GHK-Cu Dosage Chart: Injection, Topical and Microneedling Doses

This GHK-Cu dosage chart keeps three things apart that most dosing pages blend into one number: subcutaneous injection, topical serum or cream, and microneedling. Each route has a different evidence base, and a milligram figure for one of them says nothing about the others. Below you get the published numbers, what Reddit users say they inject, and the syringe math. None of it is a prescription, because GHK-Cu has no approved human dose.

For what the peptide is and how the overall evidence stacks up, see our GHK-Cu peptide guide. This page is the dose-focused companion.

GHK-Cu dosage chart by route

"The GHK-Cu dose" is three separate questions. Injection has the most Reddit chatter and the least human data. Topical use has the most human data and the vaguest numbers. Microneedling has almost none of either.

Read the status column first. GHK-Cu is a naturally occurring copper-binding tripeptide, and a 2015 review in a peer-reviewed journal describes cosmetic uses and wound-healing work across animals (PMID 26236730). A 2026 evidence-mapping review that searched through 12 August 2026 concluded that the clinical evidence "remains sparse" and that GHK-Cu should be regarded as promising but unproven rather than a validated drug (PMID 42797253). Neither gives a dose shown to work when injected under the skin.

The US regulatory picture is also unsettled. The FDA's page on bulk drug substances nominated for compounding lists injectable GHK-Cu in Category 2, with a note about possible immune reactions from aggregation and impurities and limited human safety data. In February 2026 HHS announced plans to move about 14 restricted peptides, GHK-Cu among them, back to Category 1, but an August 2026 trade-press summary did not confirm the change took effect. I could not verify the current category, so treat it as unresolved. Even Category 1 would only permit compounding, not approval.

What published studies and labels used

There is no prescribing label, so there is no label dose. The published numbers are of four kinds.

Injected animal work. A 2026 aged-mouse study gave GHK-Cu at 15 mg/kg, either by intraperitoneal injection for 5 days or intranasally for 8 weeks. The intranasal group improved on a spatial learning task in both sexes, while the injected group showed a transient improvement in males only. Scaling a mouse dose to a person by body surface area (a factor of roughly 3 against 37) would put 15 mg/kg near 1.2 mg/kg, or about 85 mg for a 70 kg adult. That is my calculation, not a figure from the paper, and it is more than forty times the 2 mg that Reddit users inject. The mismatch is the point: nobody derived the 1 to 3 mg convention from an experiment.

Human topical work. The reviews describe small cosmetic-cream studies, and a 2025 review of topical GHK as an anti-wrinkle ingredient noted a surprising absence of clinical studies of GHK-Cu itself (PMID 39963574). Vendor charts list anything from about 0.1% to 4% with no source I could verify, and our overview lists 0.1% to 1%. No trial has established a best topical percentage.

Human procedure-adjacent work. The 2026 evidence map describes a 13-participant study after CO2 laser that was negative on objective endpoints, and an 18-participant split-face eyebrow study that reported positive cosmetic hair outcomes without defining what form of GHK-Cu was applied.

Microneedle delivery. A 2026 systematic review of 64 records found that microneedle delivery raises GHK-Cu skin uptake in lab and pig-skin models, but that no adequately powered registered human randomized trial exists for microneedle or dermaroller-assisted GHK-Cu (PMID 42787770).

What Reddit users report taking

To see what people actually do, I read 223 posts and comments from 25 threads across 11 subreddits, mostly r/Peptidesource, r/Biohacking, r/PeptidePathways and r/BiohackingU, dated August 2025 to October 2026. After removing bot notices, deleted comments, questions, jokes, planned doses and advice that was not about the writer's own use, 31 comments from 7 subreddits stated a personal injected GHK-Cu amount. This is a self-selected sample of people who chose to post, and none of it is verified.

Here is how the 31 distribute.

The mode was 2 mg a day, usually 7 days a week. One poster calculated the 2 mg draw as 12 units from a 50 mg vial in 3 mL, which matches the math below. A smaller group used 1 mg or less, including a 5-on, 2-off schedule at 1 mg and one person on 100 mcg every other day on a doctor's advice. Five reported 2.5 to 3 mg, and five reported 3.3 mg or more, up to 5 mg a day for a year or longer. One commenter wrote that "most people" use 2 mg, which fits the count and shows how a convention spreads.

