{"shortAnswer":"TB-500 is in limbo: it is not approved, and it is on neither FDA list for compounding, so no pharmacy may lawfully make it. The evidence grade is animal-only. No study has given it to people, so nobody knows if it helps or how safe it is.","url":"https://peptideindex.ai/compound/tb-500","status":"limbo","statusCheckedAt":"2026-10-25T23:50:29.974Z","statusStale":false,"regulatoryAsOf":"2026-10-23","verified":"2026-10-25T23:50:30.004Z","primarySourceUrl":"https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks","clinicallyReviewed":false,"notice":"Information, not medical advice.","id":"fa75bf41-2f15-4598-bdb0-dc9dc1b6294e","object":"compound","slug":"tb-500","name":"TB-500","attrs":{"name":"TB-500","class":"healing-and-repair","access":[{"type":"none","detail":"There is no legal route to TB-500 in the US today. It is in no approved drug, has no official quality standard, and is not on the list pharmacies may use.","source_url":"https://www.fda.gov/media/193349/download"}],"trials":[],"aliases":["TB500","TB-500 free base","TB-500 acetate","thymosin beta-4 fragment (LKKTETQ)"],"summary":"A lab-made chain of seven amino acids copied from a small part of a natural protein. It is in no FDA-approved drug. It is sold for injury recovery.","citations":[{"n":1,"url":"https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks","tier":"primary","type":"regulatory","title":"FDA: bulk drug substances that may present significant safety risks, including those withdrawn from Category 2"},{"n":2,"url":"https://www.fda.gov/media/94155/download","tier":"primary","type":"regulatory","title":"FDA: bulk drug substances nominated under section 503A, list updated 14 May 2026"},{"n":3,"url":"https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act","tier":"primary","type":"regulatory","title":"FDA: bulk drug substances used in compounding under section 503A"},{"n":4,"url":"https://www.federalregister.gov/documents/full_text/html/2026/04/16/2026-07361.html","tier":"primary","type":"regulatory","title":"Federal Register: notice of the July 2026 Pharmacy Compounding Advisory Committee meeting"},{"n":5,"url":"https://www.fda.gov/advisory-committees/advisory-committee-calendar/july-23-24-2026-meeting-pharmacy-compounding-advisory-committee-07232026","tier":"primary","type":"regulatory","title":"FDA: Pharmacy Compounding Advisory Committee meeting, 23 and 24 July 2026"},{"n":6,"url":"https://www.fda.gov/media/193349/download","tier":"primary","type":"regulatory","title":"FDA briefing document on TB-500 for the July 2026 committee meeting, 15 May 2026"},{"n":7,"url":"https://www.fda.gov/media/193711/download","tier":"primary","type":"regulatory","title":"FDA: questions put to the committee at the July 2026 meeting"},{"n":8,"url":"https://www.fda.gov/media/193773/download","tier":"primary","type":"regulatory","title":"FDA: presentations to the committee on 23 July 2026, including TB-500"},{"n":9,"url":"https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/warrior-labz-sarms-655280-06122023","tier":"primary","type":"regulatory","title":"FDA warning letter to an online seller that listed TB-500, 12 June 2023"},{"n":10,"url":"https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/peptide-partners-llc-735063-08242026","tier":"primary","type":"regulatory","title":"FDA warning letter to an online seller of research-use peptides, 24 August 2026"},{"n":11,"url":"https://www.mcdermottlaw.com/insights/bulk-list-bound-pcac-backs-majority-of-peptides-in-two-day-public-meeting/","tier":"legal-analysis","type":"legal-analysis","title":"McDermott Will & Schulte: what the July 2026 committee votes on peptides mean"},{"n":12,"url":"https://www.thefdalawblog.com/2026/07/peptide-l-wave-pcac-approves-four-bulk-drug-substances-for-the-503a-list/","tier":"legal-analysis","type":"legal-analysis","title":"FDA