GHK-Cu results timeline: what skin, hair and wound studies measured

GHK-Cu’s most promising results, in wound and skin studies, took weeks to months, not days. In rats, a GHK-Cu gel shrank ischemic wounds by 64.5% in 13 days, against 28.2% untreated (Canapp 2003, Animal). In people, forehead-line scores improved 16.75% by day 56 with a cream combining GHK-Cu and a ferment extract (Wang 2026, Human, single group, n=30), and a scalp spray of copper-free GHK plus 5-aminolevulinic acid beat placebo only at 6 months. GHK-Cu is not an FDA-approved drug for any use (no match on Drugs@FDA, searched 2026-10-30), and the strongest human evidence is a few small trials, several unpublished or company-linked.

Item	Status
US FDA status	No approved GHK-Cu drug for any use (Drugs@FDA, searched 2026-10-30)
Compounding (503A)	Injectable GHK-Cu: withdrawn from Category 2 by its nominators (FDA, 04/22/2026). Non-injectable GHK-Cu: back in Category 1, under evaluation, not on the 503A bulks list (FDA list, May 14, 2026). Next step: FDA advisory committee review before the end of February 2027, date not set
WADA	2026 List: GHK-Cu not named (WADA 2026 List); USADA lists plain GHK (non-palmitoylated tripeptide-1) in cosmetics as not prohibited, with no GHK-Cu ruling (USADA). 2027 List (in force 2027-01-01): GHK-Cu still not named, but S0 now names “peptides” among non-approved substances (WADA 2027 List); no GHK-Cu ruling yet
Strongest evidence	Human RCT, small and mixed (13 to 86 participants); animal wound studies
Human trials	1 registered, not yet recruiting: NCT07706361 (blood GHK-Cu levels with a patch); none completed (ClinicalTrials.gov, searched 2026-10-30)
Last checked	2026-10-30 (status sources re-verified 2026-10-30)

GHK-Cu results timeline at a glance

GHK-Cu is a copper complex of glycyl-histidyl-lysine, a three-amino-acid peptide that occurs naturally in human plasma, saliva and urine and declines with age, according to a review by authors from Skin Biology, a GHK-Cu company (Pickart 2015). The table lists every time point the studies in this guide actually measured, earliest first, with its evidence level. Different studies used different products, so these are cross-study figures, not one continuous curve.

Time point	What was measured	Evidence level
Day 13	Rat ischemic wounds 64.5% smaller vs 28.2% untreated (Canapp 2003)	Animal
Day 14	Under-eye line volume lower, then rose slightly (Wang 2026)	Human, single group (n=30)
Days 14–30	Rabbit wounds filled by day 14 vs 25; healed by day 29.8 vs 34.6 (Gul 2008)	Animal
Day 28	Forehead and cheek line scores down 5.91% and 5.94% (Wang 2026)	Human, single group (n=30)
1 month	Hair count: no significant difference from placebo (Lee 2016, copper-free GHK)	Human RCT (n=45)
8 weeks	Wrinkle volume down vs control serum (Pickart 2018 review)	Human RCT, reported in a review
12 weeks	Facial and eye-area creams; eyebrow hair count (Mateescu 2026)	Small human studies, reported in reviews
12 weeks	After laser resurfacing: no objective difference (Miller 2006)	Human RCT (n=13)
3 months	Hair count: still no significant difference (Lee 2016)	Human RCT (n=45)
6 months	Hair count higher than placebo (Lee 2016)	Human RCT (n=45)

Skin benefits: what studies measured at 2, 4, 8 and 12 weeks

Weeks 2 to 8. The most detailed week-by-week data come from a 2026 study of a face cream that combined GHK-Cu with a bacterial ferment extract (Wang 2026, Human, single group). It enrolled 32 adults with sensitive skin, 30 of whom finished, and measured them at days 14, 28 and 56. Dermatologist scores for forehead lines fell 5.91% by day 28 and 16.75% by day 56; cheek wrinkles fell 5.94% and 8.68%. Redness (erythema index) was 9.94% lower at day 56. The pattern was not a straight line: under-eye line volume dropped at day 14 and then rose slightly, nasolabial line volume improved at day 28 but returned by day 56, and dermatologists saw no change in under-eye or nasolabial lines. There was no vehicle-only group, and the cream had two active ingredients, so the share owed to GHK-Cu is unknown.

