BPC-157vsTB-500
BPC-157 and TB-500 are the two compounds people reach for when something will not heal, and they are usually run together. Both have real human trial history. BPC-157's was an enema for ulcerative colitis. TB-500's used a different, much larger molecule, given as eye drops. Neither has been tested as an injection for a tendon.
- Healing and recovery
- Research only
- Both banned in sport
Both are sold for healing. Neither has been tested for it.
BPC-157's human trials tested the right molecule in the wrong place. TB-500's human trials tested the wrong molecule. No published human trial of either exists for a tendon, ligament or muscle injury.
| Attribute | BPC-157 | TB-500 |
|---|---|---|
| Length | 15 amino acids | 7 amino acids |
| Comes from | A protein found in stomach juice | A 43 amino acid protein called thymosin beta-4 |
| Sold for | Tendon, muscle and gut repair | Tendon, muscle and tissue repair |
| Tested in people as | An enema, for ulcerative colitis [1][2] | Eye drops and gels, and not this molecule [5][6] |
| Human trials of the thing sold | None | None |
| FDA status | Not approved. Recommended for compounding July 2026 [8] | Not approved. Recommended for compounding July 2026 [8] |
A recommendation for compounding is not approval. See section 09.
BPC-157
A chain of fifteen amino acids, based on a sequence found in a protein in human stomach juice. A fragment of something that protects your gut lining, studied for healing tendon, muscle and gut tissue. Its pharmaceutical name is PL 14736.
TB-500
A chain of seven amino acids, copied from the middle of a much larger protein called thymosin beta-4. The small working part of a protein your body already makes, the bit that helps cells move and rebuild.
TB-500 is not thymosin beta-4.
Thymosin beta-4 is a protein of 43 amino acids that your body makes in almost every cell. TB-500 is a chain of seven, copied from positions 17 to 23 of that protein, the part that binds actin. Its full name is Ac-LKKTETQ. This distinction decides which evidence applies to which product.
BPC-157 is the whole thing. Fifteen amino acids, and the same sequence that went into humans.
TB-500 is a seventh of a protein. Seven residues out of forty-three.
The trials used the protein, not the fragment. Every citation you see for thymosin beta-4 belongs to the larger molecule.
The fragment was made because short peptides are cheaper to synthesise, more stable and easier to characterise. That is a reasonable engineering choice. It is also why the two are not interchangeable when you go looking at evidence. When a product page cites the eye drop trials, or the wound healing trials, it is citing work on a molecule roughly six times the size of what is in the vial.
Both files are real. Neither is about what these are sold for.
Work begins in Croatia
Research starts at the pharmaceutical company Pliva on a fragment of a gastric protein. It carries the designations PL 14736, PL-10 and PLD-116 at different points.
Company development programmeSource type · industry research, not a published trial
Malinda wound healing study
Topical thymosin beta-4 closed wounds in rats about 42 percent faster than controls. Work on the full protein. [7]
J Invest DermatolSource type · animal study, peer reviewed
The first human study
PL 14736 is given rectally to healthy male volunteers and reported safe and well tolerated. [1]
Gut 2003;51(Suppl):A309Source type · conference abstract, methods never reviewed
- abstract only
- rectal route
- numbers never published
Phase 2, as an enema
A multicentre, randomised, double blind, placebo controlled Phase 2 trial of PL 14736 as an enema, for mild to moderate ulcerative colitis. The full trial data has never appeared as a paper. [2]
Gastroenterology 2005;128:A584Source type · conference abstract, full data unpublished
- randomised, placebo controlled
- abstract only
- gut, not tendon
RegeneRx human programmes
Several human programmes on the full protein: eye drops for dry eye and corneal wounds, topical gels for pressure ulcers, venous stasis ulcers and epidermolysis bullosa. The dermal formulation receives orphan drug designation. [5]
Ann N Y Acad Sci reviewSource type · peer-reviewed review of patient data, full protein
