Healing / recovery

TB-500

Prepared by the ezGLP team. Sources last checked September 5, 2026. Profile reviewed September 9, 2026.

Also known as Thymosin Beta-4, TB4

Routes represented in the knowledgebase: Subcutaneous (SubQ).

Educational overview

TB-500 is listed in the ezGLP knowledgebase under Healing / recovery. Evidence and regulatory status can vary by formulation, route, and jurisdiction.

TB-500 is a synthetic peptide fragment of thymosin beta-4 (Tβ4), a 43-amino-acid actin-sequestering protein present in nearly all human cells and abundant in wound fluid and platelets. The commercial product usually corresponds to the actin-binding segment of Tβ4 (residues 17 to 23, LKKTETQ), sometimes with an added N-terminal acetyl group, rather than the full-length protein. Its class is best described as a research peptide marketed for tissue repair. Full-length Tβ4 has been shown in cell and animal work to promote cell migration, angiogenesis, and reduced inflammation and scarring, and a 2010 FASEB Journal study mapped those activities to specific peptide sequences including this fragment.

Evidence for TB-500 itself is thin and indirect. Almost all mechanistic and healing data concern full-length thymosin beta-4: rodent and animal wound-healing studies since 1999, cardiac repair models, and a small number of sponsored human trials of Tβ4 formulations in dermal wounds and eye disease. The fragment has been studied mainly in racehorses and in anti-doping laboratories, where its metabolism, detection limits, and metabolites have been characterized. A 2024 Journal of Chromatography B paper screened TB-500 metabolites for wound-healing activity and raised a prodrug hypothesis. No human clinical trial of TB-500 has been published, and the FDA has not identified any human exposure data for it.

TB-500 is not an approved medicine in any jurisdiction, and full-length thymosin beta-4 also remains investigational. In 2023 the FDA placed both thymosin beta-4 and the TB-500 fragment on its list of bulk drug substances that may present significant safety risks when compounded, citing immunogenicity and impurity concerns. In sport, the WADA Prohibited List names thymosin beta-4 and its derivatives, with TB-500 given as the example, under S2 peptide hormones and growth factors, prohibited at all times; racing authorities have banned it in horses since the early 2010s. Products sold as TB-500 are research-grade material or unapproved compounded injections.

TB-500 is supplied as a lyophilized powder in a vial that is reconstituted before subcutaneous or intramuscular injection. No human pharmacokinetic study of the fragment has been published, so any half-life figure attached to it is an estimate rather than a measured value, and storage and beyond-use time follow the product or pharmacy label. A dose log for TB-500 commonly records vial lot, reconstitution date, concentration, route, injection site, and any reaction, which are the details relevant to an adverse-event report or an anti-doping inquiry. An inventory record tied to lot numbers is useful because identity and purity of research-grade material are not independently verified.

Category: Healing / recovery
Routes represented: Subcutaneous (SubQ)
Approximate library half-life: 1.5 hours; formulation-dependent and not dosing guidance
Storage context: Follow the dispensed product or pharmacy label; storage and beyond-use time vary by formulation.

Published literature

Safety evidence

Serious or important: potential immunogenicity, aggregation, impurity, or product-quality risks.

A dependable route-specific human interaction and side-effect profile is not established; this is not evidence of no risk.

Safety evidence source

Interaction evidence

These are general, pairwise evidence notes. Green identifies the potential-synergy category, while Lv3/Lv2/Lv1 communicates evidence strength; it does not guarantee benefit or cancel a safety warning.

With BPC-157

Complementary evidenceLv2

An exploratory rat Achilles-tendon study found improved histology versus control for the combination, but no additional benefit over either peptide alone.

Interaction evidence sourceFDA TB-500 assessment

With GHK-Cu

Complementary evidenceLv1

The pair is proposed as complementary from separate evidence involving thymosin-beta-4-related cell migration and GHK-Cu-associated matrix accumulation.

Interaction evidence sourceGHK-Cu wound studyFDA TB-500 assessment

With KPV

Complementary evidenceLv1

The pair is proposed as complementary through separate preclinical rationales involving tissue migration, remodeling, and inflammatory signaling.

Interaction evidence sourceKPV preclinical studyFDA KPV assessment

Common questions

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

Not exactly. Thymosin beta-4 is a 43-amino-acid protein found in almost all human cells. TB-500 is a short synthetic fragment corresponding to its actin-binding region, typically residues 17 to 23, sometimes acetylated. Most healing and angiogenesis research used the full-length protein, and the FDA lists the two separately. Findings for thymosin beta-4 cannot be assumed to apply to the fragment, which has no published human trial.

Is TB-500 banned by WADA?

Yes. The WADA Prohibited List names thymosin beta-4 and its derivatives, giving TB-500 as the example, under S2 peptide hormones, growth factors, and related substances. It is prohibited at all times, in and out of competition. Anti-doping laboratories have published detection methods for TB-500 and its metabolites in urine and plasma since 2012, and horse-racing regulators banned the substance in equine sport around the same time.

Has TB-500 been tested in humans?

No published human clinical trial of TB-500 exists. Human data concern full-length thymosin beta-4, which a sponsor has studied in small trials for dermal wounds and eye conditions, and none of those products has been approved. The FDA stated in 2023 that it had not identified any human exposure data for compounded TB-500, and reports of effects in people are anecdotal or come from doping-control case work.

Is TB-500 FDA approved?

No. Neither TB-500 nor thymosin beta-4 is approved for any indication. In 2023 the FDA placed both on its list of bulk drug substances that may present significant safety risks when compounded, citing immunogenicity, aggregation, peptide-related impurities, and an absence of safety information. That listing removes them from routine compounding under section 503A, so any injectable sold as TB-500 in the United States is unapproved.