TB-500 vs thymosin beta-4: fragment and full protein compared

TB-500 research and research on thymosin beta-4 itself are generally described as being about different molecules, although the literature is not consistent. TB-500 is described in the analytical literature as a short, chemically modified piece of the full protein, while almost all of the wound-healing, heart and cell-migration findings come from the full-length protein. This guide separates the two, summarises what each body of evidence actually shows, and sets out what is still unknown. It also lists the adverse findings reported in the literature and compares the evidence for TB-500, BPC-157 and IGF-1 LR3. Listings (laboratory research only, 18+): TB-500 capsules compared.

Key takeaways

• TB-500 is described in doping-control papers as an N-terminally acetylated seven-amino-acid fragment (residues 17-23, LKKTETQ) of the 43-amino-acid protein thymosin beta-4 (Esposito et al., 2012; Ho et al., 2012; Mora et al., 1997 for the 43-residue length), although some papers use the names TB-500 and thymosin beta-4 interchangeably.
• Nearly all of the cell-migration, wound-repair and cardiac findings come from full-length thymosin beta-4 in cell cultures and animals, not from the fragment.
• No human trial of the TB-500 fragment was found in our PubMed searches on 2 October 2026. The human trials we found used the full protein, given intravenously, topically on skin, or as eye drops.
• The only TB-500-labelled efficacy paper in our source set is one exploratory rat tendon study with 32 animals (Biçer et al., 2026).
• Mendias and Awan (2026) reported that many unapproved peptides show favourable animal findings but that rigorous human safety data are scarce and there is potential for serious harm; Tewari et al. (2026), reviewing six peptides including TB-500, concluded that claimed benefits remain unsubstantiated by current human trials.
• No study in the set tested oral capsules of either molecule, so findings from injection, topical use or cell culture cannot be assumed to apply to a capsule.
• Thymosin beta-4 is described by an anti-doping paper as being on the World Anti-Doping Agency prohibited list, and the legal position in the UK depends on how a substance is presented and sold.
• The sections on TB-500 side effects reported in the research and on how TB-500 differs from BPC-157 and IGF-1 LR3 set out what each evidence base does and does not cover; no head-to-head human trial is in our source set.

What is TB-500?

Thymosin beta-4 is a naturally occurring peptide of 43 amino acids. It was first isolated from the thymus gland and later found in many tissues, where it acts mainly as an actin-sequestering molecule, meaning it binds actin (a structural protein in the cell skeleton) and keeps a pool of it unpolymerised (Mora et al., 1997). In plain English, it helps cells control how their internal scaffolding is built and rebuilt.

In the doping-control literature, TB-500 is treated as a different thing. Ho and colleagues describe TB-500 as a veterinary preparation whose key ingredient is N-terminally acetylated LKKTETQ (residues 17-23 of thymosin beta-4), describe that seven-residue segment as the active site within thymosin beta-4 responsible for actin binding, cell migration and wound healing, and developed a method to detect it in horse plasma and urine (Ho et al., 2012). Esposito and colleagues describe the N-terminal acetylated 17-23 fragment of human thymosin beta-4, written Ac-LKKTETQ, detected and identified it in a TB-500 product and synthesised it (Esposito et al., 2012). TB-500 is sometimes also written TB500. Mendias and Awan (2026) list it in their review as “TB-500 (thymosin beta-4 fragment)”. Not every paper draws the line this way, as the rat tendon and scoping-review sections below show.

Acetylation means a small chemical group has been attached to the start of the chain. Ho and colleagues describe the acetylation as artificial, that is, not how the segment occurs in nature. Ho et al. note that the preparation is marketed with biological claims; those claims were background to their analytical work and were not tested in the paper.

This distinction matters when reading TB-500 research summaries. A result in one body of work does not automatically transfer to the other. Papers on thymosin beta-4 and papers on TB-500 are more usefully read as different evidence, even though some use the names interchangeably, and this article keeps them apart where the papers allow.

How researchers think it works

The mechanisms below are hypotheses from laboratory and animal work, mostly on the full-length protein.

Actin binding and cell migration

Reviews describe thymosin beta-4 as being released by platelets, macrophages and other cells after injury, binding actin and promoting cell migration, including the movement of stem and progenitor cells (Goldstein et al., 2012). Ho et al. (2012) describe the 17-23 segment as the active site within thymosin beta-4 responsible for actin binding, cell migration and wound healing.