The upper end deserves caution. One r/PeptidePathways commenter (Apr 2026) wrote "There’s no reason to spend that long titrating. I went straight to 3mg a day with zero issues." (link). One person's lack of problems is not a safety result, and the same thread contains someone who started at 1 mg for two weeks to assess tolerance. In r/BiohackingU (Oct 2026) a commenter replied to a user asking about going from 3 mg to 4 mg that "3-4 mg ghk-cu dosing isn’t well established and serum copper doesn’t tell you much about its safety" (link).

Reconstitution math: mg, mL and syringe units

The most useful thing Reddit threads show is how often the arithmetic goes wrong. One poster wrote that they were taking 10 mg a day, drew a dozen alarmed replies, and then clarified that they meant 10 units. A person with a 100 mg vial asked whether 1 mL of water would work and was told the usual figure is 3 mL for every 50 mg. Another correctly guessed that 2 mg from a 100 mg vial mixed to 10 mL is 20 units.

The formula is: units on a U-100 syringe = dose in mg ÷ concentration in mg/mL × 100. A worked example: a 100 mg vial reconstituted with 3 mL of bacteriostatic water is 33.3 mg/mL. A 2 mg dose is 2 ÷ 33.3 = 0.06 mL, which is 6 units, since 100 units equals 1 mL. One r/Biohacking poster with exactly this setup reported 6 units for 2 mg, so the arithmetic matches practice.

Vial size sets how long a vial lasts: a 100 mg vial gives 50 doses at 2 mg or 100 at 1 mg, while a 50 mg vial gives 25 or 50. Water volume is a convenience choice. Less water means a tiny draw that is hard to measure, and more means a larger draw of a weaker solution, which commenters said stings less. Reddit comments mention 2 mL, 3 mL, 5 mL, 6 mL and 10 mL, and some people move the solution to a larger empty sterile vial to fit it. I would not improvise that; it adds a contamination step, so ask a pharmacist.

If the 5 mg or 100 mg figure on a label is wrong, every calculation above is wrong with it. One commenter claimed that many 100 mg vials hold 130 to 150 mg, which I could not verify and which is why a batch certificate matters. If you want a supplier to check against, Ascension Peptides sells GHK-Cu 100 mg in a 10 mL vial at $69.00 as of 2026-10-11 ($0.69 per mg). Kovera Labs tests every batch (HPLC, LC-MS identity, net content, endotoxin, sterility and heavy metals), more than 98 percent of tested batches pass, and batch certificates are public. Prices are in US dollars, shipping is US only and all sales are final. New customers can use code PEPTIDEDECK for 50 percent off. Our guide to where to buy GHK-Cu explains how to read a certificate.

Timing, frequency and cycle length

No study has tested a schedule, so this section reports habits. Among the Reddit dose reports, most described a single daily morning or evening injection. Three used 5 days on and 2 off, one injected three days a week, and one every other day. Cycle length varied: one commenter ran 6 weeks on and 2 to 3 weeks off, two ran 8 weeks then a break, and four said they had used it continuously for a year or more, one for three years. The sample cannot tell you which works better.

The cycling argument is live. In one r/BiohackingU thread three commenters said flatly that GHK-Cu does not need to be cycled, one warned that constantly raising the dose could wear out receptor sensitivity, and a r/Biohacking commenter likened 5-days-on cycling to scratching a scab. None cited evidence. One practical wrinkle: blend vials such as KLOW and GLOW also contain BPC-157, TB-500 or KPV, so cycling advice for a blend may not apply to GHK-Cu alone.

On time to effect, the Reddit comments agree that skin comes first and hair later, if at all. One said some people see results at 6 to 8 weeks. Another wrote that improvements begin toward the end of the first month, with the best results at 3 to 6 months. Two commenters at 6 and 8 weeks described skin that looked thicker, one adding that thinning hair had changed little. These are unblinded impressions, some from people using other products at the same time.

Topical serum and microneedling doses

Reddit is nearly silent here. Only two people in the whole file described topical use, both in the same thread: one made a GHK-Cu serum for scalp microneedling and was also using minoxidil, biotin and red light, so nothing can be attributed to the peptide; the other described a hyaluronic-acid serum with 2.5% of a different copper peptide, AHK-Cu, applied before stamp-style microneedling. That second figure is not a GHK-Cu percentage and should not be read as one.

