TB-500 | Reviews, Clinical Trials, and Safety

TB-500 is a research peptide being studied for its wound healing and regenerative effects.

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    Compound Overview

    Class of Compound:


    Mechanism of Action:

    TB-500 upregulates the cell-building protein actin, a key component of cell structure and movement, while blocking actin polymerization. It has also been shown to promote angiogenesis, likely through the Notch signaling pathway.

    Notable Studies:

    Also Known As:

    Thymosin beta-4, timbetasin

    Research Applications:

    • Wound healing
    • Inflammation
    • Injury recovery
    • General anti-aging research


    • Prohibited by WADA
    • Limited clinical studies
    • No FDA review or approval

    Chemical Structure

    TB-500 chemical structure

    What is TB-500?

    TB-500 is the synthetic version of a natural compound called thymosin-beta-4. It is a research chemical that has been used in both test-tube and animal studies, along with a small number of human trials, having been found to promote wound healing, muscle repair, joint and tissue strength, and endothelial health.

    Thymosin-beta 4 was first identified in 1981 after being isolated from a bovine thymus gland sample [1]. In the early-2010’s, the synthetic version TB-500, which had been developed for veterinary purposes, was rumored to be rampantly used in competitive horse racing — giving horses receiving it a significant competitive edge against other horses. It was at this time that testing measures to detect TB-500 in race horses began to be developed in earnest [2].

    TB-500, Thymosin beta-4, and all other derivatives thereof are now banned from competitive horse racing, as well as all sporting competitions subject to the Code of the World Anti-Doping Agency (WADA) [3].

    However, research on TB-500 is certainly ongoing, and the peptide is of particular interest for researchers studying anti-aging, wound healing, inflammation, cardiovascular health, among other diverse applications.

    Our research guide to TB-500 can be found below, including its potential benefits, known side effects, and other pertinent information about the research chemical.


    What Does TB-500 Do?

    TB-500 is a synthetic version of thymosin-beta 4, a peptide (short chain of amino acids) that has been found in most cells in animals and humans. It is a chain of 42 amino acids (a “tritetraconpeptide”) in the following structure:


    It is also known as timbetasin, and has a chemical structure of C212H350N56O78S and a low molecular weight [4].

    The primary function of thymosin beta-4 is in cell repair and regeneration. It exhibits most of its actions through the sequestering of actin, which — in the simplest of terms — means that it keeps actin in place. In the event of an injury, thymosin beta-4 would sequester actin at the site of the injury, signaling a cascade of other reactions to occur.

    Because actin is a key component of connective tissue, this actin-sequestering action of thymosin-beta 4 helps promote connective tissue healing and regeneration. This activity also signals for the body to begin migrating other stem or progenitor cells to the site where repair is needed. Thymosin beta 4 helps those cells to differentiate into, for example, myocytes (muscle cells), epithelial cells, or other connective or vascular cells to repair the area and rebuild the tissue [1, 5].

    TB-500 Benefits | Clinical Trials

    Much of the existing research on TB-500 and thymosin-beta 4 has been done in test-tube or animal studies. However, the results of these studies point to some potentially promising applications for muscle and connective tissue growth, as well as vascular function.

    Note that most of this research refers to the use of thymosin-beta 4, the organic and naturally occurring version of lab-made TB-500. However, TB-500 is structurally and chemically identical to thymosin-beta 4 and theoretically should have the same effects in research subjects.

    In some studies, TB-500 may be referred to as synthetic thymosin-beta 4.

    Here is a list of potential benefits:

    Muscle. One research area with great potential is the effects of TB-500 on muscle, but not just skeletal muscle. Thymosin-beta 4 appears to exert promising positive effects on both skeletal muscle and cardiac (heart) muscle.

    In one 6-month mouse study, researchers found that thymosin-beta 4 administration improved skeletal muscle fiber regeneration in mice who were deficient in dystrophin, a connective tissue protein [6].

    It also may help to protect cardiac muscle and promote repair after damage to the heart through a number of mechanisms [7].

