GHK-Cu Dosage and Protocol: Topical Strengths, Injectable Studies

Key takeaways

• Every GHK-Cu dose tested on its own in people is topical: a 0.1 percent wound gel (about 0.5 g once daily for 14 days, in a trial still recruiting), a 0.4 percent cream that did no better than placebo on venous ulcers, a 2 percent eyebrow serum used twice daily for 12 weeks, and facial creams of unreported strength used once or twice daily for 12 weeks.
• Retail serums list copper tripeptide-1 at roughly 0.5 to 3 percent, often without stating it. No study compares concentrations, so stronger is not proven better.
• There is no human dose for injected GHK-Cu because no human study has tested it on its own; the only needle studies that included a copper peptide mixed it with other actives and had no control group. The 1 to 2 mg daily and 2 to 5 mg several-times-a-week charts online are seller conventions.
• The part of those charts that can be checked is the copper: GHK-Cu is about 16 percent copper, so a 2 mg injection carries about 0.3 mg past the gut, and eight weeks of the popular schedule adds up to roughly 6 to 13 mg.
• Use topical GHK-Cu once or twice daily, apart from strong acids and high-dose vitamin C, after a patch test, and judge it at 12 weeks for skin or six months for hair. No US pharmacy may compound the injectable as of October 2026.

GHK peptide dosing has a short honest answer: the only GHK-Cu doses studied on their own in people are topical, at 0.1 to 2 percent applied once or twice a day for 2 to 12 weeks, and there is no human dose for injections because no human study has tested injected GHK-Cu on its own. This page lists the studied strengths, translates retail percentages into milligrams, and shows the copper arithmetic behind the injection charts sold online. For hair, our best peptides for hair growth guide ranks the evidence and copper peptides for hair loss compares serums with injections; the GHK-Cu profile has the full evidence and legal status, and GHK-Cu injection versus topical compares the two routes.

Topical GHK-Cu: the doses that were studied

Sources: (NCT07437586), (Bishop 1992), (Bo 2026), (Lee 2016); the facial-cream studies were never published in full and are described in GHK-Cu results by week. A diabetic foot ulcer trial used a metered daily gel without a reported strength, and a small study of scalp tattooing used 1.2 percent copper peptides mixed with two hair-loss drugs; the GHK-Cu profile and copper peptides for hair loss cover them.

Two things stand out. The range is narrow, 0.1 to 2 percent, and no study compared strengths, so there is no dose-response curve for any outcome. And the best-specified dose in the whole literature is the recruiting wound trial's: about half a gram of a 0.1 percent gel, which is roughly 0.5 mg of GHK-Cu applied to an open wound once a day (NCT07437586).

Retail strengths, and what a percentage means

Retail serums in October 2026 typically list copper tripeptide-1 at about 0.5 to 3 percent, with 1 percent common, and many do not state a figure at all. Assuming the usual weight-for-weight percentage and a copper share of about 16 percent, the arithmetic is:

These are amounts applied to the skin, not amounts absorbed, and they are not comparable to the injection figures below.

How much gets through the skin

Less than the label suggests, and the laboratory data disagree on how much. When a 0.68 percent GHK-Cu solution was left on excised human skin for 48 hours under infinite-dose conditions, about 136 micrograms of copper per square centimeter crossed split-thickness skin and about 97 stayed behind as a depot (Hostynek 2011). In a second laboratory, almost no peptide or copper crossed intact human skin in 9 hours; after pretreatment with a microneedle array, 134 nanomoles of peptide and 705 nanomoles of copper got through (Li 2015). Neither resembles a thin layer of serum worn for a day, and no study has measured GHK-Cu or copper in the blood of anyone using a topical product. For a cosmetic, that is acceptable: the studies measured changes in the skin the product touched, which needs no systemic exposure.

Injected GHK-Cu: no study of its own, so no human dose

A dose is a finding from a study, and injected GHK-Cu has never been studied on its own: no trial for skin, hair, healing or anything else, no pharmacokinetic measurement, no safety data. The closest are two uncontrolled hair series that put a copper peptide into the scalp as part of a mixture, one by intradermal injection with four growth factors and thymosin beta-4, the other by tattoo machine with minoxidil and dutasteride; neither can isolate an effect or a dose, and neither used the under-the-skin injections the charts describe (copper peptides for hair loss covers both). The independent 2026 evidence map of every GHK-Cu study it could find lists only topical human work, calls GHK-Cu promising but unproven, and sets out what an injectable product would need first, including sterility, endotoxin, loose-copper limits and route-specific safety thresholds (Mateescu 2026). None of that exists. Injectable GHK-Cu also cannot be compounded by any US pharmacy as of October 2026; it awaits an advisory committee review due by February 2027, as the legal tracker explains.

The injection charts that circulate, and their copper

For scale: the body keeps copper in range mainly by limiting absorption in the gut and excreting the surplus in bile, and human balance studies find net copper loss at dietary intakes below about 0.8 mg a day and net gain above about 2.4 mg a day (Bost 2016). Those figures describe copper that passed through the gut's controls; an injection skips them, so oral intake limits cannot be converted into injection limits. None of this proves that 0.3 mg under the skin is harmful. It shows that nobody has checked. We do not give a reconstitution example for a product that no pharmacy may legally prepare and no study has dosed.

How often, how long, and what not to mix

• Frequency. Once or twice daily, as studied; nothing supports more.
• Duration. Judge skin at 12 weeks, when the cosmetic studies measured their results (GHK-Cu results by week); judge scalp hair at six months at the earliest (copper peptides for hair loss).
• Mixing. Formulators keep copper peptides away from strong acids and high-dose vitamin C in the same step, because low pH and ascorbate can strip or react with the copper; use them at different times of day. Patch test before the face or scalp.
• Who should ask a clinician first. Anyone with Wilson disease or another copper disorder, chronic liver disease, a copper or metal allergy, or a pregnancy; the profile explains why.

