TB-500 Dosage: The Protocols and the Arithmetic
The referenced protocols
| Phase | Common amount | Frequency | Duration |
|---|---|---|---|
| Loading | 2–2.5 mg | 2× weekly | 4–6 weeks |
| Maintenance | 2 mg | Every 1–2 weeks | Ongoing as needed |
The two-phase structure rests on a saturation argument: build tissue levels first, then top up less often. It is a coherent hypothesis. No trial has tested it, no trial has compared loading against a flat dose, and no trial has established that either produces a clinical result in a person.
Why milligrams, not micrograms
TB-500 protocols use amounts roughly a thousand times larger than BPC-157 protocols. That is not an error and it is worth internalizing before touching a syringe:
| Compound | Typical single dose | In micrograms |
|---|---|---|
| BPC-157 | 250–500 mcg | 250–500 |
| TB-500 | 2–2.5 mg | 2,000–2,500 |
Reconstitution and syringe units
Because doses are large, TB-500 has the opposite measurement problem to BPC-157: draws can approach or exceed the capacity of a U-100 insulin syringe.
| Vial | Water | Concentration | 2 mg dose | 2.5 mg dose | Doses per vial (2 mg) |
|---|---|---|---|---|---|
| 5 mg | 1 ml | 5 mg/ml | 40 units | 50 units | 2.5 |
| 5 mg | 2 ml | 2.5 mg/ml | 80 units | 100 units | 2.5 |
| 5 mg | 2.5 ml | 2 mg/ml | 100 units | over 1 ml | 2.5 |
| 10 mg | 2 ml | 5 mg/ml | 40 units | 50 units | 5 |
| 10 mg | 3 ml | 3.33 mg/ml | 60 units | 75 units | 5 |
| 10 mg | 5 ml | 2 mg/ml | 100 units | over 1 ml | 5 |
Note the rows where a 2.5 mg dose exceeds one millilitre — a U-100 syringe holds 100 units, so that draw does not fit and would need splitting or a more concentrated solution. Reconstituting TB-500 too generously creates this problem rather than solving one, which is the reverse of the advice that applies to microgram-dosed compounds.
Formula: concentration = peptide (mcg) ÷ water (ml). Volume = dose ÷ concentration. One unit on a U-100 insulin syringe = 0.01 ml. Values are for laboratory reference only.
Injection site
Protocols generally treat TB-500 as systemic, so site selection is a matter of convenience rather than targeting. The reasoning is that thymosin β4 circulates and acts on distant tissue — which is drawn from the parent-protein literature rather than from any study of the fragment. No head-to-head comparison of local against systemic administration has been published for either.
What is genuinely unknown
- Whether the fragment behaves like the parent protein. The loading rationale, the systemic-action rationale and the healing claims all originate in thymosin β4 research. TB-500 is a synthetic fragment of it, and this substitution is the most common error in the category.
- The effective human dose. No dose-finding study.
- Whether loading does anything. Untested.
- Long-term safety. No human safety database.
- A Phase 1/2 trial of the fragment was registered in February 2026 and has not reported. Registration is not evidence.
TB-500 — 5 mg / 10 mg — American Peptides
At milligram dosing, vial size determines how many doses you get and whether your draw fits a standard insulin syringe. A 10 mg vial gives five 2 mg doses; a 5 mg vial gives two and a half.
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Frequently asked questions
What is the standard TB-500 dosage?
No trial has established one. Protocols in circulation use a loading-then-maintenance structure: roughly 2–2.5 mg twice weekly for four to six weeks, then about 2 mg every one to two weeks. Those figures are practice-derived and are not supported by any human dose-finding study.
How many units is 2 mg of TB-500?
It depends on the water added. A 5 mg vial in 2 ml gives 2.5 mg/ml, so a 2 mg dose is 0.8 ml — 80 units on a U-100 insulin syringe, which is most of the barrel. Using 10 mg in 2 ml gives 5 mg/ml, and the same dose becomes 40 units.
Why are TB-500 doses in milligrams when BPC-157 is in micrograms?
Different compounds, roughly a thousandfold difference in the amounts protocols use. A 2 mg TB-500 dose is 2,000 mcg — about eight times a 250 mcg BPC-157 dose. This is the source of the most expensive mistake in blend vials, where the two are mixed and people apply the wrong scale.
Does TB-500 need to be injected at the injury site?
The protocols in circulation generally do not require it. TB-500 is described as acting systemically rather than depending on local concentration, which is the practical argument for site-independent injection. No study has compared local against systemic administration for the same injury.
Is there any trial behind the loading phase?
No. The loading-then-maintenance structure rests on the idea that tissue saturation matters early and less thereafter. That is a reasonable pharmacological hypothesis and it has never been tested in a human trial of TB-500.
Sources
- Goldstein AL, Hannappel E, Kleinman HK. Thymosin β4: actin-sequestering protein moonlights to repair injured tissues. Trends in Molecular Medicine, 2005;11(9):421–9. PubMed
- Philp D, Kleinman HK. Animal studies with thymosin β4, a multifunctional tissue repair and regeneration peptide. Annals of the New York Academy of Sciences, 2010;1194:81–6. PubMed
- Mendias CL et al. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. Sports Medicine, 2026. PubMed
- Registered but not yet reported: Phase 1/2 trial of the TB-500 fragment, NCT07487363.
- World Anti-Doping Agency. Prohibited List 2026, section S2.3 — thymosin-β4 derivatives including TB-500. WADA Prohibited List
Related guides
- TB-500: the parent protein versus the fragment
- BPC-157 dosage
- BPC-157 + TB-500 blend: the dose-halving trap
- How to reconstitute peptides
- Peptide reconstitution calculator