GHK-Cu vs Thymosin beta-4
A copper-based ingredient sold in skin creams and injections for wrinkles, hair loss and healing. It speeds wound healing in rats, but no proper human trial exists. It is sold as an injection to heal tendon, muscle and joint injuries. No one has tested that use in people; the small human trials are on eye drops, the heart and safety.
Thymosin beta-4 has the stronger evidence, grade B (some human evidence) against grade C for GHK-Cu. Neither is FDA approved.
Evidence
CAnimal and cell studies
BSome human evidence
Human studies cited
Animal or cell studies cited
Why the grade
For skin repair and wound healing, the use GHK-Cu is best known for, the primary studies in hand are cell cultures and rat and mouse experiments, including a hair-growth study in fuzzy rats. The human cosmetic results that reviews describe come from manufacturer-run tests that are summarised and not published in full, so no controlled human trial with a known sample size can be named.
Thymosin beta-4 has two phase 1 safety trials in healthy volunteers (40 and 84 subjects), an 18-patient phase 3 eye-drop trial, a 96-patient randomized trial after heart attack, and a venous ulcer study. All are small and most tested topical or intravenous full-length protein for specific diseases, not the injected wound-healing use it is sold for. Animal work in rats and mice supports wound and cardiac effects. Grade B for the clinical indications under study; the injury-recovery use sold online has no trial.
FDA
Not approved
GHK-Cu is not approved by the FDA for any use. As copper tripeptide-1 it is sold in cosmetics, which sit outside FDA drug approval. The FDA placed the injectable form in Category 2 of its compounding list in 2023 over safety risks, and the agency now lists that nomination as withdrawn; it plans to bring GHK-Cu before its Pharmacy Compounding Advisory Committee by the end of February 2027.
Not approved
Thymosin beta-4 is not approved by the FDA for any use. Injectable products sold online, often labeled TB-500 (which the FDA reviewed as a seven-amino-acid fragment), are research chemicals; the FDA found no human exposure data for TB-500, and the agency has not acted on its compounding advisory committee's July 2026 vote to recommend adding TB-500 to the 503A bulks list. RGN-259 eye drops are in a phase 3 trial for neurotrophic keratopathy, and a recombinant intravenous form has been tested in heart attack patients.
Sold for
GHK-Cu is sold as an anti-aging and wound-healing peptide, in serums for wrinkles and hair thinning and as an injectable for recovery.
Thymosin beta-4 is sold as a regenerative injection for tendon, muscle and joint injuries and promoted as the full-length version of TB-500.
Studies say
Cell and animal work shows that GHK-Cu raises collagen production and speeds wound closure in rats, but the human evidence is limited to cosmetic tests reported inside reviews, which is why the grade is C.
Small randomized trials show safety and signals of benefit in eye and heart disease, but the injected use for sports injuries has never been tested in people, which is why it grades B for the studied indications and no better.
Class
Copper-binding tripeptide
Actin-regulating peptide
Route
Several routes
Several routes