Bottom line

The GHK-Cu dosage with evidence is a topical one: 0.1 to 2 percent, once or twice a day, for 2 to 12 weeks, with no study showing that a higher strength works better. The injectable dosage does not exist, because the injectable has never been studied on its own in people; the charts online are guesses whose only checkable feature is the copper they deliver past the gut. Use the serum the way it was studied and judge it at the end of the study period. Leave the vials alone.

Frequently asked questions

+−What is the GHK-Cu dosage?

For topical use, the strengths with human data run from a 0.1 percent wound gel (about half a gram once daily in a trial still recruiting) to a 2 percent eyebrow serum applied twice daily for 12 weeks, with facial creams of unreported strength used once or twice daily for 12 weeks. For injection there is no dosage, because no human study has tested injected GHK-Cu on its own. The milligram charts online are seller conventions, not studied doses.

+−How often should you take GHK peptide?

As a topical, once or twice a day is what the studies used: twice daily in the eyebrow study and several facial-cream studies, once daily in the registered wound trial. No study compares frequencies, so more often has no data behind it. As an injection, no frequency has been studied; the five-days-a-week and two-to-three-times-a-week schedules online were never tested in people.

+−What concentration of GHK-Cu serum is best?

Nobody knows, because no study has compared concentrations. Retail serums list copper tripeptide-1 at roughly 0.5 to 3 percent, with 1 percent common, and many do not state it at all. The only hair study used 2 percent; the wound trials used 0.1 and 0.4 percent. A higher number on the label is a formulation and marketing choice, not a dose-response finding, and stronger products are more likely to irritate.

+−What is the GHK-Cu injection dosage?

There is none in the medical literature. No human study has tested injected GHK-Cu on its own for any purpose, so there is no studied dose, schedule or safety limit; the two small hair series that put a copper peptide into the scalp mixed it with other active ingredients. The figures that circulate, 1 to 2 mg under the skin daily five days a week for 4 to 8 weeks, or 2 to 5 mg two or three times a week, are seller and forum conventions. Injectable GHK-Cu also cannot be compounded by any US pharmacy as of October 2026, so any vial is a research chemical.

+−How much copper is in GHK-Cu?

About 16 percent by weight, because copper (about 63.5 g/mol) is roughly a sixth of the complex (about 402 g/mol). A 2 mg injection therefore carries about 0.3 mg of copper and a 50 mg vial about 8 mg. A 1 percent serum holds about 1.6 mg of copper per gram of product, most of which stays on or in the outer skin. Injected copper skips the gut, which is where the body normally limits how much copper it takes in.

+−What should you not mix copper peptides with?

Formulators usually keep copper peptides away from strong acids and high-dose vitamin C in the same step, because low pH and ascorbate can strip or react with the copper; using them at different times of day is the common workaround. Retinoids are generally used in alternation. There is no documented drug interaction for topical use. For injections the question cannot be answered, because the injections themselves are unstudied.

+−How long should you use GHK-Cu before judging it?

Twelve weeks for skin, because that is when the cosmetic studies measured their results, and at least six months for scalp hair, because hair grows slowly and even minoxidil usually takes 6 to 12 months to show results. Use it as studied, once or twice daily after a patch test, change nothing else in your routine, and take photographs the same way at the start and the end.

+−Can a doctor prescribe GHK-Cu injections?

A prescription does not create a legal source. Injectable GHK-Cu is not an approved drug, and as of October 2026 no US pharmacy may compound it: it came off FDA's Category 2 list in April 2026 only because its nomination was withdrawn and awaits an advisory committee review due by February 2027. A clinic offering GHK-Cu injections is supplying a research vial, whatever its paperwork says.

Sources

1. SourceClinicalTrials.gov NCT07437586. Topical GHK-Cu gel for acute skin wound healing: phase 2, randomized, double-blind, vehicle-controlled split-wound study; 0.1 percent w/w gel, about 0.5 g once daily for 14 days; 60 participants planned; started February 2026, recruiting. (2026)
2. StudyBishop JB et al. A prospective randomized evaluator-blinded trial of two potential wound healing agents for the treatment of venous stasis ulcers. J Vasc Surg 1992;16:251-7. (1992)
3. StudyBo SL, Nararatwanchai T, Supornpun N, Poomarapan K, Thaploka S. The efficacy of 2% copper peptide (GHK-Cu) serum for eyebrow hypotrichosis: a randomized, double-blind, vehicle-controlled, split-face comparative study. Procedia of Multidisciplinary Research 2026;4(5). Conference poster abstract; not indexed in PubMed. (2026)
4. StudyLee WJ et al. Efficacy of a complex of 5-aminolevulinic acid and glycyl-histidyl-lysine peptide on hair growth. Ann Dermatol 2016;28:438-43. (Copper-free GHK conjugate.) (2016)
5. StudyHostynek JJ, Dreher F, Maibach HI. Human skin penetration of a copper tripeptide in vitro as a function of skin layer. Inflamm Res 2011;60:79-86. (2011)
6. StudyLi H et al. Microneedle-mediated delivery of copper peptide through skin. Pharm Res 2015;32:2678-89. (2015)
7. ReviewMateescu DM et al. GHK-Cu as a bioactive metallopeptide and drug-delivery cargo: coordination chemistry, formulation science, therapeutic evidence, and a translational roadmap (systematic evidence-mapping review). Pharmaceutics 2026;18:1077. (2026)
8. ReviewBost M et al. Dietary copper and human health: current evidence and unresolved issues. J Trace Elem Med Biol 2016;35:107-15. (2016)