TB-500 (Thymosin Beta-4) UK
3 products from 3 brands · free UK delivery · EU 3–7 days
Every TB-500 (Thymosin Beta-4) listing compared
Last reviewed · prices and listings checked by Free Muscle
Strength and pack size as stated by each manufacturer. Total milligrams = strength per capsule multiplied by capsules per pack. Price per milligram is calculated from the current price. A dash means the manufacturer does not state that figure.
| Brand | Listing | Strength | Pack | Total | Price | £ per capsule | Per mg | Availability |
|---|---|---|---|---|---|---|---|---|
| Thoroughbred Labs | TB-500 Peptide Capsules | 0.3mg | 60 capsules | 18mg | £38.99 | £0.65 | £2.166 | In stock |
| Yakka Strength | TB-500 Peptide Capsules | 0.25mg | 60 capsules | 15mg | £46.99 | £0.78 | £3.133 | In stock |
| FreeMuscle | TB-500 — Thymosin Beta-4 · 60 Capsules | – | 60 capsules | – | £39.99 | £0.67 | – | In stock |
TB-500, also sold as thymosin beta-4 or Tβ4 and sometimes written TB500, is a synthetic peptide based on the actin-binding region of thymosin beta-4, a 43-amino-acid protein present in almost every cell of the body. It is studied in animal and cell models of wound repair and cell migration, and no version of it is an approved medicine. This page lists every brand of TB-500 stocked at Free Muscle, compared on pack size, form and batch testing, with links to the research and to the certificate for each batch.
What is TB-500?
Thymosin beta-4 is the body's main actin-sequestering protein. By binding G-actin it regulates how cells build their internal skeleton, which in turn affects cell migration, blood vessel formation and the inflammatory response. The product sold as TB-500 is not the full protein. Anti-doping chemists who characterised commercial TB-500 found it to be a short, N-terminally acetylated fragment covering residues 17 to 23 of thymosin beta-4, the segment that carries the actin-binding motif (Esposito 2012). That distinction matters, because most of the published biology concerns the full 43-residue protein rather than the fragment.
Full-length thymosin beta-4, international non-proprietary name timbetasin, has been given to people in a few small trials. An intravenous study in 40 healthy volunteers, with placebo in each cohort, found adverse events infrequent and mild or moderate, none serious, after single and then repeated administration over 14 days (Ruff 2010). A phase 2 trial of eye drops in nine people with severe dry eye found less discomfort and corneal staining than with vehicle drops, on 12 treated eyes against six (Sosne 2015). Nothing has been approved.
The fragment sold as TB-500 has no published human data at all, and the US FDA has stated that it identified no human exposure data for it. It is not a licensed medicine in the UK, the EU or the United States. Thymosin beta-4 and its derivatives, with TB-500 named as an example, are prohibited at all times under WADA class S2 (peptide hormones, growth factors and related substances).
PubChem records TB-500 under CID 62707662 and CAS number 885340-08-9: the N-acetylated seven-residue fragment Ac-LKKTETQ, formula C38H68N10O14, molecular weight 889.0 g/mol. Full-length thymosin beta-4 is a separate entry, CID 16132341 and CAS 77591-33-4, with the formula C212H350N56O78S and a molecular weight of about 4,963 g/mol.
What the published research reports
A 1999 study reported that topical or intraperitoneal thymosin beta-4 accelerated closure of full-thickness skin wounds in rats, with increased collagen deposition and keratinocyte migration (Malinda 1999). A 2004 study in Nature reported that thymosin beta-4 activated integrin-linked kinase, promoted cardiac cell migration and survival, and improved cardiac function after experimentally induced myocardial infarction in mice (Bock-Marquette 2004). A 2005 review summarised the protein's actin-sequestering role and its wound-repair activity across animal models (Goldstein 2005). All of this used the full protein, in animals, at doses and routes with no relation to any capsule product. The human studies of the full protein, an intravenous safety study and a small eye-drop trial (Ruff 2010; Sosne 2015), did not test the TB-500 fragment or any oral form, and no thymosin beta-4 product has been approved.
The other body of literature is analytical. The Ghent anti-doping laboratory identified the acetylated fragment in a TB-500 product, synthesised it as a reference and set out an LC-MS approach to detecting it in urine and plasma (Esposito 2012). After a single administration to horses, a Hong Kong racing laboratory found the fragment and its metabolites in both urine and plasma (Ho 2012).
