people describe, including what goes wrong, is worth reading alongside the studies.
- Less shedding within the first two months, the most common single report.
- Scalp feeling less irritated.
- Hair looking thicker, usually assessed by the person themselves in a mirror.
- Blue or green staining on pillowcases and light hair from the copper.
- Nothing at all, and disappointment when compared against minoxidil.
- Scalp irritation or itch in a minority.
Sources: Hair loss forums including the tressless community, clinic write-ups and vendor testimonial pages. Uncontrolled self-reports, in a condition that fluctuates seasonally and where almost nobody changes only one variable.
Frequently asked questions
How much of each is in an application?
At the common 5 mg/mL copper peptide with 10 micrograms/mL zinc thymulin, a 1 mL application delivers 5 mg of GHK-Cu and 10 micrograms of zinc thymulin. The copper peptide outweighs the thymic peptide 500 to one.
Is there a trial for zinc thymulin and hair?
No human trial. The evidence is a research letter reporting that thymic peptides modulate human scalp follicle growth in organ culture, which is human tissue in a dish.
Is the copper a problem on skin?
A 1 mL application carries roughly 0.8 mg of elemental copper, applied to intact skin rather than injected, so absorption is limited in a way it is not with a vial. The staining on pillowcases is the visible reminder of how much copper is in the bottle.
How does it compare to minoxidil?
Minoxidil is an approved topical for androgenetic alopecia with a large randomised evidence base. Neither component of this serum has a randomised trial for hair in people.
Has the combination been tested?
No. There is no study of GHK-Cu with zinc thymulin together, on a scalp or anywhere else.