What it is
TB-500 is a synthetic fragment related to thymosin beta-4 (TB4), a naturally occurring protein involved in cell repair. A key nuance often glossed over: most published research is on the full TB4 protein, while what's sold online is a small synthetic piece of it — and a fragment doesn't automatically share the whole protein's effects or safety.
The claims
It's promoted for wound healing, reduced inflammation, and tissue regeneration. A scoping review notes biologic plausibility across several repair-related pathways — but plausibility is a starting point, not proof of clinical benefit.
The evidence
The honest summary from the literature: there are essentially no human clinical trials on TB-500 itself. A 2026 scoping review concluded the mapped literature does not establish clinical efficacy, optimal dosing, route of administration, product equivalence, or long-term safety for musculoskeletal uses. Some sources note small cohorts describing it as well-tolerated, but no large or long-term safety studies exist.
Safety
Its safety in humans is effectively unknown. “Well-tolerated in a handful of people” is not the same as an established safety profile, and the fragment-vs-whole-protein distinction adds further uncertainty. Long-term effects have not been characterized.
Regulatory status
FDA Category 2 bulk drug substance (safety concerns; not for compounding); WADA-prohibited; not approved for human use. Sold online as a research chemical.
FAQ
Not exactly — it's a synthetic fragment associated with TB4. Research on the full protein shouldn't be assumed to transfer to the fragment sold online.
Those reports come from small, uncontrolled use. Absence of reported harm in a few people is not demonstrated safety, especially long-term.
No — it's on the WADA Prohibited List. Testing positive carries sanctions.
Sources
This profile summarizes the following. Follow the links to read the originals — and remember that summaries age, so check for newer information.
- Thymosin Beta-4 and TB-500 in tissue healing & musculoskeletal repair: a scoping review (MDPI)
- TB-500: status, risks, and bans in sport and military (BSCG)
- TB4 and TB-500 peptide therapy: what to know (Innerbody)
Inclusion here is not endorsement of any source's claims; several are cited so you can compare how different outlets characterize the same evidence.
Reviewed by Jules — part of the PepConnection crew.