A French racing laboratory noted that products sold online claim to contain either the fragment or the full protein, and showed that a synthesis impurity could be detected in a horse's plasma after one administration of a thymosin beta-4 product (Delcourt 2025). These studies say nothing about the products on this page.
- Malinda KM, et al. Thymosin beta4 accelerates wound healing. J Invest Dermatol. 1999;113(3):364-368. PMID: 10469335.
- Bock-Marquette I, et al. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432(7016):466-472. PMID: 15565145.
- Goldstein AL, Hannappel E, Kleinman HK. Thymosin beta4: actin-sequestering protein moonlights to repair injured tissues. Trends Mol Med. 2005;11(9):421-429. PMID: 16099219.
- Esposito S, et al. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500. Drug Test Anal. 2012;4(9):733-738. PMID: 22962027.
- Ho EN, et al. Doping control analysis of TB-500, a synthetic version of an active region of thymosin β4, in equine urine and plasma by liquid chromatography-mass spectrometry. J Chromatogr A. 2012;1265:57-69. PMID: 23084823.
- Ruff D, et al. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers. Ann N Y Acad Sci. 2010;1194:223-229. PMID: 20536472.
- Sosne G, Dunn SP, Kim C. Thymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial. Cornea. 2015;34(5):491-496. PMID: 25826322.
- Delcourt V, et al. Equine Doping Controls of Thymosin β4: A Population Study and Strategy for Misuse Detection. Drug Test Anal. 2025;17(7):1071-1077. PMID: 39314109.
Brands of TB-500 we stock
- Free Muscle TB-500 Thymosin Beta-4, 60 capsules. Free Muscle brand, capsule form, 60 capsules per pack. Every batch is assayed by Janoshik Analytical and the certificate for the batch you hold is sent on request.
- Thoroughbred Labs TB-500 Peptide Capsules. 60 capsules. Thoroughbred Labs states 300 mcg (0.3 mg) per capsule, which is 18 mg per pack. A COA is shown where Thoroughbred Labs supplies one for the batch we hold.
- Yakka Strength TB-500 Peptide Capsules. 60 capsules. Yakka Strength states 250 mcg (0.25 mg) per capsule, which is 15 mg per pack. A COA is shown where Yakka Strength supplies one for the batch we hold.
All three listings are capsules, but every published TB-500 or thymosin beta-4 study gave the peptide by infusion, eye drop, skin application or injection, never by mouth, so no study result describes a capsule. The Free Muscle TB-500 page compares capsules with vials, and our guide Do oral peptides actually work? explains what happens to peptides taken by mouth.
How to compare them
Where a strength per capsule is published, multiply it by the capsule count to get total milligrams and divide the price by that number for cost per milligram. Thoroughbred Labs states 300 mcg and Yakka Strength 250 mcg per capsule, so that arithmetic is possible for both. Where no strength is published, as with the Free Muscle listing here, the honest comparison is on documentation: whether an independent laboratory has tested the exact batch on sale, and whether the certificate names the batch number, the method, the purity found and a mass that matches the fragment rather than the full protein.
Ask for the certificate before you buy rather than after. Our UK supplier checklist sets out the other checks worth making on any listing.
Batch testing and certificates of analysis
A certificate of analysis (COA) sets out a laboratory's findings for a single manufactured batch: identity and purity (usually by HPLC and LC-MS), batch number, test date and laboratory. Free Muscle TB-500 is assayed batch by batch at Janoshik Analytical, an independent laboratory, and we email the certificate for your batch on request when you send the batch number from the label. Thoroughbred Labs and Yakka Strength listings display a COA only if the manufacturer has issued one covering the batch in stock; otherwise the field stays blank.
For TB-500 the identity result is the line to read first. The mass should match the acetylated seven-residue fragment, 889.0 g/mol (PubChem CID 62707662), not the 43-residue protein at about 4,963, because products sold online have claimed either one (Delcourt 2025). Without a batch number, a test date and a laboratory name, a report does not qualify as a batch certificate; the other points worth checking are listed on our lab tests page.