Esposito identifies what is in the vial
Mass spectrometry on TB-500 products, then independent synthesis to confirm the result. The answer is Ac-LKKTETQ. This is where TB-500 enters the scientific record as its own compound, and it happened because anti-doping laboratories needed to test for it. [11]
Drug Test Anal 2012;4(9):733-738Source type · analytical study, peer reviewed
A Phase 1 that never reported
A safety and pharmacokinetics trial in 42 healthy volunteers is registered. Its status is listed as unknown, it was reportedly cancelled the following year, and no results were ever published. [3]
ClinicalTrials.gov NCT02637284Source type · trial registration, no results
SEER-1 reaches Phase 3, and misses
The ophthalmic programme reaches Phase 3 in neurotrophic keratopathy, a corneal disease. Complete healing at four weeks in 6 of 10 treated patients against 1 of 8 on placebo. It missed its primary endpoint, at p = 0.0656. The trial had planned 46 patients and analysed 18, having closed early for slow recruitment. A secondary measure at day 43 did reach significance, at p = 0.0359. Published 2022. Still the full protein, still eye drops. [6]
Int J Mol Sci 2022 · PMC9820614Source type · human Phase 3, peer reviewed, primary endpoint not met
- randomised, placebo controlled
- primary endpoint missed
- 18 of 46 analysed
Category 2 at the FDA
The FDA places both in Category 2 of its 503A bulk substances list, the shelf for ingredients that may carry significant safety risks. [9]
FDA 503A category updateSource type · regulatory document
Off Category 2
Both come off Category 2 in a batch of twelve peptides, because the nominations were withdrawn rather than because anything was settled. [9]
FDA Category 2 removalsSource type · regulatory document
Advisory committee vote
The FDA's advisory committee recommends both for the compounding list, each by 8 votes to 6 with one abstention, against the advice of the FDA's own scientists, who recommended against all seven peptides heard. [8]
PCAC meeting record, 23–24 July 2026Source type · regulatory document, non-binding
Still nothing for a tendon
No published human trial of either compound for a tendon, ligament or muscle injury exists.
Two compounds sold for the same thing, and two different reasons the evidence does not reach it. BPC-157's human trials tested the right molecule in the wrong place. TB-500's human trials tested the wrong molecule. Both are sold as injections for tendons. Neither has been studied that way, in anyone. And the strongest trial in either file, the Phase 3 on thymosin beta-4, missed the mark it was designed to hit.
Everything that differs
| Attribute | BPC-157 | TB-500 |
|---|---|---|
| Sequence | GEPPPGKPADDAGLV, 15 amino acids | Ac-LKKTETQ, 7 amino acids |
| Also called | PL 14736, PL-10, PLD-116 | Thymosin beta-4 fragment, TB4 |
| Origin | A protein in gastric juice | Residues 17 to 23 of thymosin beta-4 |
| Is the sold molecule the tested one | Yes | No. The trials used the full 43 residue protein |
| Reported action | Tissue repair, gut protection, new blood vessel growth | Cell movement, tissue repair, new blood vessel growth |
| Human trials, route | Rectal, as an enema [1][2] | Eye drops and topical gels, on the parent protein [5][6] |
| Human trials, condition | Ulcerative colitis | Dry eye, corneal wounds, pressure ulcers, epidermolysis bullosa |
| How far development got | Phase 2, published only as conference abstracts | Phase 3 for eye conditions, on the parent protein, primary endpoint missed [6] |
| Trials for tendon or muscle | None | None |
| Animal evidence | Extensive, largely from one research group | Extensive, on the parent protein |
| FDA status | Not approved. Recommended for compounding 8 to 6 [8] | Not approved. Recommended for compounding 8 to 6 [8] |
| WADA status | Prohibited. Not named, caught by catch-all wording [10] | Named outright under S2.3, as a thymosin beta-4 derivative [10] |
How does each one work?
BPC-157
The theory is that BPC-157 encourages new blood vessels to form in damaged tissue and shifts the local balance of growth signals toward repair. More blood supply reaching a healing tendon means more of everything a repair needs.
