Peptide Guides
TB-500 Dosage: What the Fragment Is, and What the Numbers Rest On
TB-500 and thymosin beta-4 are used interchangeably in marketing and are not the same thing. That conflation is where most TB-500 dosing figures come from.
Peptide Library Editorial · March 27, 2026 · Updated August 30, 2026 · 3 min read
TB-500 is a synthetic fragment. Thymosin beta-4 is the full 43-amino-acid protein. They are used interchangeably in marketing and they are not the same molecule.
That distinction matters because essentially all the published research is on thymosin beta-4, while the product sold is the fragment. Dosing figures inherit an assumption that the two behave equivalently.
Not an approved drug. Neither TB-500 nor thymosin beta-4 has an approved human indication. TB-500 is sold for laboratory research only, and nothing here is dosing guidance.
Fragment versus protein
Thymosin beta-4 | TB-500 | |
|---|---|---|
What it is | Full naturally occurring protein | Synthetic partial sequence |
Length | 43 amino acids | Short active-region fragment |
Research base | Extensive preclinical, some clinical | Very little on the fragment itself |
What is sold | Rarely | Almost always |
The fragment corresponds to the actin-binding region, which is the rationale for expecting it to reproduce the relevant activity. That is a reasonable hypothesis. It is not the same as having been tested.
This is the same reasoning behind AOD-9604 — isolate the active region, discard the rest. In that case the hypothesis reached human trials and did not carry forward. For TB-500 it has not been tested at all.
What the research covers
The thymosin beta-4 literature centres on actin regulation, cell migration, and tissue repair, with work spanning cardiac, corneal, dermal, and more recently kidney contexts.
Actin sequestration. The established molecular function — binding G-actin and regulating cytoskeletal dynamics.
Cell migration. Central to wound repair, and the basis for most therapeutic interest.
Angiogenesis and inflammation. Reported effects in preclinical models.
Human dose-ranging for the fragment. Absent.
Why it is paired with BPC-157
The two are almost always discussed together and frequently sold blended. The rationale is complementary mechanisms — different proposed pathways, similar proposed outcomes.
The BPC-157 and TB-500 guide covers the blend labelling trap in detail, and the GLOW and KLOW blends both include TB-500 at 10 mg.
The vial math
TB-500 is discussed at milligram scale rather than micrograms, which changes the arithmetic compared with most research peptides.
Vial | BAC water | Concentration | 2 mg | 2.5 mg | 5 mg |
|---|---|---|---|---|---|
10 mg | 2 mL | 5 mg/mL | 40 units | 50 units | 100 units |
10 mg | 3 mL | 3.33 mg/mL | 60 units | 75 units | Over one barrel |
5 mg | 2 mL | 2.5 mg/mL | 80 units | 100 units | Whole vial |
Milligram-scale targets push against the 100-unit barrel limit quickly, which is a reason to use less diluent rather than split draws. The peptide calculator handles any combination.
Storage
Storage is the same as any reconstituted vial: 2–8 °C, protected from light, never frozen, and bounded by the shorter of peptide stability and the 28-day limit on bacteriostatic water. The bacteriostatic water guide covers the detail.
Frequently asked questions
Is TB-500 the same as thymosin beta-4?
No. TB-500 is a synthetic fragment; thymosin beta-4 is the full protein. The research is mostly on the latter.
Where do TB-500 dosing figures come from?
Extrapolation from animal work on thymosin beta-4, carried across to the fragment. No human dose-ranging study of TB-500 establishes them.
Is it banned in sport?
Yes. TB-500 is prohibited under anti-doping rules.
Research and educational use only. Peptide Library is an independent research and comparison platform and does not sell peptides. Nothing here is medical advice, dosing guidance, or a recommendation to administer any substance to a person or an animal. Consult a licensed clinician for anything concerning human health.
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Editorial content from Peptide Library. Research and educational use only. Not medical advice.
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