Law Blog: the committee recommends four peptides for the 503A list"},{"n":13,"url":"https://www.sheppard.com/insights/blogs/fda-balances-peptide-policy-with-enforcement-against-unlawful-peptide-sellers","tier":"legal-analysis","type":"legal-analysis","title":"Sheppard Mullin: FDA's peptide policy and its warning letters to peptide sellers"},{"n":14,"url":"https://pubmed.ncbi.nlm.nih.gov/42542926/","tier":"peer-reviewed","type":"animal","title":"TB-500 and BPC-157 on Achilles tendon healing in rats, 2026"},{"n":15,"url":"https://pubmed.ncbi.nlm.nih.gov/12581423/","tier":"peer-reviewed","type":"animal","title":"Thymosin beta-4 and a seven-amino-acid piece of it on skin wounds in diabetic and aged mice, 2003"},{"n":16,"url":"https://pubmed.ncbi.nlm.nih.gov/22962027/","tier":"peer-reviewed","type":"in-vitro","title":"Identifying the thymosin beta-4 fragment in TB-500 for sport testing, 2012"},{"n":17,"url":"https://pubmed.ncbi.nlm.nih.gov/36482504/","tier":"peer-reviewed","type":"in-vitro","title":"Lab analysis of mislabeled and impure TB500 products sold online, 2023"},{"n":18,"url":"https://pubmed.ncbi.nlm.nih.gov/23050815/","tier":"peer-reviewed","type":"reference","title":"Review: full-length thymosin beta-4 and skin healing in animals and patients, 2012"},{"n":19,"url":"https://pubmed.ncbi.nlm.nih.gov/25826322/","tier":"peer-reviewed","type":"rct","title":"Thymosin beta-4 eye drops for severe dry eye: a small randomized trial, 2015"},{"n":20,"url":"https://pubmed.ncbi.nlm.nih.gov/34346165/","tier":"peer-reviewed","type":"human-trial","title":"First test of full-length thymosin beta-4 in healthy volunteers, 2021"},{"n":21,"url":"https://www.nbcnews.com/health/health-news/peptides-restrictions-ease-fda-panel-recommend-bpc-157-scientists-rcna588879","tier":"established-news","type":"reference","title":"NBC News: FDA panel recommends easing peptide limits despite agency scientists"},{"n":22,"url":"https://www.npr.org/2026/07/23/nx-s1-5903202/fda-peptides-restrictions","tier":"established-news","type":"reference","title":"NPR: FDA advisers back easing limits on six peptides, 23 July 2026"}],"known_risks":["FDA warns that a peptide shot like TB-500 may set off the immune system. Peptides can clump together, which can make this worse [^6].","FDA says the name TB-500 is used for more than one substance. A product sold as TB-500 may not hold the form a doctor ordered [^6].","A lab that tested TB-500 products sold online found their contents did not always match what they claimed to be [^17].","FDA warns that shots made outside drug rules can carry germs or toxins straight into the blood. That can cause a life-threatening infection [^9]."],"short_answer":"TB-500 is in limbo: it is not approved, and it is on neither FDA list for compounding, so no pharmacy may lawfully make it. The evidence grade is animal-only. No study has given it to people, so nobody knows if it helps or how safe it is.","evidence_grade":"animal-only","open_questions":["No study has given TB-500 to people, so nobody knows if it helps any human illness or what harm it does [^6].","No animal study has checked TB-500 for harm to organs, genes or unborn babies, or for cancer [^6].","In one lab test on skin cells, TB-500 did not help a scratch close. Nobody knows if it heals wounds in a living body [^6].","The body breaks TB-500 into smaller pieces. Nobody knows if TB-500 would act on its own or only through one of those pieces [^6]."],"section_routes":"There is no legal way to get TB-500 in the US today [^6]. No approved drug contains it, here or in ten other countries FDA checked [^6]. A pharmacy may use a substance with no official quality standard only if it is in an approved drug or on the federal list. TB-500 is neither [^3] [^6]. That could change if FDA adds it by writing a rule after the committee vote [^11] [^12].