Inflammation, blood vessels and scarring

A review of animal studies lists down-regulation of inflammatory chemokines and cytokines, promotion of cell migration, blood vessel formation and cell survival as activities of the full protein (Philp and Kleinman, 2010). Another review adds that it was reported to reduce the number of myofibroblasts in wounds, cells associated with scar tissue (Goldstein et al., 2012).

An oxidised form with a different job

One laboratory study found that the oxidised form, thymosin beta-4 sulfoxide, triggered depletion of inflammatory macrophages at injury sites in zebrafish and mice, and in human immune-cell co-cultures it inhibited interferon-gamma and increased monocyte cell death (Evans et al., 2013). Evans et al. studied the oxidised form specifically, so their findings cannot be assumed to apply to unmodified thymosin beta-4 or to the fragment.

Rapid clearance

In mice given a single intraperitoneal injection of synthetic thymosin beta-4, serum levels rose within 2 minutes and the increase lasted 40 minutes. The authors concluded that the kidney rapidly removes the peptide from circulation (Mora et al., 1997). Mora et al. measured this in mice after intraperitoneal injection only.

Key studies at a glance

The evidence, study by study

There is no published human trial of TB-500, the 17-23 fragment, in the records we examined. Every human trial below used full-length thymosin beta-4 or a recombinant version of it. The preclinical papers follow, again mostly on the full protein. For the exact doses and schedules, please refer to each paper, which is linked below. The human trials come first, followed by the preclinical studies.

Ruff et al., 2010: intravenous phase I in healthy volunteers

This randomised, placebo-controlled phase I study enrolled four cohorts of ten healthy volunteers, who received a single intravenous administration of placebo or synthetic thymosin beta-4 at ascending levels and, after a safety review, the same regimen was repeated in a multiple-dose phase (regimen in the paper) (Ruff et al., 2010). The team recorded adverse events and pharmacokinetics. Adverse events were infrequent and mild or moderate, with no dose-limiting toxicities or serious adverse events. The single-dose pharmacokinetic profile was dose proportional and the half-life increased with dose.

The participants were healthy, the exposure was short, and the trial was designed to assess tolerability, not benefit.

Wang et al., 2021: recombinant protein in healthy Chinese volunteers

This first-in-human, randomised, double-blind phase I trial tested a recombinant human thymosin beta-4 called NL005 (Wang et al., 2021). Seven cohorts, 54 healthy people in all, received a single intravenous administration or placebo and were observed for 28 days. A separate group of 30 healthy people took part in a multiple-dose part, again with 28 days of follow-up.

Adverse events were mild to moderate, and there were no dose-limiting toxicities or serious adverse events. As with Ruff and colleagues, this was a tolerability study in healthy people, and it says nothing about whether the protein helps any condition.

Guarnera et al., 2007 and 2010: venous ulcers

The 2010 phase II trial was a double-blind, placebo-controlled, dose-escalation study at eight European sites in Italy and Poland, randomising 73 patients with venous leg ulcers to topical thymosin beta-4 or placebo (Guarnera et al., 2010). The safety profile at all levels was judged acceptable and comparable to placebo. The authors reported that complete healing can be achieved within 3 months in about 25% of patients, especially those with small to moderate or mild to moderate ulcers, and concluded that one level “may have the potential” to speed healing.

That phrasing is cautious for good reason. The abstract does not report a confirmatory result, and the trial was a phase II study. The 2010 abstract describes compression, dressings, debridement and infection control as the general standard of care for venous ulcers, and does not report a placebo healing rate, so the 25% figure cannot be read as a treatment effect. An earlier design paper described the planned study, with debridement if necessary and compression stockings as background care: 72 patients, with only 21 enrolled at the time of writing and no efficacy results (Guarnera et al., 2007).

Sosne and Ousler, 2015: dry eye, 72 subjects

This single-centre, double-masked, placebo-controlled phase II trial randomised 72 people with moderate to severe dry eye 1:1 to thymosin beta-4 eye drops or placebo (Sosne and Ousler, 2015). Neither primary endpoint, ocular discomfort or inferior corneal staining, differed significantly between groups. Among secondary endpoints, discomfort scores in the controlled adverse environment challenge were 27% lower than placebo (P = 0.0244), and central and superior corneal staining also differed (P = 0.0075 and P = 0.0210). No adverse events were observed.

