Compare
TB-500 vs Thymosin Beta-4
The honest difference
TB-500 is a small man-made piece of thymosin beta-4, not the same thing. Only the whole protein has human trials, and those mostly disappointed.
Peptide
TB-500
Grade D: animal data only
Why people buy it
People buy it to recover faster from injuries and hard training. It is popular with gym-goers and athletes.
Bottom line
Sold on the back of animal studies and a different molecule. Not proven in people.
- UK status
- Not a licensed medicine and not approved by the MHRA for any use. There is no marketing authorisation for thymosin beta-4 or the TB-500 fragment.
- Sport / WADA
- Prohibited at all times (in and out of competition) under WADA class S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics).
Peptide
Thymosin Beta-4
Grade C: early / limited human data
Why people buy it
People buy it to heal injuries and recover faster from training. It is often sold next to TB-500, or as the 'full' version of it.
Bottom line
A real medicine candidate that has mostly disappointed in trials. For injuries and recovery, it is untested in people.
- UK status
- Not a licensed medicine in the UK. The MHRA has authorised no thymosin beta-4 product, and no thymosin beta-4 product (including RGN-259) has marketing authorisation anywhere.
- Sport / WADA
- Prohibited at all times (in and out of competition). The 2026 WADA Prohibited List names 'Thymosin-β4 and its derivatives e.g. TB-500' under S2.3 (Growth factors and growth factor modulators).
Grades are about evidence in humans, not about whether something is right for you. Nothing here is dosing advice. Talk to a qualified clinician before any health decision.
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