    Connective tissue. Because of its effects on body proteins, TB-500 may also provide some potential benefits for connective tissue like joints, tendons, and the collagen matrices that anchor the skin, muscles, and organs.

    In one animal study, researchers treated incision wounds on rats with thymosin-beta 4. They also kept an untreated control group to compare how the wounds healed differently. In the wounds treated with thymosin-beta 4, the researchers noted that there was minimal scarring present compared to the controls, and that the treated wounds were also much narrower in width.

    Upon closer inspection, they were able to determine that this was because the thymosin beta-4 treated wounds had more tightly organized collagen fibers that were more mature, while the controls had more disorganized arrangements of collagen fibers that appeared to be less mature.

    Thymosin-beta 4 administration appeared to significantly improve collagen structure and hasten its maturity, resulting in improved wound healing and reduced scarring [8].

    Vasculature and endothelial function. Vasculature refers to blood vessels, and the endothelium is the inner lining of each vessel that helps to regulate blood flow and blood pressure through constriction and dilation. Healthy blood vessels are flexible with highly functioning endothelial linings.

    Animal and test-tube models have indicated that thymosin beta-4 can help promote the growth and development of new blood vessels in a process known as neovascularization, but they can also help promote endothelial cell differentiation to help maintain or restore endothelial function in damaged vessels [9, 10].

    Other effects. Other animal studies point to even more potential applications for TB-500 and thymosin-beta 4. One mice study noted that thymosin-beta 4 administration helped to improve blood glucose control and increase insulin sensitivity in mice. Researchers also noted improvements in triglyceride levels with thymosin-beta 4 administration in this study [11].

    Thymosin beta-4 has also been used to promote hair growth in mice, so it also shows promise as a follicle stimulator for hair loss conditions [12].

    It is important to recall that all of this research is considered pre-clinical, and there hasn’t yet been a great deal of research in humans. Although test-tube and animal studies can reveal some of the potential effects of TB-500, it is important to note that these effects have not been confirmed in human subjects.

    Human trials. A handful of high-quality, randomized controlled trials have investigated the effects of thymosin beta-4 administration in humans.

    One studied venous ulcers, which are a result of poor circulation and typically manifest on the lower leg. With 73 participants in all, researchers found that a dose of 0.03% synthetic thymosin-beta 4 increased the rate of wound healing, and helped 25% of patients achieve full healing within 3 months [13].

    Another investigated the effects of thymosin-beta 4 eye drops for severe dry eye. Among nine participants, researchers found that — after 56 days of treatment — the treatment group had a 35% reduction in eye discomfort, 59% improvement in dry eye testing parameters and increased tear production [14].

    There has also been one trial in healthy adults to help assess the safety and potential side effects of thymosin-beta 4, and some early pilot and exploratory studies in regards to thymosin-beta 4 and cardiac function [15, 16].

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    TB-500 Side Effects

    On the whole, the research to date indicates that TB-500 exhibits minimal to no side effects when administered to research subjects at prudent doses.

    The results of one randomized controlled trial in 40 healthy adults - with the express purpose of assessing potential safety concerns with synthetic thymosin-beta 4 - were published in 2010. The researchers found that, in healthy adult subjects, intravenously-administered doses ranging from 42 to 1,260 mg of Tbeta4 appear to be well-tolerated and present minimal risk for toxicity [17]. (Note that the dosages for TB-500 would have been significantly smaller.)

    Although there were some adverse events in the course of the study, they were uncommon occurrences and were only mild or moderate in nature. It’s important to note that this was a carefully designed study using only healthy subjects.

    Regardless of these preliminary findings, TB-500 should be administered with the utmost caution — by qualified researchers only. Under no circumstances should it be self-administered for experimental or recreational purposes.

    Is TB-500 Safe?

    The peptide TB-500 has not been evaluated for safety by the United States Food and Drug Administration (FDA), nor by any of its international regulatory counterparts. Accordingly, any statements or findings - formal or otherwise - that TB-500 is “safe” must be taken with a grain of salt.

    Nonetheless, in published research to date, TB-500 administration has produced minimal side effects in animal and human studies alike [8, 14, 15, 17].

