Last updated 10 October 2026 · SARMs Store editorial team. Products on this site are supplied strictly for laboratory research and are not for human consumption. This guide summarises published research; it is not medical advice and contains no instructions for use. 18+ only.
TB-500 at a glance
| Class | Synthetic fragment of thymosin beta-4 (actin-binding region, residues 17 to 23) |
|---|---|
| Parent protein | Thymosin beta-4, 43 amino acids, present in most cells |
| Highest evidence | Full protein: phase II human wound and eye trials; fragment: animal and cell studies only |
| Studied for | Cell migration, wound closure, cardiac repair in animal models |
| Format | Lyophilised vial (5mg, 10mg) or capsules |
| Storage | 2 to 8°C unopened, frozen long term, away from light |
| UK status 2026 | Research chemical; not a licensed medicine; WADA S2 |
What TB-500 is
TB-500 is the name used in the research supply market for a synthetic fragment of thymosin beta-4 (Tβ4), a 43-amino-acid protein found in almost every human and animal cell. The fragment most often sold corresponds to the actin-binding region of the full protein, amino acids 17 to 23, sometimes with an acetyl group. Thymosin beta-4 itself was isolated in the 1980s and has been the subject of several human trials; the shorter fragment has not. Buyers should keep the two apart when reading the literature, because most of the clinical work is on the full protein.
TB-500 names you will see
TB-500 is written TB500, TB 500 and TB-500, and it is often described as a thymosin beta-4 fragment or simply as TB4. Strictly, thymosin beta-4 (Tβ4) is the full 43-amino-acid protein, and TB-500 is the name the research market gives to a synthetic peptide based on its actin-binding region, the seven amino acids at positions 17 to 23 (LKKTETQ), sometimes with an acetyl group added. Some suppliers use the name for full-length synthetic thymosin beta-4 instead. The two are easy to tell apart on a proper certificate, because the full protein has a molecular mass of about 4.9 kDa and the fragment is under 1 kDa, so the certificate should state which one is in the vial. A different fragment, Ac-SDKP from the start of the protein, has its own literature on fibrosis and is not what TB-500 refers to.
What the research found
Mechanism. Thymosin beta-4 binds G-actin, the building block of the cell's internal scaffold, and by doing so regulates how cells move. That is the basis of every reported effect: cell migration into a wound, formation of new blood vessels, and reduced inflammation at the injury site. Goldstein and colleagues reviewed the biology in Expert Opinion on Biological Therapy in 2012.
Wound healing. Full-length Tβ4 accelerated dermal wound closure in rodent models and in a phase II human trial in pressure ulcers and venous stasis ulcers (published 2010 to 2012). A separate phase II programme in dry eye completed in the 2010s. These are trials of the full protein, not the fragment.
Heart. In mice, Tβ4 given after coronary artery ligation improved cardiac function and reduced scar size (Bock-Marquette et al., Nature, 2004). A human study in acute myocardial infarction was planned but the results have not established a clinical benefit.
The fragment. The 17 to 23 region retains actin binding in cell culture and has shown activity in some animal wound models, which is the rationale for TB-500. Controlled comparisons of fragment against full protein are few, and there is no human trial of TB-500 as sold.
Where the human evidence stands in 2026
All of the human data is for full-length thymosin beta-4, most of it from programmes run by the US company RegeneRx. A topical gel was tested in phase II trials in pressure ulcers, in venous ulcers (Guarnera and colleagues, Annals of the New York Academy of Sciences, 2010) and in the inherited skin disorder epidermolysis bullosa. Eye drops containing thymosin beta-4 were tested in dry eye and in neurotrophic keratopathy, a condition in which the cornea fails to heal, with mixed results across trials. An intravenous form was given to healthy volunteers in a placebo-controlled safety study (Ruff and colleagues, 2010). None of these programmes has produced a licensed medicine, and none tested the fragment sold as TB-500, so any statement about TB-500 in people is an extrapolation from a different molecule.
How TB-500 differs from BPC-157
They are unrelated molecules that appear together in the repair literature and are often bought together, which is why blends exist. BPC-157 is a gastric-derived pentadecapeptide with most of its evidence in rat gut and tendon models. TB-500 is an actin-binding fragment of a ubiquitous human protein with most of its evidence in wound and cardiac models, largely for the full protein. The Wolverine blend combines the two; there is no published study of the combination.
