Thymosin beta-4 vs TB-500 vs GHK-Cu: how do they compare?

Is thymosin beta-4 the same as TB-500?

Thymosin beta-4 and TB-500 are different molecules. Thymosin beta-4 is a natural protein of 43 amino acids (Low et al., Proceedings of the National Academy of Sciences, 1981). TB-500 is a seven-amino-acid fragment of it, positions 17 to 23, with an acetyl group on the first amino acid (Ho et al., Journal of Chromatography A, 2012). The FDA's briefing document (memo dated 15 May 2026) says websites 'often use the terms interchangeably' and that thymosin beta-4 and TB-500 'are not the same substance'. Sport Integrity Australia's thymosin beta-4 page (read 14 October 2026) lists TB4 and TB-500 as other names, so that one page treats them together.

The records treat the two differently. The October 2026 Poisons Standard lists them as separate entries, thymosin beta 4 at item 39 and TB-500 at item 38 of Appendix D, clause 5 (the Australian status of TB-500 gives the detail). The WADA 2026 Prohibited List names 'Thymosin-ß4 and its derivatives e.g. TB-500' in one line. The FDA briefing document reports that it identified no human studies of TB-500 (memo dated 15 May 2026), while published human trials exist for the full-length protein.

For the sequence letters, the acetyl tag and the 2012 papers that define TB-500, see the TB-500 and thymosin beta-4 sequence page.

How does GHK-Cu compare with TB-500?

GHK-Cu is a different molecule from TB-500. GHK is a human tripeptide, glycyl-L-histidyl-L-lysine, only three amino acids long, and GHK-Cu is the copper form of it (Pickart and Margolina, International Journal of Molecular Sciences, 2018; Tewari et al., American Journal of Sports Medicine, 2026). TB-500 has seven amino acids, an acetyl group and no metal. In a 2026 scoping review of six peptides that included both, 67% of identified publications used animal models and human clinical studies were limited to a handful of investigations, an overall proportion across six peptides that does not establish the proportion for either molecule separately; only the review's abstract was checked (Tewari et al., 2026). The TGA's advisory of 13 April 2026 names both TB-500 and GHK-Cu as examples of unapproved peptide products.

A 2018 narrative review focused on GHK collects reported tissue-repair and cell-protection findings for skin, lung connective tissue, bone, liver and stomach lining; the abstract names no models or study counts, the review is not a trial, and it does not establish a human result or compare GHK-Cu with TB-500 (Pickart and Margolina, 2018, abstract checked).

The FDA's safety-risk page (content current as of 22 April 2026) carries a route-specific GHK-Cu entry in its nominated-but-withdrawn table, as it does for TB-500, and says there are limited data in humans to inform safety-related considerations for that entry; the statement does not cover every formulation of GHK-Cu, and this page does not reproduce the route named in the entry. A text search of the Poisons Standard instrument F2026L01327 for 'GHK' on 14 October 2026 found no match, and this page does not assess whether any group entry covers GHK-Cu. The Australian peptide law page is the place for entry-by-entry status.

Evidence limits

What do these comparisons not show?

Every human result on this page describes full-length thymosin beta-4 or recombinant human thymosin beta-4, never TB-500. The FDA says acetylation changes a peptide's charge, size and binding, so a result for one form cannot be moved to another (FDA briefing document, memo dated 15 May 2026).

What have studies found about TB-500 in men?

The FDA's briefing document (memo dated 15 May 2026) reports that its search of PubMed, Embase and other databases found no article in which TB-500 was given to humans, and no study of TB-500 in men appears in the sources opened for this page. Full-length thymosin beta-4 was studied in healthy volunteers in early-stage trials. In the first part of a 2021 trial of recombinant thymosin beta-4 in 54 healthy Chinese volunteers, half were men and half were women, and the trial measured safety and blood levels, not any outcome specific to men and not TB-500 (Wang et al., Journal of Cellular and Molecular Medicine, 2021).

The FDA's briefing document lists the long set of conditions for which TB-500 is marketed online and reports finding no human article behind them. A 2026 scoping review of six musculoskeletal peptides found that 67% of identified publications used animal models and that human clinical studies were limited to a handful, most lacking robust controls, an aggregate across six peptides and not a figure for TB-500; only its abstract was checked (Tewari et al., 2026).

