Comparison
Thymogen vs Thymosin Alpha-1
Thymogen 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.
| Thymogen | 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 | Immune function research, Infection recovery 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 |
Thymogen
Thymogen 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. A dipeptide derived from thymalin, registered in Russia as an immunostimulant. 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.
Thymogen vs Thymosin Alpha-1: common questions
What is the difference between Thymogen and Thymosin Alpha-1?
Thymogen is bioregulators and Thymosin Alpha-1 is thymic & immune, so they act on different pathways. Thymogen: A short peptide bioregulator directed at the thymus, 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, Thymogen or Thymosin Alpha-1?
Thymosin Alpha-1 has the stronger evidence base (clinical trials, about 40 human studies) compared with Thymogen (preliminary human).
Are Thymogen and Thymosin Alpha-1 FDA approved?
Neither is FDA approved for any indication.
References
Regulatory and primary sources
- PubChem compound record (CID 100094) ↗ · 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
- Synthetic and natural immunomodulators acting as interferon inducers.Curr Pharm Des 2009.PubMed 19355963 · doi:10.2174/138161209787846847
- The First Reciprocal Activities of Chiral Peptide Pharmaceuticals: Thymogen and Thymodepressin, as Examples.Int J Mol Sci 2024.PubMed 38732260 · doi:10.3390/ijms25095042
- [Influence of peptides from pineal gland on thymus function at aging].Adv Gerontol 2010.PubMed 21510076
- [Glutoxim in the complex treatment of tuberculosis].Antibiot Khimioter 2002.PubMed 12087719
- [Current aspects of pathogenetic therapy in tuberculosis].Ter Arkh 2011.PubMed 21961327
- [Thiopoeitins in the treatment of tuberculosis].Probl Tuberk Bolezn Legk 2007.PubMed 17657963
- [Thymogen in the complex treatment of inflammatory diseases of the female genital system].Akush Ginekol (Mosk) 1992.PubMed 1476231
- [Application of ozonated perftoran in the treatment of spreaded peritonitis].Klin Khir 2014.PubMed 24923143
- 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.