There is no clinically validated human dose you can look up here, because for this compound one does not exist in the way regulated drugs have. We report what research and regulators actually say, and nothing more.
What it is
TB-500 is a synthetic peptide modeled on the actin-binding region (the LKKTETQ motif) of thymosin beta-4, a naturally occurring repair protein found in nearly every human cell and concentrated at wound sites. The research-chemical version is a fragment, not the full parent protein.
The evidence, stated plainly
As of mid-2026 there are no completed published randomized controlled trials of TB-500 (the fragment) in humans. The strongest evidence is animal work on the full thymosin beta-4 protein, plus narrow early human trials of that parent protein for indications like dry eye. It is important to note the distinction: TB-500 the fragment and thymosin beta-4 the drug candidate are not the same regulatory or evidence object.
Evidence is largely preclinical (animal/in-vitro). We label evidence by its strongest honest tier, never by a vendor’s enthusiasm.
Half-life & timing
No published human pharmacokinetic study has directly measured TB-500 plasma half-life. Estimates of several hours to days are extrapolated from molecular weight and peptide class, not measured in people.
Regulatory status
Not FDA-approved for any indication. Following a February 2026 reclassification, TB-500 (as a thymosin beta-4 fragment) is a 503A Category 2 bulk drug substance, prohibited in compounding. It is banned at all times in sport under WADA Section S2.
Storage & handling
As with most peptides: lyophilized powder stored cold (2 to 8 C, or -20 C for longer), reconstituted solution kept at 2 to 8 C in bacteriostatic water and used within about 28 days, never frozen once mixed. Independent testing of vendor TB-500 has shown variability in actual peptide content, purity, and contamination.
Whatever dose a protocol or provider gave you, converting it to syringe units is where errors turn into 10× mistakes. Our calculator does only that conversion — it never invents the dose.
Open the reconstitution calculatorThe honest bottom line
The parent protein thymosin beta-4 has a genuinely promising preclinical record and some early human trials. The research-chemical fragment sold as "TB-500" is unapproved, unstandardized, has no measured human half-life, and has not been validated in controlled human trials. Treat marketing that blurs the two with suspicion.
Sources
- Systematic/evidence reviews of thymosin beta-4 and TB-500, 2026.
- FDA 503A reclassification of thymosin beta-4-related substances, Feb 2026.
- WADA 2026 Prohibited List, Section S2.
- FormBlends/PubMed evidence grading: no direct human PK for TB-500.
- Reports on RGN-259 (topical Tβ4) clinical program.
Sourcing reflects literature available at publication and may change. See How We Rate Evidence.