    Many peptides can product injection site pain, lightheadedness, nausea, or even flu-like symptoms in subjects. But there have been very limited reports of TB-500 causing even such minor side effects. On the contrary, it appears that TB-500 is very well tolerated among a range of subjects.

    As with any research involving peptides, however, due caution is required when administering TB-500 to test subjects.

    TB-500 Dosage Calculator

    Given the relative paucity of published research to date on TB-500, there are no set dosage recommendations for research purposes.

    Nonetheless, in the scientific and clinical studies to date, the most common reported dosing range of TB-500 has been 2-5 mg, administered twice weekly, for a duration of 4 to 8 weeks, depending on the nature of the research. Some clinicians favor a higher starting dose for the initial 1 to 2 weeks, followed by a maintenance dose equal to one half of the original dose for the 2 to 6 weeks thereafter.

    Alternatively, one human study used a thymosin-beta 4 dose of 0.03% in a gel for the treatment of venous ulcer wounds with favorable results [13].

    In research applications, it’s important to use the lowest effective dose, so it’s advisable to start with the lowest dose possible.


    Where to Buy TB-500 Online? | 2024 Edition

    For researchers looking to study TB-500, the peptide experts at Peptides.org recommend the following top-rated vendor:

    Limitless Life

    We are fans of Limitless Life due to their strong commitment to quality using independent laboratory testing, as well as their excellent customer reviews, flexible shipping options, and simple reship policy.

    Here’s a little bit more about why we like Limitless Life:

    • Independent Laboratory Testing: Limitless Life partners with independent third-party labs to ensure that each back of product manufactured in their facility meets strict quality and purity standards.
    • Accreditation and Customer Reviews: Limitless Life is the only peptide vendor that’s accredited by the Better Business Bureau, and they have outstanding reviews on third-party review sites.
    • Reliable Shipping: Limitless Life offers fast and flexible FedEx shipping for domestic orders, and they aim to have all international orders delivered within 5 days of shipping.
    • Easy Returns: Limitless Life offers a flexible return and reship policy for all researchers to ensure order satisfaction. They also offer inexpensive shipping insurance that covers damages or lost orders.
    • Science-Based Approach: Limitless Life’ website includes detailed summaries of the available research on each peptide they sell, including TB-500.
    • Fair Prices: Limitless Life also has some of the best prices for research peptides available.

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    Bacteriostatic Water and TB-500

    A lab need to be equipped with the necessities for safe and effective peptide research.

    To comply with expert guidelines of TB-500 handling, researchers need to have the right supplies at disposal.

    These include sterile vials, bac water, and more.

    Getting a hold of all the proper ancillary supplies can be challenging for even the most experienced researchers, as few trusted retailers carry what is required.

    But it is a necessary step for all researchers.


    TB-500. Just. Works.

    TB-500 is the synthetic version of thymosin-beta 4, a natural healing compound found in human and animal cells.

    Its main function is to sequester actin, which sets off a cascade of other reactions in the body aimed at healing, repair, and regeneration of damaged cells, tissues and blood vessels.

    Its potential benefits include muscle repair, strengthening of connective tissue, wound healing and improving endothelial function. It may also help with hair loss, dry eye, and insulin resistance. However, research is still in early phases, with little human studies available.

    TB-500 should only be used by professionals for research purposes, and the substance (along with exogenous natural thymosin beta-4) has been banned by WADA at all times for use in competitive athletics. It is also banned from competitive horse racing, as it has also seemed to give race horses who received it an unfair advantage.


    TB-500 shows a great deal of potential in the realms of tissue repair, heart health, and wound healing. We are looking forward to seeing the results of future trials on TB-500.

    We recommend buying TB-500 from a reputable source like Limitless Life due in part to their fair pricing, rigorous quality control processes, and solid reputation.