Where to buy TB-500 in the UK: how to check a supplier
Whichever shop you buy TB-500 from, check these five points before you order:
- A batch number and a certificate for that batch. The pack should carry a batch number, and the seller should be able to show a certificate of analysis for that same batch from a named laboratory, with the test date. Every Free Muscle-brand batch is assayed by Janoshik Analytical, and we send the certificate for your batch on request. For Thoroughbred Labs and Yakka Strength, a certificate is shown where the brand supplies one for the batch we hold.
- The strength per capsule and the capsule count. With both figures you can work out the total milligrams in the pack and the price per milligram; the comparison table above does this for every listing here that states both. If a listing does not state one of them, ask the seller before you order.
- Research-use labelling and an age check. A research compound should be sold for laboratory research use only, not for human consumption, to adults aged 18 or over, with no dosing or usage advice. That is how every listing here is sold.
- Prices in pounds sterling and tracked UK dispatch. UK delivery from us is free and tracked on every order, with no minimum spend, and usually arrives 2-3 working days after dispatch; orders placed before 2pm Monday to Friday are processed the same working day.
- A clear returns policy. Unopened items can be returned to us within 30 days.
Brands on this page: Free Muscle, Thoroughbred Labs and Yakka Strength. The UK supplier checklist and how we test go into more detail.
Legal status in the UK
TB-500 is not a licensed medicine in the UK and has no MHRA marketing authorisation. It is not an authorised food supplement and may not be sold for human consumption. It is supplied for laboratory research to adults aged 18 and over and is not a controlled drug. In sport it is prohibited at all times under WADA class S2, which names thymosin beta-4 and its derivatives, including TB-500, explicitly. For background on how peptides and SARMs are classified, see our SARMs versus peptides guide.
| Where | Status of TB-500 (checked October 2026) |
|---|---|
| United Kingdom | Not listed under the Misuse of Drugs Act 1971. No marketing authorisation; under regulation 46 of the Human Medicines Regulations 2012 an unauthorised medicinal product may not be sold or supplied, which rules out selling it as a medicine or for people to take. |
| European Union | No version is an approved medicine. |
| United States | Not FDA-approved. The FDA's compounding safety-risk page (last updated 22 April 2026) lists thymosin beta-4 fragment (LKKTETQ), also known as TB-500, among withdrawn nominations, citing possible immune reactions from aggregation, peptide impurities and no human exposure data identified. |
| Sport | WADA class S2.3, growth factors and growth factor modulators, on the 2026 Prohibited List: thymosin beta-4 and its derivatives, a group for which TB-500 is the example given. Prohibited at all times; S2 substances are non-Specified. Horseracing and equestrian federations also forbid thymosin beta-4 (Delcourt 2025). |
Storage and handling
Keep the container sealed, in a cool, dry place away from direct light, and return it there each time the container has been opened. Do not decant into unlabelled containers. Keep out of the reach of children and animals. Handle in line with ordinary laboratory good practice, with gloves and a clean work surface, and dispose of unwanted material through an appropriate waste route rather than down the sink.
Delivery and returns
Free Muscle is the trading name of FreeMuscle, a business registered in Andorra, with UK operations and dispatch in Scunthorpe. Every order ships with free tracked UK delivery in plain packaging with nothing on the outside to say what is inside. Orders placed before 2pm Monday to Friday are processed the same working day. EU delivery takes three to seven working days. Unopened items can be returned within 30 days. Customers must be 18 or over. Full details are on our shipping page and our guarantee page.
Related reading
- BPC-157 vs TB-500: what the studies compared
- TB-500 and thymosin beta-4: research summary and UK status
- Do oral peptides actually work? The honest answer
- BPC-157: what the research actually shows, and what it does not
- How to read a certificate of analysis
- Price per milligram: the only honest way to compare
- BPC-157, BPC-150, all peptides and IGF-1 LR3
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.
Research guides
Frequently asked questions
Is TB-500 legal in the UK?
This peptide is outside the Misuse of Drugs Act 1971, and holding it is not an offence under that law. It has no marketing authorisation, however, and regulation 46 of the Human Medicines Regulations 2012 forbids selling or supplying an unauthorised medicinal product; no food regulator has authorised it either, so it is not for human consumption. We supply it to adults aged 18 and over for laboratory use. In sport it is prohibited at all times under WADA class S2, which names TB-500 specifically.
Is TB-500 the same as thymosin beta-4?