The evidence for this is very large and almost entirely from rats. Tendon, muscle, gut, bone, even nerve. It also comes overwhelmingly from one research group in Croatia, which is not a criticism of the work but does mean it has not been independently reproduced at scale.
The two human studies measured safety and gut inflammation, not tissue repair.
TB-500
Thymosin beta-4 binds actin, the protein cells use as scaffolding when they move. By managing the supply of actin building blocks, it appears to help cells migrate into a wound and rebuild. It also encourages new blood vessels.
TB-500 is the part of the protein that does the actin binding. A 2010 review identified residues 17 to 23 as the functional core, and that finding is the reason the fragment was made. [16]
Whether a seven residue fragment does everything a 43 residue protein does is an open question. The fragment keeps the actin binding site. The rest of the protein was doing something, and what is lost by leaving it out has not been established in people.
What separates them
Five gaps, and the first two are the reason this page exists
Nobody has tested either for the thing they are sold for. No published human trial of BPC-157 or TB-500 for a tendon, ligament or muscle injury exists. What exists is case reports, clinic experience and animal work.
Nobody has tested TB-500 in people at all. The human trials belong to thymosin beta-4, the full protein. Whether the fragment behaves the same way is untested.
And the parent protein's best trial did not succeed. You will see the SEER-1 result quoted as 60 percent healing against 12.5 percent, which is 6 of 10 against 1 of 8. What usually gets left out is that this was the primary endpoint and it came in at p = 0.0656, above the 0.05 threshold the trial was measured against. Eighteen patients were analysed out of 46 planned. The result is encouraging and it is not a win. [6]
Nobody has tested them together. They are commonly run as a pair, and often sold premixed in blends. No trial has studied the combination.
And the route was never matched. BPC-157's human data came from an enema. Thymosin beta-4's came from eye drops and gels. These are sold as injections under the skin. How much reaches the target, and what it does on the way, changes with the method, which is why regulators treat routes as separate questions.
Thin human safety records, and a shared mechanism worth understanding
Reported effects
From the published human work, which was not injection.
- BPC-157 reported safe and well tolerated in its two studies [1][2]bpc-157
- Thymosin beta-4 reported safe and well tolerated as eye drops and gels [5][6]parent protein
- Injection site reactions commonly reported by users, not measured in trialsanecdote
- Neither has a documented pattern of serious effects, and neither has been watched closely enough to find onecaveat
Do not use
The shared mechanism is the reason.
- Active cancer, whether newly found or returnedavoid
- Pregnancyavoid
- Anyone subject to drug testing in sportavoid
- Both encourage new blood vessel growth, which is the healing claim and the caution at the same timemechanism
What is in the vial
Neither has an approved product to check against.
- Products sold as TB-500 have been analysed specifically, and the findings support treating the label as a claim rather than a fact [14]analysis
- Testing of seized peptides more broadly found purity between 5 and 75 percent, plus arsenic and lead [12]analysis
- One US lab reported problems in almost 30 percent of samples, including bacteria [13]testing
- A certificate of analysis tells you what the seller had tested, not what is in your vialcaveat
*Where this page says nothing is established, it means nobody has studied it. It does not mean a compound is safe.
The blood vessel point deserves a moment. Both compounds are believed to work partly by helping new blood vessels form. That is exactly what you want around a healing tendon, and exactly what you do not want around a tumour. Nobody is claiming these cause cancer. The caution exists because the mechanism cuts both ways and nobody has studied what happens over years. Our guide on reading a certificate of analysis covers what to actually check.
No ambiguity. Both are prohibited.
This reflects the 2026 Prohibited List, in force from 1 January 2026. WADA publishes a new list each September, so check the current version if you are reading this later in the year.
TB-500 is named outright. Section S2.3 covers growth factors and growth factor modulators, and it lists TB-500 directly. There is no ambiguity and no reading required.
BPC-157 is prohibited without being named. It does not appear by name in the 2026 list. It is caught anyway, in two possible places. S2.3 closes with a catch-all covering other growth factors or growth factor modulators affecting muscle, tendon or ligament protein synthesis, vascularisation or regenerative capacity, which describes what BPC-157 is sold to do. S0 covers substances with no approval from any government health authority. Either route reaches the same answer.