\n\nFDA found no clinical study of TB-500 in people [^6]. Trials of full-length thymosin beta-4 test a different molecule, so they are not listed here. Any open TB-500 trial would appear in the trials block below, with the date the official registry was last checked.","regulatory_as_of":"2026-10-23","section_channels":"People who use TB-500 get it in three main ways [^6] [^9]. The first is online sellers that label it for research use only. FDA has warned a seller of TB-500 that this label does not make it legal to sell a drug meant for people [^9] [^13]. The second is pharmacies. Two websites say they get TB-500 from a compounding pharmacy, though FDA found no pharmacy that markets it [^6]. The third is websites where people book an online visit to discuss using it [^6].\n\nIn all three, nobody checks what is in the product the way FDA checks an approved drug. A lab found that TB-500 products bought online did not always hold what they claimed [^17]. FDA found two reports of problems with a TB-500 and BPC-157 blend, with no assessment of harm [^6]. FDA does not get every report of harm, especially for compounded products, so these files cannot show how often harm happens [^6].","section_evidence":"The evidence grade is animal-only: FDA found no study of TB-500 in people [^6]. One rat study, published in July 2026, tested a substance it calls synthetic thymosin beta-4 (TB-500) [^14]. Its summary does not say whether that was the seven-amino-acid piece. Most other studies cited for TB-500 used a different molecule. They are named below as borrowed evidence.\n\nThe rat study: in rats whose Achilles tendon was cut and repaired, shots into the belly cavity gave stronger, more orderly tendons after four weeks [^14]. The authors call this an early result that needs more study [^14]. In a lab test on skin cells, TB-500 itself did not help a scratch close [^6].\n\nBorrowed evidence: a 2003 mouse study tested thymosin beta-4 and a seven-amino-acid piece of it on skin wounds, and both sped healing [^15]. That piece lacks TB-500's chemical change, so FDA says its results do not carry over to TB-500 [^6]. A review reports that full-length thymosin beta-4 sped healing in animals and in two trials in people with skin ulcers [^18]. In 9 people with severe dry eye, thymosin beta-4 eye drops eased symptoms [^19]. In healthy volunteers, thymosin beta-4 given into a vein caused only mild or moderate problems [^20]. The last three used the whole protein, not TB-500. None of these results is evidence for TB-500 [^6].","regulatory_status":"limbo","section_what_it_is":"TB-500 is a lab-made chain of seven amino acids [^6]. Amino acids are the building blocks of proteins. The chain copies a small part of thymosin beta-4, a protein the body makes, with one small chemical change at its start [^6] [^16]. Thymosin beta-4 has 43 amino acids, so TB-500 is a short piece of it [^6].\n\nTB-500 and thymosin beta-4 are not the same substance, even though many websites use the names as if they were [^6]. TB-500 is part of no FDA-approved drug and has no official quality standard [^6]. Websites promote it for injury recovery, tendons, muscles, wounds, hair growth and many other uses [^6]. Sport testing labs look for it because athletes and racehorses may be given it [^6] [^16].","section_is_it_legal":"TB-500 is in limbo: FDA lists it among the Category 2 substances whose nominations were withdrawn, and it has not added it to Category 1 [^1] [^2]. That is not approval, and it does not make compounding lawful. FDA reviewed it as a shot for wound healing, but websites promote it for injury recovery, muscle and much more [^5] [^6]. Checked 23 October 2026.