    1. Goldstein AL, Hannappel E, Sosne G, Kleinman HK. Thymosin β4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opin Biol Ther. 2012;12(1):37-51. doi:10.1517/14712598.2012.634793
    2. Ho EN, Kwok WH, Lau MY, 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. doi:10.1016/j.chroma.2012.09.043
    3. World Anti-Doping Agency. World Anti-Doping Code International Standard Prohibited List 2022. WADA website. January 1, 2022. Accessed Mar 2022. https://www.wada-ama.org/sites/default/files/resources/files/2022list_final_en.pdf
    4. National Center for Biotechnology Information. PubChem Compound Summary for CID 16132341, Thymosin beta4. https://pubchem.ncbi.nlm.nih.gov/compound/Thymosin-beta4. Accessed March 17, 2022.
    5. Irobi E, Aguda AH, Larsson M, et al. Structural basis of actin sequestration by thymosin-beta4: implications for WH2 proteins. EMBO J. 2004;23(18):3599-3608. doi:10.1038/sj.emboj.7600372
    6. Spurney CF, Cha HJ, Sali A, et al. Evaluation of skeletal and cardiac muscle function after chronic administration of thymosin beta-4 in the dystrophin deficient mouse. PLoS One. 2010;5(1):e8976. Published 2010 Jan 29. doi:10.1371/journal.pone.0008976
    7. Bjørklund G, Dadar M, Aaseth J, Chirumbolo S. Thymosin β4: A Multi-Faceted Tissue Repair Stimulating Protein in Heart Injury. Curr Med Chem. 2020;27(37):6294-6305. doi:10.2174/0929867326666190716125456
    8. Ehrlich HP, Hazard SW 3rd. Thymosin beta4 enhances repair by organizing connective tissue and preventing the appearance of myofibroblasts. Ann N Y Acad Sci. 2010;1194:118-124. doi:10.1111/j.1749-6632.2010.05483.x
    9. Trenkwalder T, Deindl E, Bongiovanni D, et al. Thymosin-β4-mediated therapeutic neovascularization: role of the PI3K/AKT pathway. Expert Opin Biol Ther. 2015;15 Suppl 1:S175-S185. doi:10.1517/14712598.2015.1011122
    10. Smart N, Risebro CA, Melville AA, et al. Thymosin beta4 induces adult epicardial progenitor mobilization and neovascularization. Nature. 2007;445(7124):177-182. doi:10.1038/nature05383
    11. Zhu J, Su LP, Ye L, Lee KO, Ma JH. Thymosin beta 4 ameliorates hyperglycemia and improves insulin resistance of KK Cg-Ay/J mouse. Diabetes Res Clin Pract. 2012;96(1):53-59. doi:10.1016/j.diabres.2011.12.009
    12. Dai B, Sha RN, Yuan JL, Liu DJ. Multiple potential roles of thymosin β4 in the growth and development of hair follicles. J Cell Mol Med. 2021;25(3):1350-1358. doi:10.1111/jcmm.16241
    13. Guarnera G, DeRosa A, Camerini R; 8 European sites. The effect of thymosin treatment of venous ulcers. Ann N Y Acad Sci. 2010;1194:207-212. doi:10.1111/j.1749-6632.2010.05490.x
    14. 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. doi:10.1097/ICO.0000000000000379
    15. Zhu J, Song J, Yu L, et al. Safety and efficacy of autologous thymosin β4 pre-treated endothelial progenitor cell transplantation in patients with acute ST segment elevation myocardial infarction: A pilot study. Cytotherapy. 2016;18(8):1037-1042. doi:10.1016/j.jcyt.2016.05.006
    16. Choudry FA, Yeo C, Mozid A, Martin JF, Mathur A. Increases in plasma Tβ4 after intracardiac cell therapy in chronic ischemic heart failure is associated with symptomatic improvement. Regen Med. 2015;10(4):403-410. doi:10.2217/rme.15.9
    17. Ruff D, Crockford D, Girardi G, Zhang Y. 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. doi:10.1111/j.1749-6632.2010.05474.x
    18. Racing Medication & Testing Consortium. Thymosin B4 bulletin. RMTC website. N.d. Accessed Jul 2021. http://rmtcnet.com/wp-content/uploads/2016/01/RMTC-TB-500-Drug-Bulletin.pdf