None of the study abstracts opened for this page reports a result for men on their own.

Have studies tested TB-500 for knee pain?

The sources opened for this page include no study of TB-500 for knee pain in people. The nearest published work is in rats, and neither study measured pain. In a 2026 study of 32 male rats after Achilles tendon repair, maximum load to failure at four weeks (measured on four tendons per group) was higher in the TB-500 group than in controls (p < 0.05), in what the authors call an exploratory study that does not describe people, using material the paper labels synthetic thymosin beta-4 (TB-500) without stating a sequence (Biçer et al., Joint Diseases and Related Surgery, 2026). In a 2013 study of rats with a cut medial collateral ligament, a knee ligament, healing tissue in the group given full-length thymosin beta-4 had higher mechanical properties at four weeks, a rat result for a different molecule from TB-500 that does not describe people, with the number of rats not stated in the abstract (Xu et al., Regulatory Peptides, 2013). A 2026 scoping review concluded that claims for such peptides in musculoskeletal recovery and performance 'remain unsubstantiated by current human trials'; only its abstract was checked (Tewari et al., 2026).

The Achilles study used 32 male rats in four groups of eight, measured load to failure on four tendons per group, and ran for four weeks. The authors call it exploratory, and the group given TB-500 together with BPC-157 showed no additional effect over either alone, in a rat model that does not describe people (Biçer et al., 2026).

One human study looked at thymosin beta-4 in knees without testing a treatment. The study measured higher thymosin beta-4 serum levels in 216 people with knee osteoarthritis than in 152 healthy controls, and thymosin beta-4 serum and joint-fluid levels were significantly correlated with X-ray severity grade among the patients, an observational association that does not establish a treatment or pain effect (Wei et al., Regulatory Peptides, 2013). That is a marker study of one design, and it tested no TB-500.

What have studies found about TB-500, thymosin beta-4 and the heart?

No published human heart-outcome result for TB-500 appeared in the sources checked on 14 October 2026. The heart studies cited here use full-length thymosin beta-4. In mice (number not stated in the abstract), thymosin beta-4 was followed by greater early heart-muscle cell survival and improved cardiac function after coronary artery ligation, a mouse result that does not show an effect in people (Bock-Marquette et al., Nature, 2004). In a 2025 randomised, placebo-controlled trial of 96 patients after a heart attack, recombinant human thymosin beta-4 was followed by a reduced infarct area at 90 days in a 43-patient subgroup, but the overall difference in infarct area across all 96 patients was not statistically significant, and the product was not TB-500 (Zhang et al., Cardiovascular Research, 2025).

Mouse work on the gene disagrees. One study identified thymosin beta-4 as essential for coronary vessel development in mice, with the number of mice not stated in the abstract, a mouse result that does not establish an effect in people (Smart et al., Nature, 2007). Another reported that knockout mice were viable and showed no altered vascular development in that group's own global and tissue-specific knockout lines, with the number of mice not stated in the abstract, a result in those lines that does not establish an effect in people and cannot be carried over to other mouse models (Banerjee et al., Circulation Research, 2013).

The human record starts with safety. In 54 healthy Chinese volunteers (Wang et al., 2021) and in four groups of 10 healthy volunteers (Ruff et al., 2010), the authors reported adverse events that were mild to moderate and no serious adverse events, in small groups and with products that were not TB-500. Both papers state a heart-attack research aim. The 2025 trial tested a different product from TB-500, so it says nothing about TB-500.

How long did studies take to measure an effect of TB-500?

The FDA's briefing document (memo dated 15 May 2026) reports finding no published study that gave TB-500 to people, so this page reports no onset time for TB-500. Animal and cell studies report fixed measurement points. In cultured fibroblasts (number of cultures not stated in the FDA summary), wound closure after 8 hours with TB-500 was not significantly different from vehicle, a cell result that does not establish an effect in an animal or a person (Rahaman et al., 2024, as summarised by the FDA). In a rat tendon study of 32 rats, outcomes were measured at four weeks, and the study does not describe people (Biçer et al., 2026). The TB-500 half-life page sets out every timing measurement found.