Sosne et al., 2015: severe dry eye, nine patients

A separate small, multicentre, double-masked phase 2 trial treated nine patients with severe dry eye, including dry eye linked to graft-versus-host disease, with eye drops or vehicle and followed them to day 56 (Sosne et al., 2015). At day 56 the treated group (12 eyes) showed 35.1% less ocular discomfort than vehicle (6 eyes; P = 0.0141) and 59.1% less total corneal fluorescein staining (P = 0.0108). With nine patients, the findings are better treated as hypothesis-generating.

Preclinical studies

Biçer et al., 2026: the TB-500 rat tendon study

This is the only TB-500-labelled efficacy paper in our source set. Its abstract calls the compound “synthetic thymosin beta-4 (TB-500)”. Thirty-two male rats underwent Achilles tendon transection and repair and were randomised to four groups of eight: control, BPC-157, TB-500, or both. Treatments were given intraperitoneally and the tendons were assessed at four weeks (Biçer et al., 2026). The protocol doses are in the paper.

The abstract does not say whether the compound was the 17-23 fragment or the full protein; Tewari et al. (2026) likewise write “thymosin beta-4 or TB-500”.

The TB-500 group had higher maximum load to failure than controls (p < 0.05), a lower total Bonar score (p = 0.016) and a lower total Movin score (p = 0.017). The combined group had a lower Movin score (p = 0.040). The BPC-157 group showed numerically lower scores that did not reach significance for total scores, and combining the two compounds did not give extra benefit over either alone. Collagen type I expression did not differ significantly among groups.

The limitations are substantial. The authors call the work exploratory and its findings preliminary, with eight animals per group, a four-week window, and a need for dose optimisation and longer studies. It is a rat study; nothing in it was measured in people.

Peng et al., 2014: mouse myocardial infarction

In C57BL/6 mice with induced heart attack, full-length thymosin beta-4 delivered by osmotic minipump reduced cardiac rupture, which was associated with fewer infiltrating inflammatory cells and apoptotic myocytes; the mice were studied in two groups, with shorter and longer treatment (see the paper) (Peng et al., 2014). In the longer-treatment group the treated mice had less left ventricular dilation, better function, a markedly lower interstitial collagen fraction and higher capillary density. This is a single mouse model and used the whole protein, not the fragment.

Stark et al., 2016: a negative result in pigs

Pigs received thymosin beta-4 or vehicle and underwent cardiopulmonary bypass with aortic cross-clamping for 60 minutes, then were followed for 30 hours (Stark et al., 2016). Serum levels of the peptide rose, but cell death was not reduced and cardiac function and global myocardial blood flow were similar between groups. In vitro, high doses had a vasoconstrictor effect on mesentery arteries and a vasodilator effect on coronary arteries, and blood clot firmness fell when tested alongside an antiplatelet agent. The authors concluded that the cardioprotective effect seen elsewhere was not demonstrated in this model.

Reviews

Two review articles written by researchers in the field summarise the full-protein literature. One states that the protein has been used in several clinical trials and that applications in kidney, liver, spinal cord, bone and ligament are suggested by animal studies (Goldstein and Kleinman, 2015). Another describes trials in skin, eye, heart and brain as ongoing and projected (Goldstein et al., 2012).

Safety signals and what regulators and doping laboratories say

What the human trials reported

In healthy volunteers, Ruff et al. reported infrequent, mild or moderate adverse events and Wang et al. reported mild to moderate events; neither reported serious adverse events (Ruff et al., 2010; Wang et al., 2021). The topical and eye-drop trials reported acceptable tolerability. These findings relate to the named formulations, routes and populations. They do not describe the fragment, long-term exposure or any oral product.

Signals from animal and laboratory work, and a note on cancer biology

The pig study reported vascular effects of high levels in vitro and reduced clot firmness in the presence of an antiplatelet agent (Stark et al., 2016).

Separately, two laboratory and tissue studies link thymosin beta-4 expression to cancer cell migration or invasion; the papers do not address administered peptide. Overexpression of thymosin beta-4 increased migration of colon cancer cells and was linked to Rac1 activation and an ILK/IQGAP1 complex, with tumour staining suggesting a similar mechanism in tissue (Tang et al., 2011). In 76 colorectal carcinomas, immunoreactivity was detected in 59, and the highest expression was frequently seen in invading cells with features of epithelial-mesenchymal transition (Nemolato et al., 2012). These are a cell-model study with tissue staining and a human biopsy study; neither tested an administered peptide, and whether giving the peptide changes cancer risk in people is not known. In the Nemolato et al. abstract, expression at mRNA level, compared in four cases of colon cancer, did not differ significantly between surrounding mucosa and tumour samples.

