TB-500Dosage, Side Effects & Legal Status
TB-500 is sold as a synthetic fragment of thymosin beta-4, a naturally occurring protein involved in cell migration and wound repair. Most of the published wound-healing evidence is for full-length thymosin beta-4, not the shortened TB-500 fragment specifically, which is an important distinction vendors rarely make.
Reviewed by the PepGuard team · Last reviewed Jul 28, 2026
Synthetic fragment of Thymosin Beta-4 (actin-binding region) · also sold as Thymosin Beta-4 fragment, TB4 fragment 17-23
Photo: Abdulai Sayni / UnsplashWhat the literature and self-reports actually say.
| What's cited | Range |
|---|---|
| Commonly cited loading dose | 2-2.5 mg, twice weekly |
| Commonly cited loading phase length | 4-6 weeks |
| Commonly cited maintenance dose | 2-2.5 mg, once weekly |
| Commonly cited weekly total | 2-5 mg/week across sources |
No human trial has established a validated dose for TB-500 specifically. The figures below are what's most frequently cited in non-clinical and vendor-reported protocols, presented for informational comparison only, not as a recommendation. The calculator further down this page converts the loading or maintenance dose above into an exact draw volume for your vial size.
Signal strength, not just a list.
How often each effect shows up in the available sources, and how solid that evidence actually is.
| Signal | Frequency | Context |
|---|---|---|
| Injection site reaction | commonly reported | General to subcutaneous/intramuscular injection, not unique to TB-500. |
| Fatigue or lethargy | occasionally reported | Anecdotal self-reports only; not measured in a controlled TB-500 human trial. |
| Headache or flushing shortly after injection | occasionally reported | Anecdotal; no dose-response data exists for TB-500 specifically. |
| Effects on cancer risk or cell proliferation regulation | unknown / not studied | Actin-binding peptides that promote cell migration are a theoretical area of caution raised in review literature; not established as a risk in humans, not ruled out either. |
Not FDA-approved. Unapproved research compound.
TB-500 has never been approved by the FDA for human use. Full-length thymosin beta-4 has been studied in human trials for an unrelated ophthalmic indication under a separate regulatory track, but that does not extend to TB-500 as sold by research-peptide vendors. Its compounding bulk-substance status is subject to the same kind of periodic FDA review as BPC-157, so treat any "it's fine, it's legal" claim as time-stamped, not permanent.
Every claim above, traced back.
Primary studies, reviews, regulatory pages, and trial registries. Click through and check them yourself.
TB-500 questions, answered.
No, not exactly. TB-500 is sold as a shortened synthetic fragment of the full thymosin beta-4 protein. Most of the peer-reviewed wound-healing evidence was produced on the full-length protein, not the fragment sold as TB-500, so applying that evidence to TB-500 is an extrapolation, not a direct finding.
It hasn't been studied in a controlled human trial under that name. What exists is animal and cell-culture evidence for the parent protein, plus anecdotal self-reports for the fragment. That's a meaningfully thinner evidence base than a lot of marketing copy implies.
It's sold in the US as a "research use only" chemical, not as an approved drug or supplement for human use. Its status on the FDA's compounding bulk-substance list is reviewed periodically and has shifted before, so check current status rather than relying on an older claim.
TB-500 is typically sold as a lyophilized powder that needs to be reconstituted with bacteriostatic water before it can be drawn into a syringe. The calculator on this page turns a vial size, water volume, and target dose (like the loading or maintenance figures above) into an exact draw volume and syringe unit reading, it does the arithmetic only, not a recommendation on which dose to use.
Keep researching.
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