Everything in S2 is a non-specified substance, which carries a default four year ban for a first violation. This is not hypothetical: the Canadian Centre for Ethics in Sport has sanctioned an athlete for BPC-157 and TB-500 together, resulting in four years of ineligibility.
Detection is not theoretical either. Laboratory methods for finding TB-500 and its breakdown products in urine and plasma have been published since 2012. That is the reason the compound was chemically characterised in the first place. [11][15] This matters more here than on most pages, because these two are marketed hardest to exactly the people most likely to be tested. Contaminated research vials have also produced positive tests for compounds an athlete never intended to take.
The vote that everyone is misreading
It is a recommendation, not a decision. On 23 July 2026 the FDA's Pharmacy Compounding Advisory Committee recommended both BPC-157 and TB-500 for the 503A list, each by 8 votes to 6 with one abstention. The committee advises. The FDA then decides whether to open formal rulemaking, publish a proposed rule, take comment and publish a final rule. That typically runs 8 to 24 months. [8]
It is about compounding, not approval. A compounding pharmacy makes medicines to order for one patient with a prescription. The 503A list governs which raw ingredients it may use. It is not a finding that either compound is safe or effective for anything.
And it would not cover what most people buy. Even after rulemaking, a research chemical vial ordered online is not a compounded prescription from a licensed pharmacy.
Over two days the committee recommended six of the seven peptides it heard, going against its own FDA scientists, who had advised against all seven, citing short and underpowered studies. Headlines since have said the FDA cleared BPC-157 and TB-500. Neither compound is FDA approved. Neither may legally be compounded today.
Questions people ask
Should I use BPC-157 or TB-500?
Most protocols use both, on the reasoning that they work through different mechanisms. Neither has been tested in a person for the injuries people use them for, so there is no evidence to choose on.
Is TB-500 the same as thymosin beta-4?
No. Thymosin beta-4 is a protein of 43 amino acids. TB-500 is seven of them, positions 17 to 23. All the human trials used the full protein.
Does BPC-157 have human trials?
Yes, and they are not what most people think. It was given as an enema to people with ulcerative colitis, under the name PL 14736, and both studies appeared only as conference abstracts. The full Phase 2 data has never been published. A Phase 1 registered in 2015 was cancelled with no results.
Did the FDA just approve them?
No. An advisory committee recommended both for the compounding list in July 2026 by 8 votes to 6. That is advisory, it concerns compounding rather than approval, and rulemaking takes months.
Are they banned in sport?
Yes, both. TB-500 is named outright under section S2.3, as a derivative of thymosin beta-4. BPC-157 is not named, and it is caught by catch-all wording covering growth factors that affect tendon and muscle repair. Both carry a default four year ban.
I have seen a 60 percent healing figure for TB-500. What is that?
That comes from a Phase 3 trial of thymosin beta-4 eye drops for a corneal disease. It was 6 of 10 patients against 1 of 8 on placebo, and it missed its primary endpoint at p = 0.0656 with only 18 patients analysed. It is also the full protein rather than TB-500.
Why do they get sold together?
The reasoning is that BPC-157 works on tissue and blood supply while TB-500 works on cell movement, so they cover different parts of repair. Nobody has tested the combination in a person.
Should I be worried about the cancer caution?
No study shows either causes cancer. The caution exists because both are believed to encourage new blood vessel growth, which is what a tumour also needs, and nobody has studied long term use. If you have a cancer history, this is a conversation for a doctor.
What this page is built on
- 01Veljača M, Sladoljev D, Mildner B, et al. Safety, tolerability and pharmacokinetics of PL 14736, a novel agent for treatment of ulcerative colitis, in healthy male volunteers. Gut. 2003;51(Suppl):A309. Human study, rectal administration. Conference abstract, not a full paper.