What reviewers say

A narrative review in Sports Medicine covering approved and unapproved peptides, including thymosin beta-4 and TB-500, reported that many unapproved peptides show favourable tissue-repair outcomes in animals, but rigorous human safety data are scarce and there is potential for serious harm (Mendias and Awan, 2026). It describes a “gray market” of unapproved compounds operating largely outside regulatory oversight.

A scoping review in the American Journal of Sports Medicine of six peptides, including TB-500, found that 67% of identified publications used animal models, that human studies were few and mostly lacked robust controls, and that claimed benefits remain unsubstantiated by current human trials. It concluded that peptide supplements should not currently be recommended in place of, or alongside, standard orthopaedic care (Tewari et al., 2026). Anecdotal reports from individuals are not evidence of efficacy or safety, and we do not cite them.

What doping laboratories report

Doping-control chemists have built detection methods for TB-500 and for thymosin beta-4. In horses given a single administration of a TB-500 preparation, the acetylated fragment and its metabolites were detected in urine and plasma (Ho et al., 2012). For the full protein, a metabolite called Ac-Tbeta1-14 was found in urine from rats given the protein by injection, was quantifiable up to 48 hours with the highest level in the first 6 hours, and was not detected in untreated controls including human blank urine (Rahaman et al., 2023).

What the research does not tell us

The evidence hierarchy

Animal and cell studies cannot show what happens in people. For TB-500, the set holds one exploratory rat study of a compound its authors label TB-500 (the abstract calls it “synthetic thymosin beta-4 (TB-500)” and does not state the sequence) plus analytical chemistry. The full protein reaches phase I and phase II human trials, and no further in the records we fetched.

Route and formulation

In the abstracts we read, the administered-peptide findings used intraperitoneal injection or minipump delivery (rodents), systemic dosing in pigs, intravenous administration (healthy volunteers), topical application to skin or eye, or cell and tissue systems; the Evans et al. and Ho et al. abstracts do not state a route. No study in the set tested oral capsules or powder of either TB-500 or thymosin beta-4, so none of these findings can be assumed to carry over to an oral capsule. The mouse biodistribution work, after intraperitoneal injection, concluded that the kidney clears the peptide quickly (Mora et al., 1997). For a broader discussion of the oral question, see our explainer Do oral peptides work?

Specific gaps

• No human efficacy trial of thymosin beta-4 for muscle, tendon or athletic outcomes exists in the set.
• Human trials of the full protein were short or small (phase I in healthy volunteers, phase II in small patient groups), so long-term safety is unknown, and the dry-eye trial missed its primary endpoints (Sosne and Ousler, 2015).
• A negative preclinical result exists (Stark et al., 2016), so positive animal findings are not uniform.
• Whether the cancer-related laboratory findings matter for administered peptide is unknown.
• Content, purity and strength of any particular commercial product are not established by these papers, and no oral data were found.

TB-500 results: what the studies actually measured

The literature gives several answers to a search for TB-500 results, because the studies used different molecules, species and outcomes, and only one of the outcome studies below used a compound its authors called TB-500. This section groups what was measured by population and design, with the adverse findings and limits beside it. Protocol details are in the linked papers.

Animal studies

In the TB-500-labelled rat study (32 rats, Achilles tendon cut and repaired, four weeks), the TB-500 group had a higher maximum load to failure and lower Bonar and Movin histology scores than controls, while collagen type I expression did not differ significantly among groups (Biçer et al., 2026); the figures are in the evidence section. In mice with an induced heart attack, full-length thymosin beta-4 was followed by less cardiac rupture and, in the longer-treatment group, higher capillary density (Peng et al., 2014). In pigs undergoing bypass surgery, the same protein did not reduce cell death, and cardiac function and blood flow were similar between groups (Stark et al., 2016).

Healthy volunteers and patients (full-length protein only)

The two phase I studies in healthy volunteers measured tolerability and pharmacokinetics, not benefit (Ruff et al., 2010; Wang et al., 2021). In 72 people with dry eye, neither primary endpoint differed between eye drops and placebo, while a secondary discomfort score was 27% lower (P = 0.0244) (Sosne and Ousler, 2015). In a nine-patient trial in severe dry eye, discomfort was 35.1% lower and corneal staining 59.1% lower than with vehicle at day 56 (Sosne et al., 2015). In 73 patients with venous ulcers, complete healing within three months was reported in about 25%, with no placebo rate in the abstract (Guarnera et al., 2010).

