Is thymosin alpha 1 the same as TB-500?

No. They are different molecules from different parent peptides. Thymosin alpha-1 (thymalfasin, Zadaxin) is an immune-modulating thymic peptide, molecular weight 3,108 daltons, with a 98-person hepatitis B trial and the 1,106-person TESTS sepsis trial. TB-500 is the N-acetylated thymosin beta-4 fragment 17 to 23, sequence Ac-LKKTETQ, molecular weight 889.01 daltons for the free base. FDA's 2026 review found no published study giving TB-500 to a person. Sharing the word thymosin is not a shared molecule and not a shared evidence record. This site does not rank them. Full records at /compounds/thymosin-alpha-1 and /compounds/tb-500.

Educational use only. This database summarizes published research and is not medical advice. Where a dose appears it is a record of what a trial or clinic ran, or what people describe doing, with its source attached. Nothing here is a recommendation for personal use.

Part of immune and longevity peptides. Thymosin alpha-1, thymalin, epitalon, MOTS-c, humanin, and the bioregulator family.