TB-500 + GHK-Cu Stack: Evidence, Mechanisms, and Protocol

What TB-500 actually is

TB-500 is a synthetic seven-amino-acid fragment of thymosin beta-4: residues 17 to 23, N-acetylated (Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln), molecular weight about 889 g/mol [1]. It is not the full 43-amino-acid thymosin beta-4 protein and not thymosin alpha-1 [1]. The full protein is found in blood, saliva, tears and wound fluid, and the nomination FDA reviewed describes the LKKTETQ stretch as the actin-binding site behind its proposed wound-healing effects [1].

That distinction matters when reading the literature. Full-length recombinant thymosin beta-4 has been tested in people: a phase 1 study enrolled 54 healthy volunteers in single-dose cohorts and 30 in multiple-dose cohorts, with participants receiving full-length thymosin beta-4 or placebo [11], dry-eye trials used 0.1% eye drops [12], and a placebo-controlled trial enrolled 96 patients after a heart attack [13]. None of those studies tested TB-500 [1].

What GHK-Cu actually is

GHK is a tripeptide (glycyl-L-histidyl-L-lysine) found in human plasma, saliva and urine, with levels reported to decline with age, and it is proposed to work as a copper complex [6]. The actions usually attached to it come from laboratory and animal work summarized by the researchers who proposed them: GHK is reported to stimulate collagen and proteoglycan production, modulate metalloproteinases and their inhibitors, attract immune and endothelial cells to an injury, and speed wound healing in dogs, rats, mice and pigs [6]. These are preclinical or proposed mechanisms, not demonstrated human effects [6].

Is there any evidence for the combination?

Any case for combining them rests on proposed mechanisms related to tissue repair, not on results from testing the two together.

TB-500's own laboratory picture is thin. FDA found no in-vivo animal study of TB-500 for wound healing, and in an in-vitro scratch-wound test TB-500 at 50 micrograms/mL did not induce wound closure in fibroblast cultures; a shorter metabolite (N-acetylated LKKTE) did show activity [1].

Where the human evidence stands

TB-500: no published human study. FDA searched PubMed, Embase, ClinicalTrials.gov and other sources and found no article in which TB-500 was given to a human; none of the three papers the nominator cited involved TB-500 in people [1]. Its adverse-event database search through March 26, 2025 retrieved no TB-500 reports, and its food and supplement complaint system (January 1, 2004 to March 10, 2025) retrieved two cases about a blended TB-500 and BPC-157 product, with no safety assessment [1]. FDA found no published case reports [1].

GHK-Cu: small topical trials, mixed results. A randomized trial in 13 patients whose skin had been resurfaced with a CO2 laser found no significant difference in redness resolution, wrinkles or overall skin quality on computer analysis and blinded evaluation; a patient questionnaire did show a significant difference in overall skin quality favoring GHK-Cu (P=.04) [7]. A randomized, evaluator-blinded trial in 86 evaluable patients with venous stasis ulcers found a 0.4% tripeptide copper complex cream no different from an inert vehicle for ulcer size, while silver sulfadiazine 1% did reduce ulcer size [4].

Another wound type gave a positive result. A multicenter, randomized, evaluator-blinded, placebo-controlled trial tested a glycyl-L-histidyl-lysine copper complex gel on diabetic neuropathic plantar ulcers, with every patient also on a standardized wound-care protocol that included sharp debridement and pressure-relieving footwear. Median area closure was 98.5% with the copper peptide gel versus 60.8% with vehicle (p < 0.05), and closure was three times faster. In plantar ulcers treated immediately after debridement, ulcer infections were less frequent (7% versus 34%, p < 0.05) [5].

The 2026 systematic review retained 64 records and concluded that, despite four decades of preclinical work, the human literature on GHK-Cu is thin and fragmented: most randomized trials are small and use facial cosmetic creams, and microneedle delivery has not been tested in a single registered, adequately powered human randomized trial [8].

Is there a protocol to follow?