TB-500 compared with BPC-157, GHK-Cu and Thymosin Alpha-1
| Peptide | What it is | Main research area | Human data | In our range |
|---|---|---|---|---|
| TB-500 | Fragment of thymosin beta-4 | Actin binding, cell migration, wound and cardiac models | Full protein only, phase II | TB-500 5mg and 10mg vials, capsules |
| BPC-157 | Gastric-derived pentadecapeptide | Tendon, gut and blood vessel models | No completed controlled trial | BPC-157 5mg and 10mg vials, capsules |
| GHK-Cu | Copper-binding tripeptide | Skin, wound and matrix models | Small topical studies | GHK-Cu 50mg and 100mg vials |
| Thymosin Alpha-1 | 28-amino-acid thymus peptide | Immune cell signalling | Licensed abroad as thymalfasin | Thymosin Alpha-1 5mg vial |
Thymosin alpha-1 and thymosin beta-4 share a name because both were first isolated from thymus extracts, but they are unrelated molecules that do different things; see the Thymosin Alpha-1 guide. TB-500 also appears in the Wolverine, GLOW and KLOW blends, none of which has been studied as a combination.
Stability, storage and handling
TB-500 is supplied lyophilised in a sealed vial. Keep unopened vials refrigerated at 2 to 8 degrees Celsius or frozen, away from light. Once reconstituted in the laboratory it degrades over days to weeks. Purity by HPLC and identity by mass spectrometry are the two figures a certificate should show.
TB-500 in anti-doping and horse racing
TB-500 is prohibited at all times in human sport under section S2 of the WADA list, which names thymosin beta-4 and its derivatives. It has also been one of the most prominent peptides in horse racing regulation, where racing authorities in several countries have penalised trainers after TB-500 findings. Accredited laboratories have published methods that detect the fragment and its breakdown products in urine. Anyone subject to testing in any sport should treat it as prohibited.
Legal status in the UK, 2026
TB-500 is not a controlled drug under the Misuse of Drugs Act 1971 and is not a licensed medicine anywhere, so it cannot be sold or advertised for human use in the UK. It is sold strictly as a research chemical. In sport it is prohibited at all times under WADA section S2 (peptide hormones, growth factors and related substances), and it has produced several high-profile anti-doping cases in horse racing and human sport since 2011.
What to check before buying
Milligrams per vial, HPLC purity, mass spectrometry identity, a batch number that matches the certificate, and cold-chain shipping. Every Origin Peptides batch is independently tested and its certificate of analysis is published on the product page and the Lab Testing page.
Frequently asked questions
Is TB-500 the same as thymosin beta-4?
No. It is a synthetic fragment of it. Most published trials are of the full protein.
Has TB-500 been tested in humans?
The full protein has, in wound and eye indications. The fragment sold as TB-500 has not.
Can TB-500 and BPC-157 be studied together?
They are often combined in the research supply market (the Wolverine blend). No published study tests the combination.
Is TB-500 legal in the UK?
Legal to buy and possess as a research compound, not lawful to sell or advertise for human consumption, banned in sport.
What should a TB-500 certificate show?
Identity by mass spectrometry, which also shows whether the vial holds the fragment (under 1 kDa) or full-length thymosin beta-4 (about 4.9 kDa), purity by HPLC, and a batch number that matches the vial.
Are TB500 and TB-500 different products?
No. TB500, TB 500 and TB-500 are spellings of the same name.
Why is TB-500 banned in sport?
The WADA Prohibited List names thymosin beta-4 and its derivatives under section S2, peptide hormones, growth factors and related substances, so TB-500 is prohibited at all times.
Is TB-500 the same as Thymosin Alpha-1?
No. Both names come from the thymus, but thymosin alpha-1 is a separate 28-amino-acid peptide studied for immune signalling, while TB-500 is based on thymosin beta-4, which binds actin.
Key references
Goldstein AL, Hannappel E, Sosne G, Kleinman HK. Thymosin beta4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opinion on Biological Therapy. 2012;12(1):37-51. Bock-Marquette I, Saxena A, White MD, DiMaio JM, Srivastava D. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432(7016):466-472. Sosne G, Qiu P, Kurpakus-Wheater M. Thymosin beta 4: a novel corneal wound healing and anti-inflammatory agent. Clinical Ophthalmology. 2007;1(3):201-207. World Anti-Doping Agency. Prohibited List 2026, section S2.
Guarnera G, DeRosa A, Camerini R. The effect of thymosin treatment of venous ulcers. Annals of the New York Academy of Sciences. 2010;1194:207-212.
Ruff D, Crockford D, Girardi G, Zhang Y. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers. Annals of the New York Academy of Sciences. 2010;1194:223-229.
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- Peptides and muscle: what the studies show
- SARMs vs peptides: what the research compares
- BPC-157 research guide
- GHK-Cu research guide
- How to read a certificate of analysis
- SARMs 101 hub
Research products: Origin Peptides TB-500 5mg · TB-500 10mg · TB-500 capsules · Wolverine blend (BPC-157 with TB-500) · Full Origin Peptides range · Lab Testing