Search ↗

Comparison

Thymalin vs Zn-Thymulin

Both are thymic & immune, so the meaningful differences are in kinetics, evidence and regulatory status.

Thymalin Zn-Thymulin
Class Thymic & immune Thymic & immune
Evidence Preliminary human Preliminary human
Human trials ~5 ~2
Half-life Not established ~30 minutes
Reported range 10-20 mg 100-200 mcg
Frequency Once daily for 5-10 days Daily topical application
Routes Intramuscular, Subcutaneous Topical, Subcutaneous
FDA approved No No
Research use only Yes Yes
Banned in sport No No
Studied for Immune restoration research, Geriatric immunity research Immune modulation research, Hair loss research
Reported side effects Injection-site reactions, Transient fatigue Scalp irritation, Injection-site reactions

Thymalin

Thymalin is a mixture of polypeptide fractions isolated from bovine thymus rather than a single defined molecule, which is an important distinction from thymosin alpha-1. It is reported to restore T-lymphocyte differentiation and normalise immune indices in immunodeficiency states. The frequently cited evidence is a long-running Russian geriatric cohort reporting reduced mortality; that work has not been replicated under contemporary trial standards.

Zn-Thymulin

Thymulin is a nonapeptide produced by thymic epithelial cells that is biologically active only when bound to zinc, which is why zinc status directly governs its function. It influences T-cell differentiation and has documented anti-inflammatory and antinociceptive activity in animal models. Separately, topical thymulin products are marketed for hair loss, which accounts for most current commercial interest, but a hair-growth benefit has not been established in humans.

Thymalin vs Zn-Thymulin: common questions

What is the difference between Thymalin and Zn-Thymulin?

Both are thymic & immune. Thymalin: A polypeptide fraction extracted from calf thymus, used clinically in Russia and studied in long-term geriatric cohorts. Zn-Thymulin: A zinc-dependent thymic nonapeptide, of interest for immune signalling and marketed as a topical hair-loss product, though a hair benefit is not established in humans.

Which has stronger evidence, Thymalin or Zn-Thymulin?

They sit at the same evidence level: preliminary human. Thymalin has about 5 human studies and Zn-Thymulin about 2.

Are Thymalin and Zn-Thymulin FDA approved?

Neither is FDA approved for any indication.

References

Regulatory and primary sources

  1. PubChem compound record (CID 3085284) ↗ · structure, identifiers, synonyms
  2. FDA: Unapproved drugs and "research use only" products ↗ · regulatory status of non-approved products

Published literature

  1. Khavinson VKh. Peptides and Ageing.Neuro Endocrinol Lett 2002.PubMed 12374906
  2. Khavinson VKh, Morozov VG. [Geroprotective effect of thymalin and epithalamin].Adv Gerontol 2002.PubMed 12577695
  3. Litvinenko GI, Shurlygina AV, Dergacheva TI, et al.. Chrono- and Immunocorrection of Inflammatory Disorders of Internal Reproductive Organs in Women of Reproductive Age.Bull Exp Biol Med 2015.PubMed 26033592 · doi:10.1007/s10517-015-2890-0
  4. Khavinson VKh, Morozov VG. Peptides of pineal gland and thymus prolong human life.Neuro Endocrinol Lett 2003.PubMed 14523363
  5. Lin'kova NS, Poliakova VO, Kvetnoĭ IM, et al.. [Characteristics of the pineal gland and thymus relationship in aging].Adv Gerontol 2011.PubMed 21809618
  6. Lin'kova NS, Poliakova VO, Trofimov AV, et al.. [Influence of peptides from pineal gland on thymus function at aging].Adv Gerontol 2010.PubMed 21510076
  7. Musienko GV. [Thymalin in the combined treatment of parkinsonism patients].Lik Sprava 1999.PubMed 10424021
  8. Domina EA. Chornobyl catastrophe: cytogenetic effects of low dose ionizing radiation and their modification.Exp Oncol 2016.PubMed 28230819
  9. Hadden JW. Thymic endocrinology.Ann N Y Acad Sci 1998.PubMed 9629262 · doi:10.1111/j.1749-6632.1998.tb09574.x
  10. Hadden JW. Immunodeficiency and cancer: prospects for correction.Int Immunopharmacol 2003.PubMed 12860163 · doi:10.1016/S1567-5769(03)00060-2
  11. Licastro F, Mocchegiani E, Masi M, et al.. Modulation of the neuroendocrine system and immune functions by zinc supplementation in children with Down's syndrome.J Trace Elem Electrolytes Health Dis 1993.PubMed 8019155

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.

Read this first This page compares published reference data. It is not medical advice and not a recommendation to use either compound. Several compounds documented on this site are not approved for human use.