Comparison
Epitalon vs Thymosin Alpha-1
Epitalon is bioregulators; Thymosin Alpha-1 is thymic & immune. They are compared here because they are frequently considered against each other, not because they act alike.
On published evidence alone, Thymosin Alpha-1 is the better documented of the two (clinical trials). That is a statement about the state of the literature, not a recommendation.
| Epitalon | Thymosin Alpha-1 | |
|---|---|---|
| Class | Bioregulators | Thymic & immune |
| Evidence | Preliminary human | Clinical trials |
| Human trials | ~2 | ~40 |
| Half-life | Not established | ~2 hours |
| Reported range | 100-200 mcg | 1.6-3.2 mg |
| Frequency | Once daily for 10-20 day courses, 2-3 courses per year | 2x weekly |
| Routes | Subcutaneous, Oral, Intramuscular | Subcutaneous |
| FDA approved | No | No |
| Research use only | Yes | Yes |
| Banned in sport | No | No |
| Studied for | Longevity research, Melatonin rhythm, Telomere research | Chronic hepatitis B and C, Immune modulation, Vaccine adjuvant research, Sepsis research |
| Reported side effects | Injection-site reactions, Transient fatigue | Injection-site erythema, Transient fatigue, Mild flu-like symptoms |
Epitalon
Epitalon is one of the short peptide bioregulators characterised by Vladimir Khavinson, a series of di- to tetrapeptides each associated with a specific tissue. The proposed mechanism is direct interaction with DNA promoter regions to modulate transcription of tissue-specific genes, restoring protein synthesis in ageing or damaged tissue. It is the most studied compound in the series, associated in the original work with restoration of melatonin rhythm and with telomerase activation in cell culture. Nearly all supporting work comes from a single research group and has not been independently replicated under contemporary trial standards, which is the central limitation of the entire class and should be stated on every page in it.
Thymosin Alpha-1
Thymosin alpha-1 is a 28-residue peptide originally isolated from thymic tissue. It acts largely through Toll-like receptor signalling on dendritic cells, promoting maturation of T cells and enhancing Th1 responses, natural killer cell activity and antigen presentation. Unlike most compounds on this site it has a substantial approved clinical history outside the US, including as an adjuvant in hepatitis B and C and in sepsis research.
Epitalon vs Thymosin Alpha-1: common questions
What is the difference between Epitalon and Thymosin Alpha-1?
Epitalon is bioregulators and Thymosin Alpha-1 is thymic & immune, so they act on different pathways. Epitalon: A short peptide bioregulator directed at the pineal gland, from the Khavinson series developed at the St. Petersburg Institute of Bioregulation and Gerontology. Thymosin Alpha-1: A thymic immunomodulatory peptide approved in more than 30 countries for hepatitis B and C, though not in the United States.
Which has stronger evidence, Epitalon or Thymosin Alpha-1?
Thymosin Alpha-1 has the stronger evidence base (clinical trials, about 40 human studies) compared with Epitalon (preliminary human).
Are Epitalon and Thymosin Alpha-1 FDA approved?
Neither is FDA approved for any indication.
References
Regulatory and primary sources
- PubChem compound record (CID 219042) ↗ · structure, identifiers, synonyms
- FDA: Unapproved drugs and "research use only" products ↗ · regulatory status of non-approved products
- PubChem compound record (CID 16130571) ↗ · structure, identifiers, synonyms
- CAS Registry Number 62304-98-7 ↗ · chemical identity
Published literature
- Peptides and Ageing.Neuro Endocrinol Lett 2002.PubMed 12374906
- Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions.J Am Acad Orthop Surg Glob Res Rev 2026.PubMed 41490200 · doi:10.5435/JAAOSGlobal-D-25-00236
- Overview of Epitalon-Highly Bioactive Pineal Tetrapeptide with Promising Properties.Int J Mol Sci 2025.PubMed 40141333 · doi:10.3390/ijms26062691
- Peptide Regulation of Cell Differentiation.Stem Cell Rev Rep 2020.PubMed 31808038 · doi:10.1007/s12015-019-09938-8
- Peptides: Prospects for Use in the Treatment of COVID-19.Molecules 2020.PubMed 32987757 · doi:10.3390/molecules25194389
- [Peptidergic regulation of expression of cellular aging marker proteins in buccal epithelium.].Adv Gerontol 2024.PubMed 39742404
- Artificial life extension. The epigenetic approach.Ann N Y Acad Sci 1994.PubMed 8010616 · doi:10.1111/j.1749-6632.1994.tb56852.x
- Effects of pineal peptide preparation Epithalamin on free-radical processes in humans and animals.Neuro Endocrinol Lett 2001.PubMed 11335874
- beta-Thymosins.Ann N Y Acad Sci 2007.PubMed 17468232 · doi:10.1196/annals.1415.018
- Thymosin alpha-1.Am J Health Syst Pharm 2001.PubMed 11381492 · doi:10.1093/ajhp/58.10.886
- T-cell adjuvants.Int J Immunopharmacol 1994.PubMed 7806429 · doi:10.1016/0192-0561(94)90090-6
- Thymic endocrinology.Ann N Y Acad Sci 1998.PubMed 9629262 · doi:10.1111/j.1749-6632.1998.tb09574.x
- Unmet needs in cystic fibrosis.Expert Opin Biol Ther 2018.PubMed 30063865 · doi:10.1080/14712598.2018.1484101
- Structures of Thymosin Proteins.Vitam Horm 2016.PubMed 27450728 · doi:10.1016/bs.vh.2016.04.009
- Efficacy of thymosin α1 for sepsis: a systematic review and meta-analysis of randomized controlled trials.Front Cell Infect Microbiol 2025.PubMed 40969554 · doi:10.3389/fcimb.2025.1673959
- Aging and Thymosin Alpha-1.Int J Mol Sci 2025.PubMed 41373628 · doi:10.3390/ijms262311470
Literature retrieved from PubMed on October 16, 2026, favouring human studies and reviews. Numbered markers in the text show which paper supports which statement; uncited entries are background reading.