No. TB-500 has no approved dose and no human dosing study; the nomination FDA reviewed proposed a 3 mg/mL lyophilized powder for subcutaneous or intramuscular injection, which is a proposed product description, not a dose that has been tested in people [1]. GHK-Cu has no FDA-approved dose or product either: topical cosmetic strengths are set by manufacturers and are not FDA-reviewed, and the controlled wound trials tested a 0.4% tripeptide copper complex cream in venous ulcers and a copper peptide gel in diabetic plantar ulcers, neither of them injectable [4][5].

Injection changes the regulatory picture. An injectable GHK-Cu product is not a cosmetic and is not FDA-approved [14], and FDA's concern for both injectable peptides is immunogenicity, an immune reaction, potentially amplified by peptide aggregation and impurities [1][15].

Regulatory status

TB-500: FDA's July 2026 review found no USP or National Formulary monograph, no FDA-approved drug containing it, and no approved product in Canada, Australia, the UK, Belgium, Ireland, France, Norway, Germany, Spain or Italy, or authorized by the European Medicines Agency [1]. It sits in the nominated-but-withdrawn table of FDA's page on bulk substances that may raise significant safety risks when compounded [15], and in none of the three categories on FDA's list of bulk substances for state-licensed pharmacies and physicians (updated May 14, 2026) [2]. The Pharmacy Compounding Advisory Committee voted on July 23, 2026 in favor of adding TB-500 to the bulks list, against FDA staff's recommendation; that advice is non-binding and listing would take formal rulemaking [16][1]. HHS's draft enforcement-discretion policy, filed October 28, 2026, names TB-500 acetate for subcutaneous or intramuscular injection among six peptides, says HHS does not intend to take enforcement action against pharmacies and physicians that meet its conditions, and states that it creates no rights and is not binding [17][18].

GHK-Cu: no FDA-approved drug contains it [2]. Topical copper peptide serums are sold as cosmetics without FDA approval, and a topical product claiming to treat disease or change the body's structure or function would legally be a drug [14]. Non-injectable GHK-Cu is in category 1 of FDA's list for state-licensed pharmacies and physicians, the group under evaluation, for which FDA generally does not intend to act against compounders if the conditions in its guidance are met [2][19]. Injectable GHK-Cu is in the nominated-but-withdrawn table, where FDA states that compounded injectable drugs containing GHK-Cu may pose a risk for immunogenicity and that there are limited data in humans to inform safety considerations [15]. FDA has said it intends to consult the Pharmacy Compounding Advisory Committee before the end of February 2027 about whether to include GHK-Cu on the bulks list; no vote has happened [2]. GHK-Cu is not one of the six peptides in the HHS draft policy [18]. Compounded drugs are not FDA-approved, and FDA does not review their safety, effectiveness or quality before marketing [17].

HealthRX.com offers a copper peptide cream as a topical cosmetic.

Sport

WADA's Prohibited List names thymosin-beta4 and its derivatives, for example TB-500, in class S2.3; it is prohibited at all times, in and out of competition, and appears on the 2026 List and the 2027 List [9][20]. GHK-Cu is not named on the 2026 or 2027 List, but WADA's S0 class covers substances with no approval from any governmental health authority, and the 2027 explanatory notes say peptides not specifically named may still be prohibited [9][10].

Safety

FDA's stated concern for injectable TB-500 is immunogenicity, potentially amplified by peptide aggregation and impurities; it found no study of TB-500 immunogenicity or aggregation and no nonclinical toxicity studies [1]. There are no human pharmacokinetic or pharmacodynamic data for TB-500 by any route; animal studies indicate that subcutaneous or intraperitoneal TB-500 reaches the bloodstream and is broken down into smaller peptides, with no intramuscular animal studies found [1]. For injectable GHK-Cu, FDA says there are limited human data to inform safety-related considerations [15].

FDA's review of BPC-157 describes one case involving a product that contained TB-500. A 40-year-old woman used a research-only product containing BPC-157 and TB-500 (5 mg of each) injected subcutaneously twice daily and developed widespread skin hyperpigmentation and gum darkening within a week, which recurred when she tried the product again two weeks later; because the product contained two peptides, FDA said it cannot tell whether either caused it [3].