Comparison · Updated
Epithalon VS Thymosin Alpha-1
Short answer
Thymosin Alpha-1 has stronger published evidence than Epithalon: tier A (Controlled human trials) vs tier B (Small human studies).
Neither Epithalon nor Thymosin Alpha-1 is FDA-approved.
Epithalon is prohibited in sport by WADA under section S0; Thymosin Alpha-1 is not on the WADA Prohibited List.
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Side by side
| Field | Epithalon | Thymosin Alpha-1 |
|---|---|---|
| Evidence tier | B Tier B · Small human studies | A Tier A · Controlled human trials |
| Tier rationale | Human data are limited to small biomarker studies and an older controlled study in retinitis pigmentosa, almost all from one research group; no randomized trial exists. Most evidence is cell and animal work. | Many randomized trials, including the phase 3 TESTS trial in sepsis (BMJ 2025, no mortality benefit shown) and earlier RCTs in chronic hepatitis B. It is approved outside the US and EU but not by the FDA or EMA. |
| FDA status | Not approved | Not approved |
| Other approvals | None listed |
|
| WADA | Prohibited · S0Non-approved substances | Not on the Prohibited List |
| Family | Longevity & Immune | Longevity & Immune |
| Residues | 4amino acids | 28amino acids |
| Molecular weight | 390.4 Da | 3,108.3 Da |
| Formula | C14H22N4O9 | C129H215N33O55 |
| Discovered | Not on file | Not on file |
| Routes studied | Subcutaneous, Intramuscular | Subcutaneous, Intramuscular |
| Mechanism | In cultured human fibroblasts, Epithalon (Ala-Glu-Asp-Gly) was reported to induce expression of the telomerase catalytic subunit (hTERT), telomerase activity and telomere elongation. It is also proposed to stimulate pineal melatonin production and restore circadian neuroendocrine function. | Thymosin alpha-1 is a 28-amino-acid thymic peptide that activates toll-like receptors (TLR2, TLR9) on dendritic cells, promoting MHC class I expression and antigen presentation. It enhances CD4+ and CD8+ T-cell maturation, stimulates NK cell cytotoxicity, and shifts the immune balance toward a Th1 response, improving antiviral and antitumor immunity. |
| Safety notes | Human safety data are limited to small studies from the Khavinson group; no long-term controlled safety data exist. | Approved outside the US/EU (Zadaxin) with clinical safety data from hepatitis trials; in the 1,106-patient TESTS sepsis RCT no safety outcome differed from placebo. |
| Cited studies | 4 studies | 2 studies |
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Questions
- Which has stronger evidence, Epithalon or Thymosin Alpha-1?
- Thymosin Alpha-1 has stronger published evidence than Epithalon: tier A (Controlled human trials) vs tier B (Small human studies). Epithalon: Human data are limited to small biomarker studies and an older controlled study in retinitis pigmentosa, almost all from one research group; no randomized trial exists. Most evidence is cell and animal work. Thymosin Alpha-1: Many randomized trials, including the phase 3 TESTS trial in sepsis (BMJ 2025, no mortality benefit shown) and earlier RCTs in chronic hepatitis B. It is approved outside the US and EU but not by the FDA or EMA. Tiers rate the strength of published evidence, not effectiveness.
- Is Epithalon FDA-approved?
- Epithalon is not FDA-approved.
- Is Thymosin Alpha-1 FDA-approved?
- Thymosin Alpha-1 is not FDA-approved. Approvals listed outside the US: China (1996) — Zadaxin (thymalfasin); Singapore — Zadaxin injection, prescription-only, for chronic hepatitis B and C.
- Are Epithalon and Thymosin Alpha-1 banned in sport?
- Epithalon is prohibited in sport by WADA under section S0; Thymosin Alpha-1 is not on the WADA Prohibited List.
- How do Epithalon and Thymosin Alpha-1 work?
- In cultured human fibroblasts, Epithalon (Ala-Glu-Asp-Gly) was reported to induce expression of the telomerase catalytic subunit (hTERT), telomerase activity and telomere elongation. Thymosin alpha-1 is a 28-amino-acid thymic peptide that activates toll-like receptors (TLR2, TLR9) on dendritic cells, promoting MHC class I expression and antigen presentation.