Week 8. A randomized, double-blind trial of GHK-Cu in a nano-lipid carrier, described in a 2018 review, reported 55.8% less wrinkle volume and 32.8% less wrinkle depth than the carrier alone after 8 weeks, and 31.6% less wrinkle volume than the cosmetic peptide Matrixyl 3000 (Pickart and Margolina 2018, Human RCT as reported in a review). The review does not give the number of participants.

Week 12. Most cosmetic studies stopped at 12 weeks. A 2015 review by the company-linked group describes a facial cream tested on 71 women with photoaging, an eye cream tested on 41 women that beat both placebo and a vitamin K cream, and a third cream tested on 67 women aged 50 to 59, each over 12 weeks, with reported gains in firmness, fine lines and skin density (Pickart 2015, Human, reported in a review). An independent 2026 evidence review calls the 71-woman study “a conference-level cosmetic report rather than a fully reported controlled trial” and concludes that “the clinical evidence remains sparse” (Mateescu 2026).

Collagen in biopsies. A thigh-skin study found more collagen in 70% of women using GHK-Cu, against 50% with a vitamin C cream and 40% with retinoic acid (Human, reported in a review). The 2015 review dates that result at one month of use; the 2018 review describes the same 70/50/40 result at 12 weeks, so the time point itself is uncertain.

A negative 12-week result. The only randomized GHK-Cu skin-appearance trial indexed on PubMed (searched 2026-10-30) is small and negative on its objective measures. After laser resurfacing around the mouth, 13 patients who completed the study improved by 12 weeks whether or not their skin-care regimen contained GHK-Cu; redness did not clear faster, though patients using GHK-Cu rated their skin quality higher (P = .04) (Miller 2006, Human RCT, n=13). More detail on topical and injected forms is in our GHK-Cu serum vs injection vs retinol comparison.

Hair: what studies measured at 1, 3 and 6 months

The only placebo-controlled hair trial involving the GHK peptide found on PubMed (searched 2026-10-30) did not use GHK-Cu. It tested ALAVAX, a scalp spray combining copper-free GHK with 5-aminolevulinic acid, in 45 men with male pattern hair loss for 6 months (Lee 2016, Human RCT, n=45). Its visits show why the hair timeline is long. At 1 month, hair counts had risen by 10.5 and 11.3 in the active groups and fallen by 3.6 on placebo, a gap that was not statistically significant. At 3 months the placebo group had gained 24.9 hairs, so the difference again was not significant. Only at 6 months did the comparison with placebo reach significance (change ratio 2.38 vs 1.21), with counts up 52.6 and 71.5 in the two active groups against 9.6 on placebo. Hair length and thickness did not differ between groups, and no adverse events were reported.

For GHK-Cu itself, a 2026 review describes a randomized, double-blind, vehicle-controlled split-face study in 18 healthy people in which a GHK-Cu serum improved eyebrow hair count and diameter over 12 weeks, without serious adverse effects (Mateescu 2026, Human RCT, n=18, reported in a review). The reviewers note it addressed thin eyebrows, not scalp hair loss. A 2025 case series of 7 men measured scalp regrowth after five monthly sessions of a tattooing technique that delivered minoxidil, dutasteride and copper peptides together, with no control arm, so the copper peptide’s part cannot be separated (Kuceki 2025, Human case series, n=7).

Earlier work is preclinical. A copper-binding peptide enlarged hair follicles on the backs of fuzzy rats, an effect the authors called similar to topical minoxidil (Uno 1993, Animal), and a related copper tripeptide, AHK-Cu, lengthened human hair follicles in a dish (Pyo 2007, Lab). How GHK-Cu compares with the approved hair-loss drug is covered in GHK-Cu vs minoxidil for hair, and other options are ranked in best peptides for hair loss.

