Epitalon vs Thymosin alpha-1
Sold as an anti-aging peptide. The research is mostly animal and lab work from one Russian group, and no proper trial of epitalon itself has been done in people. A peptide sold by wellness clinics as an immune booster. Trials show a modest effect in hepatitis B, and a large sepsis trial found none.
Thymosin alpha-1 has the stronger evidence, grade B (some human evidence) against grade C for Epitalon. Neither is FDA approved.
Evidence
CAnimal and cell studies
BSome human evidence
Human studies cited
Animal or cell studies cited
Why the grade
The anti-aging claim rests on rodent and fruit-fly lifespan studies, monkey hormone-rhythm studies and cell-culture telomerase work, nearly all from the St Petersburg group that designed the peptide. The only human mortality data concern Epithalamin, a crude pineal extract, in a 266-person study without a described randomization or blinding, so human evidence for epitalon itself is essentially absent.
Thymosin alpha-1 has several randomized trials in chronic hepatitis B (98 and 316 patients) and a meta-analysis of five trials with 353 patients showing delayed viral suppression, which is the approved use abroad. The 1,106-patient TESTS phase 3 trial in sepsis found no mortality benefit. The general immune-boosting use it is sold for in the US has no controlled trials, so the compound grades B on its hepatitis B evidence and D on the wellness claims.
FDA
Not approved
Not approved by the FDA for any use and sold as a research chemical. In July 2026 the FDA's Pharmacy Compounding Advisory Committee voted, over the objection of FDA staff, to recommend adding epitalon to the list of substances pharmacies may compound for insomnia; that recommendation is advisory and the FDA had not acted on it as of October 2026.
Not approved
Thymosin alpha-1 is not approved by the FDA for any use. It is approved as thymalfasin (Zadaxin) in more than 35 other countries for hepatitis B and C and as an immune adjuvant. In the United States it was taken off the FDA's Category 2 compounding list after its nominators withdrew it, and in December 2024 the Pharmacy Compounding Advisory Committee voted 17 to 4 against adding it to the 503A bulks list; it is sold online as a research chemical.
Sold for
Epitalon is sold as a telomerase-activating longevity peptide that resets the pineal gland and extends lifespan.
Thymosin alpha-1 is sold by wellness clinics as an immune-system booster for infections, cancer support, autoimmune disease and long COVID.
Studies say
Animal and cell studies from a single research school plus one weak human study of a different preparation put this at C.
Randomized trials support a modest, delayed antiviral effect in chronic hepatitis B, a large trial found no benefit in sepsis, and there are no trials of the immune-boosting uses marketed in the US, which is why it grades B.
Class
Pineal tetrapeptide (Ala-Glu-Asp-Gly)
Immunomodulatory peptide
Route
Injection
Injection