What can be said is limited. A finished cosmetic serum is made to cosmetic microbial standards. A lyophilized research vial is not, and pushing a homemade solution through micro-channels in the skin is a different risk from rubbing on a finished product. Because the 2026 review found the delivery question unanswered in people, any percentage for a microneedling serum is a guess. A dermatologist can say what is sterile and what needle depth is appropriate.

What changes the dose

These variables come up in the sources, though none can be quantified.

Copper intake. GHK-Cu is roughly 16 percent copper by mass (my calculation from the molecular weights). A 2 mg dose then carries about 0.3 mg of copper, which is about a third of the 0.9 mg adult daily recommended intake, and 5 mg carries about 0.8 mg. The 10 mg a day upper limit that one commenter cited is a real figure for adults from all sources. This arithmetic assumes a pure product with the labeled mass, so it is a rough guide only.

Zinc. Many users take it alongside GHK-Cu, though other commenters called it unnecessary at injected doses and warned that high-dose zinc can cause copper deficiency, which is documented.

Body weight. The animal work is per kilogram; community charts are flat. A 28-year-old who weighs 43 kg asked on r/BodyHackGuide whether 2 mg every other day was enough and got no dose-based answer in the data. Whether body size matters is untested.

Injection tolerance. This is the real driver of practical dose changes. Eleven commenters described stinging, burning, redness or a bump, and three said they had none. People reported adding water to the vial (3 mL for 50 mg, 6 mL or more for 100 mg), drawing 6 to 25 extra units of bacteriostatic water into the syringe, using a half-inch needle, splitting an injection across sites, and in one case using an antihistamine ointment afterwards. One r/Peptidesource commenter (Dec 2025) wrote "I'm doing a lower dose and adding a ton of BAC. It still burns bad." (link). One poster reported flushing and nausea at 1 mg after switching vendors, which is a reminder that product quality changes everything. Spreading redness, hives or fever after an injection is a reason to stop and see a clinician. Our GHK-Cu side effects page covers what is documented.

Vial storage. The 28-day rule for opened vials is a hospital convention. A 100 mg vial at 1 to 2 mg a day lasts 50 to 100 days, and commenters said they used theirs well past a month, one claiming 70 days. I found no GHK-Cu stability data, so that is anecdote.

For what each goal (skin, hair, recovery) is based on, see our GHK-Cu for skin and hair page.

Frequently Asked Questions

What is the GHK-Cu dosage?

There is no approved or trial-established GHK-Cu dose. Reddit users who stated a personal injected amount most often reported 2 mg a day (15 of 31 comments), with a range from 0.1 mg to 5 mg or more. Animal studies dose per kilogram, and topical products list percentages instead of milligrams.

How many units is 2 mg of GHK-Cu?

It depends on the water you added. With a 100 mg vial and 3 mL, 2 mg is 6 units on a U-100 syringe. With 5 mL it is 10 units, and with 10 mL it is 20 units. For a 50 mg vial, 2 mL gives 8 units and 3 mL gives 12 units.

What is the GHK-Cu dose for microneedling?

No human trial has established one. A 2026 systematic review found no adequately powered registered human randomized trial of microneedle-delivered GHK-Cu. Percentages in vendor charts are conventions, and a homemade solution is not made to cosmetic sterility standards.

How long do people run GHK-Cu?

Reddit comments describe cycles of 6 to 8 weeks followed by a break, and at least four people said they used it continuously for a year or longer. No study defines a cycle in humans, so these are habits, not evidence.

Is injectable GHK-Cu legal and FDA-approved?

It is not FDA-approved for any use. It is sold as a research chemical, and the FDA has listed injectable GHK-Cu among bulk substances of concern for compounding. Reclassification was announced in 2026, but I could not verify that it took effect, so ask a clinician rather than assuming.

Checking a vial before you do any math

Ascension Peptides lists the 100 mg, 10 mL vial at $69.00 as of 2026-10-11, with per-batch Kovera Labs testing and public batch certificates; US shipping only and all sales are final. Treat every Reddit number here as an anecdote.