- 02Ruenzi M, Stolte M, Veljaca M, Oreskovic K, Peterson J, Ulcerative Colitis Study Group. A multicenter, randomized, double blind, placebo-controlled phase II study of PL 14736 enema in the treatment of mild-to-moderate ulcerative colitis. Gastroenterology. 2005;128:A584. Human Phase 2 trial, enema. Conference abstract. Full data never published as a standalone paper.
- 03ClinicalTrials.gov NCT02637284. Safety and pharmacokinetics of PCO-02 (BPC-157) in healthy volunteers. Registered December 2015, 42 subjects. Status listed as unknown. Reportedly cancelled 2016. No results published.
- 04Sikirić P, et al. Focus on ulcerative colitis: stable gastric pentadecapeptide BPC 157. Curr Med Chem. 2012. PMID 22300085. Review by the primary research group.
- 05Treadwell T, Kleinman HK, Crockford D, Hardy MA, Guarnera GT, Goldstein AL. The regenerative peptide thymosin beta-4 accelerates the rate of dermal healing in preclinical animal models and in patients. Ann N Y Acad Sci. 2012. Review of preclinical and patient data on the full protein, applied topically.
- 06Sosne G, et al. 0.1% RGN-259 (thymosin β4) ophthalmic solution in neurotrophic keratopathy: a randomized, placebo-controlled, double-masked Phase III trial. Int J Mol Sci. 2022. PMC9820614. Trial SEER-1, NCT02600429. Human Phase 3, full protein, eye drops. 6 of 10 healed against 1 of 8 on placebo, p = 0.0656. Primary endpoint not met. 18 of a planned 46 patients analysed after early closure.
- 07Malinda KM, Sidhu GS, Mani H, et al. Thymosin beta4 accelerates wound healing. J Invest Dermatol. 1999. Animal study, full protein, topical.
- 08US Food and Drug Administration. Pharmacy Compounding Advisory Committee meeting and vote record, 23 to 24 July 2026. BPC-157 and TB-500 each recommended 8 to 6 with one abstention. Regulatory document. Non-binding recommendation, not approval.
- 09US Food and Drug Administration. 503A bulk drug substances category updates, September 2023, and Category 2 removals, April 2026, following withdrawal of nominations. Regulatory documents.
- 10World Anti-Doping Agency. The 2026 Prohibited List, effective 1 January 2026. Section S2.3 lists Thymosin-β4 and its derivatives e.g. TB-500, and closes with a catch-all covering other growth factors affecting muscle, tendon or ligament repair. Regulatory document.
- 11Esposito S, Deventer K, Goeman J, Van der Eycken J, Van Eenoo P. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential. Drug Test Anal. 2012;4(9):733-738. DOI 10.1002/dta.1402. Analytical study. Identified the contents of TB-500 as Ac-LKKTETQ by mass spectrometry, then synthesised it independently to confirm.
- 12Janvier S, Cheyns K, Canfyn M, Goscinny S, De Spiegeleer B, Vanhee C, Deconinck E. Impurity profiling of the most frequently encountered falsified polypeptide drugs on the Belgian market. Talanta. 2018;188:795-807. DOI 10.1016/j.talanta.2018.06.023. Peer-reviewed analytical study.
- 13NBC Washington. Lab finds problems in 30% of peptide vials tested. December 2024. News report of commercial laboratory testing, not peer reviewed.
- 14Delcourt V, et al. TB500/TB1000 and SGF1000: a scientific approach for a better understanding of misbranded and adulterated drugs. Drug Test Anal. 2023. DOI 10.1002/dta.3421. Peer-reviewed analytical study of what products sold under these names actually contain.
- 15Ho EN, Kwok W, Lau M, et al. Doping control analysis of TB-500, a synthetic version of an active region of thymosin beta 4, in equine urine and plasma by liquid chromatography-mass spectrometry. J Chromatogr A. 2012;1265:57-69. Analytical study establishing detection methods.
- 16Crockford D, Turjman N, Allan C, Angel J. Thymosin beta4: structure, function, and biological properties supporting current and future clinical applications. Ann N Y Acad Sci. 2010. Review identifying residues 17 to 23 as the actin-binding functional core.
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