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Comparison

GHK-Cu vs Zn-Thymulin

GHK-Cu is healing & repair; Zn-Thymulin is thymic & immune. They are compared here because they are frequently considered against each other, not because they act alike.

On published evidence alone, GHK-Cu is the better documented of the two (clinical trials). That is a statement about the state of the literature, not a recommendation.

GHK-Cu Zn-Thymulin
Class Healing & repair Thymic & immune
Evidence Clinical trials Preliminary human
Human trials ~15 ~2
Half-life ~30 minutes (systemic) ~30 minutes
Reported range 1-2 mg 100-200 mcg
Frequency Daily topical, or subcutaneous in research protocols Daily topical application
Routes Topical, Subcutaneous Topical, Subcutaneous
FDA approved No No
Research use only No Yes
Banned in sport No No
Studied for Skin repair and anti-ageing, Wound healing, Hair follicle stimulation Immune modulation research, Hair loss research
Reported side effects Local irritation, Transient redness, Injection-site reactions Scalp irritation, Injection-site reactions

GHK-Cu

GHK is a tripeptide present in human plasma that declines markedly with age, and it binds copper(II) with high affinity to form GHK-Cu. The complex modulates expression of a large set of genes involved in tissue remodelling, stimulating collagen, elastin and glycosaminoglycan synthesis while influencing antioxidant and anti-inflammatory pathways. Its dermatological evidence is comparatively strong and includes controlled human trials; the systemic injectable use is far less supported.

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.

GHK-Cu vs Zn-Thymulin: common questions

What is the difference between GHK-Cu and Zn-Thymulin?

GHK-Cu is healing & repair and Zn-Thymulin is thymic & immune, so they act on different pathways. GHK-Cu: A naturally occurring copper-binding tripeptide with the strongest human evidence base of any compound in the healing group, mostly topical. 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, GHK-Cu or Zn-Thymulin?

GHK-Cu has the stronger evidence base (clinical trials, about 15 human studies) compared with Zn-Thymulin (preliminary human).

Are GHK-Cu and Zn-Thymulin FDA approved?

Neither is FDA approved for any indication.

References

Regulatory and primary sources

  1. PubChem compound record (CID 139035031) ↗ · structure, identifiers, synonyms
  2. CAS Registry Number 89030-95-5 ↗ · chemical identity
  3. FDA: Unapproved drugs and "research use only" products ↗ · regulatory status of non-approved products

Published literature

  1. Pickart L, Margolina A. Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data.Int J Mol Sci 2018.PubMed 29986520 · doi:10.3390/ijms19071987
  2. Pickart L, Vasquez-Soltero JM, Margolina A. GHK Peptide as a Natural Modulator of Multiple Cellular Pathways in Skin Regeneration.Biomed Res Int 2015.PubMed 26236730 · doi:10.1155/2015/648108
  3. Mayfield CK, Bolia IK, Feingold CL, et al.. Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians.Am J Sports Med 2026.PubMed 41476424 · doi:10.1177/03635465251357593
  4. Rahman OF, Lee SJ, Seeds WA. 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
  5. Mendias CL, Awan TM. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance.Sports Med 2026.PubMed 41966639 · doi:10.1007/s40279-026-02437-0
  6. Ogórek K, Nowak K, Wadych E, et al.. Are We Ready to Measure Skin Permeation of Modern Antiaging GHK-Cu Tripeptide Encapsulated in Liposomes?.Molecules 2025.PubMed 39795193 · doi:10.3390/molecules30010136
  7. Pickart L. The human tri-peptide GHK and tissue remodeling.J Biomater Sci Polym Ed 2008.PubMed 18644225 · doi:10.1163/156856208784909435
  8. Renke G, Chinellato L. Therapeutic Peptides in Aesthetic, Metabolic and Endocrine Conditions: Effects, Safety, Clinical Applications, and Future Perspectives.Int J Mol Sci 2026.PubMed 42123471 · doi:10.3390/ijms27093890
  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.