\n\nCategory 2 is FDA's list of substances that may present significant safety risks. Category 1 is the list of substances pharmacies may use while FDA reviews them [^3]. The pharmacy that nominated TB-500 pulled its nomination, so it came off Category 2 [^1] [^6]. FDA then reviewed it on its own. FDA's scientists found no study of TB-500 in people and advised against adding it to the list [^6] [^8].\n\nOn 23 July 2026, FDA's Pharmacy Compounding Advisory Committee met on TB-500 [^4] [^5] [^7]. News and legal reports say it voted 8 to 6, with 1 member abstaining, to recommend adding TB-500 to the list [^11] [^12] [^21]. FDA's meeting page does not show the vote [^5]. A committee vote is only advice [^21]. FDA decides by writing a rule, after public comment [^12] [^22].\n\nUntil then, a pharmacy that makes TB-500 is outside federal law [^3] [^11]. Selling it for people to use is also illegal, even when the label says it is for research only [^9].","unofficial_channels":[{"type":"research-use-seller","what_it_is":"Sold online in vials with a label saying it is for research use only and not for people.","enforcement":[{"date":"2023-06-12","text":"FDA warning letter to an online seller that listed TB-500 among its unapproved new drugs.","source_url":"https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/warrior-labz-sarms-655280-06122023"},{"date":"2026-08-24","text":"FDA warning letter to an online seller of research-use peptide shots. The letter did not name TB-500.","source_url":"https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/peptide-partners-llc-735063-08242026"}],"legal_position":{"text":"FDA treats these products as unapproved new drugs when the seller's claims show they are meant for people, whatever the label says.","source_url":"https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/warrior-labz-sarms-655280-06122023"},"documented_risks":[{"text":"FDA warns that injected drugs bypass the body's defenses and can carry toxins or germs that cause sepsis.","source_url":"https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/warrior-labz-sarms-655280-06122023"},{"text":"A lab that tested TB-500 products sold online found their contents did not always match their descriptions.","source_url":"https://pubmed.ncbi.nlm.nih.gov/36482504/"}]},{"type":"compounding-outside-the-rules","what_it_is":"Made by a pharmacy from bulk TB-500 powder. Two websites say their TB-500 comes from a compounding pharmacy.","legal_position":{"text":"TB-500 has no official quality standard, is in no approved drug and is not on the federal list, so a pharmacy may not compound it under section 503A.","source_url":"https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act"},"documented_risks":[{"text":"FDA found no study of TB-500 in people by any route, so the safety of a compounded product is unknown.","source_url":"https://www.fda.gov/media/193349/download"},{"text":"FDA found that the public test sheets for TB-500 powder skip key checks, such as for clumps and germ toxins.","source_url":"https://www.fda.gov/media/193349/download"}]},{"type":"telehealth","what_it_is":"Websites where a person can book a visit to discuss using TB-500. They do not say how the TB-500 is obtained.","legal_position":{"text":"A prescription does not make TB-500 lawful to compound. It is still a substance that is not on the federal list.","source_url":"https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act"},"documented_risks":[{"text":"FDA found no human data on any product with TB-500, including whether it sets off the immune