Guides · Thymalin vs thymosin alpha-1
Thymalin vs thymosin alpha-1: two thymus peptides, very different evidence
Both come from thymus research but they are different things. Thymalin is a polypeptide extract of thymus, given by injection in Russia, with human data that come mostly from the group that developed it. Thymosin alpha-1 is a single 28-amino-acid peptide first isolated from thymus and now made synthetically. It has been tested in randomized trials, mainly in Asia and Italy, though a 2026 Cochrane review rated that evidence (in chronic hepatitis B) as very low certainty. Neither is FDA-approved. Oral thymus capsules such as Thymusol are a third option with no human trials.
Written by The Bioregulator Atlas editorial team · Medical review pending · Facts and prices checked Oct 7, 2026
- Thymalin
- Thymus polypeptide extract; active dipeptides KE and EW proposed; human data mostly from the originating group(source)
- Thymosin alpha-1
- Single 28-amino-acid peptide; Cochrane 2026: 10 RCTs, 1,349 people (hepatitis B), very low-certainty evidence(source)
- FDA
- Thymosin alpha-1: safety information "inadequate" for compounding (nomination withdrawn)(source)
- Oral capsules
- Thymusol $67.50 / 30 caps, Vita Defender $107.50 / 30 caps (Vita-Stream, Oct 6, 2026); no human trials
What each one is
Thymalin: a mixture of peptides extracted from animal thymus, developed in the Soviet Union and used as an injectable medicine in Russia. Its developers identify the dipeptides Lys-Glu (KE) and Glu-Trp (EW) as active components.
Thymosin alpha-1 (thymalfasin): one defined 28-amino-acid peptide, originally isolated from thymus tissue and now produced synthetically. It is not FDA-approved in the US.
Human studies
Thymalin: the most-cited human report followed 266 older people for 6 to 8 years, some of whom received Thymalin and/or Epithalamin injections. The developers reported fewer respiratory infections and lower mortality than in controls; it was not blinded or placebo-controlled.
Thymosin alpha-1: a 2026 Cochrane review found 10 randomized trials (1,349 people, published 1991–2018) in chronic hepatitis B. Thymosin alpha-1 may reduce mortality and serious adverse events, but the authors rated the evidence low to very low certainty and said they are not sure of the effect. That is a medical use under specialist care, not a reason to self-inject.
Lab studies and reviews
Thymalin: 2020 cell-culture work reported changes in differentiation markers of human blood stem cells, and a 2023 computer-docking and bioinformatics paper proposed how KE and EW might affect gene expression.
Thymosin alpha-1: a 2025 review discusses its proposed role in immune aging. Reviews summarize; they do not add new evidence in people.
- Lab / cell studyKhavinson et al. 2020, Bull Exp Biol Med: Thymalin and human hematopoietic stem cells in culture
- Lab / cell studyLinkova et al. 2023, Int J Mol Sci: KE and EW dipeptides of Thymalin, docking and bioinformatics
- ReviewSimonova et al. 2025, Int J Mol Sci: aging and thymosin alpha-1 (review)
Legal status in the US
Neither Thymalin nor thymosin alpha-1 is FDA-approved. Thymosin alpha-1 appears on the FDA's page of bulk substances that may present significant safety risks in compounding, among withdrawn nominations, with the note that safety-related information is inadequate for the agency to understand the extent of any safety issues.
Oral thymus bioregulator capsules are sold as dietary supplements. They are not Thymalin, not thymosin alpha-1 and have no human trials of their own.
Oral thymus capsules (Vita-Stream)
Vita-Stream does not sell Thymalin or thymosin alpha-1. These are oral dietary supplements with no human trials. Ask a clinician first if you have an immune condition or take immunosuppressants. Not intended to diagnose, treat, cure or prevent any disease.
- ThymusolVita Peptides house line · thymus
Vita Peptides house-line thymus capsule; labeled to support thymus function and normal immune-system balance.
30 caps $67.50 · 60 caps $135.00 (Vita-Stream, Oct 6, 2026)
- Vita DefenderVita Peptides house line · thymus, adrenal and pituitary
Thymus, adrenal and pituitary peptides in one capsule.
30 caps $107.50 · 60 caps $215.00 (Vita-Stream, Oct 6, 2026)
- Vladonix (A-6)Sold by Vita-Stream · thymus
The original GARMONIA thymus Cytomax (A-6).
Use code KymataLabs at checkout
FAQ
Is Thymalin the same as thymosin alpha-1?
No. Thymalin is a mixture of thymus-derived peptides used as an injectable in Russia. Thymosin alpha-1 is one defined 28-amino-acid peptide, made synthetically.
Which has better evidence?
Thymosin alpha-1 has more randomized trials, though a 2026 Cochrane review in chronic hepatitis B rated the evidence low to very low certainty. Thymalin's human data come mostly from its developers and were not blinded trials.
Is thymosin alpha-1 FDA-approved?
No. The FDA lists it among withdrawn nominations on its page of bulk substances that may pose significant safety risks in compounding, saying the safety information is inadequate.
Is Thymusol a form of Thymalin?
No. Thymusol is an oral thymus peptide supplement from the Vita Peptides line. The Thymalin injection studies do not apply to it, and it has no human trials of its own.
Do you earn money from these links?
Yes. Vita-Stream links are affiliate links (marked Paid), and orders placed with the code KymataLabs are credited to our affiliate account at no extra cost to you. It does not change the evidence notes.
Related on the Atlas
- Immune support hub
- Thymalin vs thymus bioregulator capsules
- Thymalin: compound profile
- Vilon (Lys-Glu): compound profile
- Immune system stack
Other guides: Epitalon vs Epithalamin · Bioregulators vs peptides · All health hubs
Not medical advice. Medical review pending: this page has not yet been reviewed by a licensed clinician. Statements about dietary supplements have not been evaluated by the Food and Drug Administration; these products are not intended to diagnose, treat, cure or prevent any disease. Compounded medicines are not FDA-approved. Prices change often; confirm on the seller's page.