Adverse findings and limits

The rat study's authors called their work exploratory and preliminary, with eight animals per group. The pig study reported vascular effects at high concentrations in vitro and reduced clot firmness with an antiplatelet agent. The larger dry-eye trial missed its primary endpoints, and the other had nine patients. Tewari et al. (2026) concluded that claimed benefits remain unsubstantiated by current human trials. No study in the set tested the fragment in people or tested an oral capsule, so none of these results can be assumed to apply to one. The adverse findings are tabulated in the next section.

TB-500 side effects reported in the research

No study in our source set reports adverse effects of the TB-500 fragment in people, so the table lists what was reported for full-length thymosin beta-4 and for the wider peptide class. Each row describes a named group in a named study, not what any reader would experience.

Our source set contains no case report of an adverse event attributed to TB-500. A case report describes one patient or a few. It can flag a possible signal, but it cannot show how often an event occurs, whether a product caused it, or what the product contained, which Moiz et al. (2026) flag as a risk with unregulated peptides. The absence of a case report is not evidence that no harm occurs.

The data gaps are substantial. No trial of the fragment in people was found. The full-length protein was studied in short phase I trials in healthy volunteers and in small patient groups, and Wang et al. assessed anti-drug antibodies although the abstract does not report that result. No study in our source set examined long-term exposure or oral products, and the set does not show whether giving the peptide changes cancer risk in people.

TB-500 vs BPC-157 vs IGF-1 LR3: how they differ

These three names are often discussed together, but they are different molecules with different evidence bases. The table describes what the papers in our source set say about each. It is not a ranking.

There is no head-to-head human trial of any pair in our source set. The only study that placed TB-500 and BPC-157 in one design is the rat tendon study, with eight rats per group. Each treatment group was compared with controls, and the combination did not add benefit over either alone (Biçer et al., 2026). The authors called it exploratory, so it does not rank the compounds and says nothing about people. No study in the set compares either peptide with IGF-1 LR3.

Villegas Meza et al. (2026) described regenerative peptides such as BPC-157 and thymosin derivatives as investigational, with uncertain safety profiles, product quality concerns and widespread anti-doping restrictions. Dominikowski et al. (2026) reviewed growth hormone and IGF-1 axis peptides, including IGF-1 LR3, and reported endocrine and metabolic disturbances, fluid retention and injection-site reactions across that class; the abstract does not attribute them to LR3 alone. For each comparator, as summarised in our BPC-157 research overview and our IGF-1 LR3 research explained article, most evidence is from animals or cells, and results from those routes cannot be assumed to apply to an oral capsule.

Legal status

Is TB-500 legal in the UK? See our TB-500 UK legal status guide, which sets out the primary legislation and what could not be verified. This is general information, not legal advice.

About the Free Muscle TB-500 listings

Free Muscle sells research compounds and gym apparel online at freemuscle.co.uk. The listing relevant to this article is TB-500 Thymosin Beta-4, 60 capsules. The product page states 60 capsules; strength is not stated on that page. The listing name combines both terms. See also the peptides collection.

Research compounds sold by Free Muscle are supplied for laboratory research use only and are not for human consumption. They are not authorised as medicines by the MHRA, EMA or FDA, are not food supplements, and are sold only to adults aged 18 or over. Nothing on this page is medical or dosing advice.

Every Free Muscle batch of research compounds is assayed for identity and purity by Janoshik Analytical, an independent laboratory. The Certificate of Analysis for a batch is sent on request: email the batch number printed on the label together with the product name. Details are on the lab tests page, and see the guide how to read a certificate of analysis. Also: what is Janoshik Analytical.

UK delivery is free and tracked, in plain packaging. Standard UK delivery takes 2 to 5 working days, and orders placed before 2pm UK time Monday to Friday are processed the same working day (see shipping information). Returns: returns within 30 days (unopened items in original packaging). Related reading: BPC-157: what research shows.

Frequently asked questions

What is TB-500 in research literature?

Ho et al. (2012) describe it as a veterinary preparation whose key ingredient is N-terminally acetylated LKKTETQ, residues 17-23 of thymosin beta-4. Esposito et al. (2012) describe the N-terminal acetylated 17-23 fragment of human thymosin beta-4, written Ac-LKKTETQ, identified in a TB-500 product.

