PEPTIDE COMPARISON

Thymosin Alpha-1 vs Thymosin Beta-4

Two distinct thymosin peptides with different biology, research programs, and sport status.

QUICK ANSWER

Thymosin Alpha-1 vs Thymosin Beta-4: the main difference.

The shared 'thymosin' name does not make these peptides functionally or clinically equivalent. Thymosin alpha-1 has the broader disease-oriented human literature; thymosin beta-4 has a repair-focused program and explicit WADA prohibition.

Decision field	Thymosin Alpha-1	Thymosin Beta-4
Primary biology	Immune modulation	Actin binding and repair biology
Human research	Trials and meta-analyses across selected diseases	Early phase systemic and topical studies
FDA status	No U.S.-approved product identified	No approved product identified
2026 WADA	Not specifically named	Prohibited at all times
Main interpretation risk	Generalizing across diseases	Conflating formulations and TB-500

SOURCES

Thymosin Alpha-1 vs Thymosin Beta-4 sources.

Human trial / 2025Thymosin alpha-1 for sepsis: multicenter randomized phase 3 trialPubMed Review / 2025Thymosin alpha-1 in sepsis: systematic review and meta-analysisPubMed WADA / 20262026 Prohibited ListWorld Anti-Doping Agency Human trial / 2021Phase 1 study of recombinant human thymosin beta-4PubMed Human trial / 2015Thymosin beta-4 ophthalmic solution in dry eyePubMed

Thymosin Alpha-1 vs Thymosin Beta-4: the main difference.

Thymosin Alpha-1 vs Thymosin Beta-4 sources.

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