system.","source_url":"https://www.fda.gov/media/193349/download"}]}]},"provenance":{"name":{"fact_id":"24d10d8c-ce31-4537-b1d3-a2eba0bfbd43","source_url":"https://www.fda.gov/media/193349/download","source_type":"primary","captured_at":"2026-10-25T20:26:21.188Z","checked_at":"2026-10-25T23:50:29.995Z","confidence":1,"stale":false},"class":{"fact_id":"22b0325d-25dd-4348-ae82-17e5d004a693","source_url":"https://www.fda.gov/media/193349/download","source_type":"primary","captured_at":"2026-10-25T20:26:21.188Z","checked_at":"2026-10-25T23:50:29.983Z","confidence":1,"stale":false},"access":{"fact_id":"1cdec85b-0f33-433e-9cbe-207430d2f61c","source_url":"https://www.fda.gov/media/193349/download","source_type":"primary","captured_at":"2026-10-25T20:26:21.188Z","checked_at":"2026-10-25T23:50:29.959Z","confidence":1,"stale":false},"trials":{"fact_id":"9f1b3480-8f5c-4b7f-8888-773673b1972b","source_url":"https://clinicaltrials.gov/api/v2/studies?query.intr=Ac-LKKTETQ+OR+LKKTETQ&filter.overallStatus=RECRUITING%2CNOT_YET_RECRUITING&pageSize=50&sort=StartDate%3Adesc&countTotal=true&fields=NCTId%2CBriefTitle%2COverallStatus%2CPhase%2CLeadSponsorName%2CStartDate%2CLocationCountry%2CLocationState","source_type":"primary","captured_at":"2026-10-25T23:50:35.736Z","checked_at":"2026-10-25T23:50:35.736Z","confidence":1,"stale":false},"aliases":{"fact_id":"db0af7c3-22ea-41ae-b225-914e319fd315","source_url":"https://www.fda.gov/media/193349/download","source_type":"primary","captured_at":"2026-10-25T20:26:21.188Z","checked_at":"2026-10-25T23:50:29.981Z","confidence":1,"stale":false},"summary":{"fact_id":"45a3afe7-3f80-4b31-8e44-13dd9a150b0f","source_url":"https://www.fda.gov/media/193349/download","source_type":"primary","captured_at":"2026-10-25T20:26:21.188Z","checked_at":"2026-10-25T23:50:29.985Z","confidence":1,"stale":false},"citations":{"fact_id":"faa41007-89c0-442b-9b38-1192bf72296c","source_url":"https://www.fda.gov/media/193349/download","source_type":"primary","captured_at":"2026-10-25T20:26:21.188Z","checked_at":"2026-10-25T23:50:30.004Z","confidence":1,"stale":false},"known_risks":{"fact_id":"7f896896-e84f-4cce-b912-6e47fe77d39e","source_url":"https://www.fda.gov/media/193349/download","source_type":"primary","captured_at":"2026-10-25T20:26:21.188Z","checked_at":"2026-10-25T23:50:29.992Z","confidence":1,"stale":false},"short_answer":{"fact_id":"3d7cfb2a-e9d7-41ef-92b3-11fdc179367b","source_url":"https://peptideindex.ai/methodology#short-answer","source_type":"reference","captured_at":"2026-10-25T00:14:44.418Z","checked_at":"2026-10-25T23:50:29.987Z","confidence":1,"stale":false,"label":"our 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peptide policy and its warning letters to peptide sellers","url":"https://www.sheppard.com/insights/blogs/fda-balances-peptide-policy-with-enforcement-against-unlawful-peptide-sellers"},{"n":17,"title":"Lab analysis of mislabeled and impure TB500 products sold online, 2023","url":"https://pubmed.ncbi.nlm.nih.gov/36482504/"}],"section_evidence":[{"n":6,"title":"FDA briefing document on TB-500 for the July 2026 committee meeting, 15 May 2026","url":"https://www.fda.gov/media/193349/download"},{"n":14,"title":"TB-500 and BPC-157 on Achilles tendon healing in rats, 2026","url":"https://pubmed.ncbi.nlm.nih.gov/42542926/"},{"n":15,"title":"Thymosin beta-4 and a seven-amino-acid piece of it on skin wounds in diabetic and aged mice, 2003","url":"https://pubmed.ncbi.nlm.nih.gov/12581423/"},{"n":18,"title":"Review: full-length thymosin beta-4 and skin healing in animals and patients, 2012","url":"https://pubmed.ncbi.nlm.nih.gov/23050815/"},{"n":19,"title":"Thymosin beta-4 eye drops for severe dry eye: a small randomized trial, 2015","url":"https://pubmed.ncbi.nlm.nih.gov/25826322/"},{"n":20,"title":"First test of full-length thymosin beta-4 in healthy volunteers, 2021","url":"https://pubmed.ncbi.nlm.nih.gov/34346165/"}],"section_what_it_is":[{"n":6,"title":"FDA