Not exactly. Thymosin beta-4 is a 43-amino-acid protein found in most cells. Commercial TB-500 has been characterised by anti-doping chemists as a short, acetylated fragment covering residues 17 to 23, the actin-binding segment. Their molecular weights differ accordingly, about 889 g/mol for the fragment against about 4,963 for the full protein. Most published biology concerns the full protein, so results on thymosin beta-4 do not automatically apply to the fragment.
Is TB-500 a steroid, a SARM or a peptide?
A peptide. TB-500 is a seven-amino-acid sequence taken from thymosin beta-4, and its known biology concerns binding actin inside cells. It is not a steroid: steroids share a structure of four fused carbon rings and mostly act through hormone receptors in the cell nucleus. Nor is it a SARM, a synthetic non-peptide molecule designed around the androgen receptor. WADA reflects this by listing thymosin beta-4 and its derivatives under S2, growth factors, rather than S1, anabolic agents.
What is the difference between TB-500 and BPC-157?
Both are peptides studied in animal models of tissue repair, but they are unrelated sequences. BPC-157 is a fifteen-amino-acid fragment from a gastric protein; TB-500 is a fragment of thymosin beta-4, an actin-binding protein. Neither has a completed controlled human trial, and neither is an approved medicine anywhere.
What side effects has thymosin beta-4 shown in research, and is anything known about TB-500?
For full-length thymosin beta-4, a placebo-controlled intravenous study in 40 healthy volunteers found adverse events uncommon and mild or moderate in intensity, none of them serious, but it was small and covered only 14 days of administration. For the TB-500 fragment no human data exist: the US FDA has identified no human exposure data. A 2026 sports-medicine review found rigorous human safety data scarce for unapproved peptides, both of these included, and warned of potential for serious harm. The fragment's adverse effect profile is unknown.
Is TB-500 detectable in sport drug tests?
Yes. Anti-doping scientists in Ghent made the TB-500 fragment as a reference material and described a mass spectrometry method for blood plasma and urine, and a separate study found the fragment and its metabolites in horses after one administration. Nobody has published how long it remains detectable in people. TB-500 is prohibited at all times under WADA class S2, so a tested athlete should expect it to be looked for.
How do I verify the batch of TB-500 I receive?
Free Muscle TB-500 is assayed batch by batch at Janoshik Analytical, an independent laboratory; email us the batch number from your label and we will reply with that batch's certificate. Thoroughbred Labs and Yakka Strength TB-500 carry a manufacturer certificate on the product page only when one has been supplied for the batch in stock. In either case, a document without a batch number, a test date and a named laboratory is not evidence of testing.
Which TB-500 strength should I choose?
We leave that decision to the researcher and give no guidance on it. TB-500 is sold for laboratory research and this page describes the listings, not how to use them. What we can state is factual: pack size, form, whether the brand publishes a per-capsule figure at all, and what batch documentation exists. Thoroughbred Labs states 300 mcg per capsule and Yakka Strength states 250 mcg per capsule; the Free Muscle listing gives no per-capsule quantity, so for it the comparison rests on documentation.
Where can I buy TB-500 in the UK?
On this page you can compare every TB-500 listing we stock, from Free Muscle, Thoroughbred Labs and Yakka Strength. Every UK order ships free with tracking, with no minimum spend, and usually arrives 2-3 working days after dispatch. Everything here is supplied for laboratory research use only, not for human consumption, to adults aged 18 or over.
How fast is UK delivery?
UK delivery is free and tracked on every order, with no minimum spend, and usually arrives 2-3 working days after dispatch. Faster tracked UK delivery costs £6 and usually takes 1-2 working days. Orders placed before 2pm Monday to Friday are processed the same working day.
Do you deliver to Romania and the rest of the EU?
Yes. Orders to Romania and other EU countries travel by our paid, tracked international service and usually arrive 3-7 working days after dispatch; delivery to the rest of the world usually takes 5-14 working days. Prices are in pounds sterling (GBP). Rules differ in other countries, so check local law before ordering for delivery abroad.
Can I return an order?
Yes: unopened items can be returned within 30 days. Our guarantee page has the full policy.
Is there a discount when I buy more than one?
Yes, on Free Muscle-brand products: 5% off automatically when your cart holds 2 of them and 10% off with 3 or more, applied in the cart. The offers do not combine. Products from the other brands on this page are not included.