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

Doping-control papers and Mendias and Awan (2026) describe TB-500 as a seven-residue fragment of thymosin beta-4, a 43-amino-acid protein, but some papers use the two names interchangeably (Biçer et al., 2026; Tewari et al., 2026). Most published efficacy and safety data are for the full protein.

Has TB-500 been tested in human clinical trials?

We found none on PubMed on 2 October 2026. Human trials identified used full-length thymosin beta-4 or a recombinant version, given intravenously, topically or as eye drops, and reached phase I or phase II only.

What did the rat tendon study find?

In 32 rats with a surgically repaired Achilles tendon, the TB-500 group had higher maximum load to failure than controls (p < 0.05) and lower Bonar and Movin histology scores. The authors called the work exploratory and preliminary (Biçer et al., 2026). This was an animal study with eight rats per group; nothing was measured in people, and the findings cannot be assumed to apply to humans or to an oral product.

Is there research on thymosin beta-4 capsules?

No study in our source set tested oral capsules of thymosin beta-4 or TB-500. Findings from injection, topical use or cell culture should not be assumed to apply to oral products.

Why do anti-doping laboratories study TB-500?

The formulation was suspected of being used as a doping agent in sport, so Esposito et al. identified and synthesised its acetylated fragment (Esposito et al., 2012), and Ho et al. developed a method to detect it and its metabolites in horse urine and plasma (Ho et al., 2012).

What do recent reviews conclude about peptides like TB-500?

Mendias and Awan reported that many unapproved peptides show favourable animal findings but that rigorous human safety data are scarce, and Tewari et al. concluded that the claimed benefits of the six peptides they reviewed remain unsubstantiated by current human trials; see what reviewers say for the details.

Is TB-500 legal to sell in the UK?

According to the legislation linked in the legal section above, whether a product is a medicinal product depends on its function and presentation, and we cannot say how TB-500 is classified; see the legal section. Under the Human Medicines Regulations 2012, whether a product is a medicinal product depends on its function and presentation (regulation 2), and regulation 46 addresses the sale or supply of unauthorised medicinal products. Our longer discussion is in the TB-500 UK legal status guide. This is general information, not legal advice.

What are the reported TB-500 side effects?

No study in our source set reports adverse effects of the TB-500 fragment in people. For full-length thymosin beta-4, the phase I trials in healthy volunteers reported mild to moderate adverse events and no serious ones (Ruff et al., 2010; Wang et al., 2021). Reviews describe scarce human safety data and potential risks of unregulated products; see the side-effects table for each finding and its limits.

How does TB-500 differ from BPC-157?

They are different molecules. TB-500 is described as a fragment of thymosin beta-4 with actin-binding activity (Ho et al., 2012), while BPC-157 is a synthetic pentadecapeptide studied for VEGFR2 and Akt-eNOS signalling (McGuire et al., 2025). The only study to place both in one design was a rat tendon study, and no head-to-head human trial is in our source set. See the comparison section.

What do TB-500 results in the published studies show?

The published studies differ in molecule, species and outcome, and only one outcome study, the rat tendon study, used a compound its authors called TB-500; the rat study figures are in the answer on the rat tendon study above. See what the studies actually measured for the grouped results and their limits.

What does thymosin beta-4 do, according to the research?

Thymosin beta-4 was described as functioning mainly as an actin-sequestering molecule in nonmuscle cells, keeping a pool of unpolymerised actin (Mora et al., 1997). A review described thymosin beta-4 as released from platelets, macrophages and other cell types after injury, as binding actin and as promoting cell migration (Goldstein et al., 2012). These are descriptions from the published literature and cannot be assumed to apply to people or to an oral product.

Does TB-500 show up in anti-doping tests?

Doping-control laboratories have published detection methods. One study detected the acetylated fragment and its metabolites in plasma and urine from horses given a single administration of a TB-500 preparation (Ho et al., 2012), and another found a metabolite of the full-length protein in rat urine that was absent from untreated controls, including human blank urine (Rahaman et al., 2023). Our sources report no validated human test result for the fragment. Whether a substance is prohibited in sport is a matter for the World Anti-Doping Agency and UK Anti-Doping; check their current published lists. This is general information, not legal advice.

Does this article give instructions or doses for TB-500?

No. This article prints no doses, schedules or protocols; the study protocols are in the papers linked above. TB-500 is sold by Free Muscle for laboratory research use only, to customers aged 18 or over, and is not for human consumption. Nothing here is medical advice.

Related reading

• Short overview: TB-500 and thymosin beta-4: research summary and UK status

Sources

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