Wounds: days in animals, mixed results in people

Wound studies run on a scale of days. In 24 rats with ischemic wounds, a GHK-Cu gel shrank wounds faster than no treatment on days 3 to 5, 6 to 9 and 11 to 13; by day 13, wound area had fallen 64.5% with GHK-Cu, 45.6% with the gel base alone and 28.2% untreated (Canapp 2003, Animal). In 18 rabbits, treated wounds were smaller than untreated ones at days 7, 14 and 21 (Cangul 2006, Animal). In another rabbit study, wounds filled with new tissue by day 14 instead of day 25 and healed in 29.8 days instead of 34.6, although the first granulation tissue appeared no sooner (Gul 2008, Animal). Mouse burns treated with GHK-Cu in liposomes healed by day 14 after injury (Wang 2017, Animal), and in dogs, wound pads injected with the complex held more type I collagen at day 14 (Swaim 1996, Animal). Not every model responded: in irradiated rat skin flaps, 10 days of GHK-Cu gel made no difference to tissue loss or blood vessels (Parker 2013, Animal).

The two human wound trials point in opposite directions. In diabetic foot ulcers, a GHK-Cu gel reached 98.5% median closure of plantar ulcers against 60.8% on vehicle, closed them about three times faster and cut infections from 34% to 7% (Mulder 1994, Human RCT); the abstract does not give the number of patients or the trial length. In 86 patients with venous leg ulcers, a copper tripeptide cream did no better than placebo, while silver sulfadiazine did (Bishop 1992, Human RCT, n=86).

Why GHK-Cu timelines are uncertain

• Getting through the skin: in lab tests on human skin, almost no peptide or copper crossed intact skin in 9 hours (Li 2015, Lab), so results depend heavily on the formulation.
• Few independent trials: a 2025 review found “a surprising absence of clinical studies” of GHK-Cu in anti-wrinkle products (Mortazavi 2025), and a 2026 review counted about 35% of the primary GHK-Cu literature from 2005 to 2026 as co-authored by researchers from one GHK-Cu company, Skin Biology (Najafi 2026).
• Mixed products: several studies above paired GHK-Cu with other actives, so their timelines describe the product, not the peptide. An independent 2026 review of aesthetic peptides found many trials “limited by small samples, short follow-up, industry sponsorship, or multi-ingredient formulations” (Yi 2026). The newest registered study follows the same pattern: GHK-Cu is one of five peptides in a skin serum tested alongside drugs taken by mouth or injection, with biological-age markers measured at 4 weeks; it is enrolling by invitation and has no results (NCT07888595).
• Lab signals are fast, people are slow: GHK-Cu raised collagen production in cultured fibroblasts (Maquart 1988, Lab), but visible change in people was measured over weeks to months.

Safety and regulatory status

In the human studies above, reported side effects were few: the hair spray trial reported no adverse events, and the eyebrow study reported none serious. In keratinocyte tests, GHK-Cu did not raise skin-irritation markers, unlike copper chloride and copper acetate (Li 2016, Lab). These are small, short studies, so rare or long-term effects are unknown.

Injectable GHK-Cu is a different question. FDA states that “compounded injectable drugs containing GHK-Cu may pose risk for immunogenicity due to the potential for aggregation and peptide-related impurities” and that “there are limited data in humans” (FDA Category 2 page). FDA now lists the injectable form among substances withdrawn from Category 2 by their nominators, and its list updated May 14, 2026 puts the non-injectable form back in Category 1, pending an advisory committee review before the end of February 2027 (FDA 503A categories; FDA PCAC). Advisory committees make non-binding recommendations. Background on that process is in what the FDA compounding vote changes.

Whether a GHK-Cu product counts as a cosmetic or a drug depends on its intended use: cosmetics do not need FDA approval before sale, and FDA treats a claim that a product will “restore hair growth” or “regenerate cells” as a drug claim (FDA, cosmetic or drug). For athletes, USADA says topical peptides are treated the same as injected ones under the WADA List and lists plain GHK as not prohibited, but GHK-Cu itself is not named (USADA). The S0 class covers substances not approved by any government regulator (USADA, S0), and USADA’s cosmetics guidance advises checking Global DRO for any ingredient. USADA’s summary of the 2027 List, in force from January 1, 2027, says S0 now names “peptides” in general and does not list GHK-Cu among its examples (USADA, 2027 List), so athletes need a ruling from their anti-doping organization for GHK-Cu specifically.

Anyone who suspects a side effect from GHK-Cu or any other drug or product can report it to the FDA through MedWatch.