briefing document on TB-500 for the July 2026 committee meeting, 15 May 2026","url":"https://www.fda.gov/media/193349/download"},{"n":16,"title":"Identifying the thymosin beta-4 fragment in TB-500 for sport testing, 2012","url":"https://pubmed.ncbi.nlm.nih.gov/22962027/"}],"section_is_it_legal":[{"n":1,"title":"FDA: bulk drug substances that may present significant safety risks, including those withdrawn from Category 2","url":"https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks"},{"n":2,"title":"FDA: bulk drug substances nominated under section 503A, list updated 14 May 2026","url":"https://www.fda.gov/media/94155/download"},{"n":5,"title":"FDA: Pharmacy Compounding Advisory Committee meeting, 23 and 24 July 2026","url":"https://www.fda.gov/advisory-committees/advisory-committee-calendar/july-23-24-2026-meeting-pharmacy-compounding-advisory-committee-07232026"},{"n":6,"title":"FDA briefing document on TB-500 for the July 2026 committee meeting, 15 May 2026","url":"https://www.fda.gov/media/193349/download"},{"n":3,"title":"FDA: bulk drug substances used in compounding under section 503A","url":"https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act"},{"n":8,"title":"FDA: presentations to the committee on 23 July 2026, including TB-500","url":"https://www.fda.gov/media/193773/download"},{"n":4,"title":"Federal Register: notice of the July 2026 Pharmacy Compounding Advisory Committee meeting","url":"https://www.federalregister.gov/documents/full_text/html/2026/04/16/2026-07361.html"},{"n":7,"title":"FDA: questions put to the committee at the July 2026 meeting","url":"https://www.fda.gov/media/193711/download"},{"n":11,"title":"McDermott Will & Schulte: what the July 2026 committee votes on peptides mean","url":"https://www.mcdermottlaw.com/insights/bulk-list-bound-pcac-backs-majority-of-peptides-in-two-day-public-meeting/"},{"n":12,"title":"FDA Law Blog: the committee recommends four peptides for the 503A list","url":"https://www.thefdalawblog.com/2026/07/peptide-l-wave-pcac-approves-four-bulk-drug-substances-for-the-503a-list/"},{"n":21,"title":"NBC News: FDA panel recommends easing peptide limits despite agency scientists","url":"https://www.nbcnews.com/health/health-news/peptides-restrictions-ease-fda-panel-recommend-bpc-157-scientists-rcna588879"},{"n":22,"title":"NPR: FDA advisers back easing limits on six peptides, 23 July 2026","url":"https://www.npr.org/2026/07/23/nx-s1-5903202/fda-peptides-restrictions"},{"n":9,"title":"FDA warning letter to an online seller that listed TB-500, 12 June 2023","url":"https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/warrior-labz-sarms-655280-06122023"}]},"channelsOpener":"This section describes what happens and is not a recommendation.","sources":["https://clinicaltrials.gov/api/v2/studies?query.intr=Ac-LKKTETQ+OR+LKKTETQ&filter.overallStatus=RECRUITING%2CNOT_YET_RECRUITING&pageSize=50&sort=StartDate%3Adesc&countTotal=true&fields=NCTId%2CBriefTitle%2COverallStatus%2CPhase%2CLeadSponsorName%2CStartDate%2CLocationCountry%2CLocationState","https://peptideindex.ai/methodology#evidence-grade","https://peptideindex.ai/methodology#short-answer","https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks","https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/warrior-labz-sarms-655280-06122023","https://www.fda.gov/media/193349/download","https://www.fda.gov/media/94155/download"],"verified_at":"2026-10-25T23:50:30.004Z","published_at":"2026-10-26T00:03:16.026Z","parent":null,"children":[],"snapshots":{"trials":{"snapshot_at":"2026-10-25T23:50:35.736Z","stale":false,"notice":"A listing is not a recommendation. Trials have strict eligibility rules. Talk to your doctor and read the official record."}}}