Here’s what the sources actually cover.
These are the sources cited on Topical Peptides. The notes explain what each can tell us. A promising finding is easier to weigh when the preparation and setting stay beside it.
GHK-Cu and the skin
The GHK skin review reports encouraging face- and eye-cream findings. Its underlying cosmetic reports include a conference presentation, a university report and a book chapter, rather than medical-journal papers. We describe them as reports through a review, not proof for every cream.
The topical GHK review explains the difficulty of getting the ingredient through skin’s outer barrier. It also points to the shortage of clinical studies. It helps explain why the whole preparation matters.
The skin experiment measured copper passing through and remaining in isolated human skin. It measured copper, not passage of intact GHK-Cu. No one’s wrinkles were tested in that lab setup.
The post-laser study had 13 people complete it. Measured redness, wrinkles and overall skin quality didn’t significantly improve with the GHK-Cu regimen, although satisfaction was higher. Freshly treated skin is a particular setting.
The scalp trial used copper-free GHK with 5-aminolevulinic acid. This was a small trial in men whose hair loss followed the male pattern. The mixture beat placebo on the change in counted hairs. It showed no significant edge for either hair length or thickness. It didn’t test GHK-Cu, and it wasn’t a face-cream study.
Medicines and other routes
The semaglutide safety review covers tested semaglutide medicines, including the helper ingredient used for oral absorption. That delivery work offers no evidence for a cream.
The STEP 1 paper looked at injections of semaglutide. The adults enrolled didn’t have diabetes. They qualified through obesity, or through overweight together with a related health condition. Weight loss was greater on average than with placebo, alongside lifestyle support. The route is part of that result.
Wegovy prescribing information covers semaglutide tablets and injections, including their safety warnings. Approval of those medicines doesn’t extend to compounded versions.
FDA’s thymosin alpha-1 presentation describes online spray marketing, reviews injection evidence and raises quality concerns. Describing a marketed spray isn’t evidence that it works. The injection findings don’t establish nasal safety or effectiveness.
The rules behind the wording
FDA’s compounding explanation says compounded medicines aren’t FDA-approved. The particular preparation reaches patients with no prior FDA verification of its effectiveness, safety or quality. Prescribing and approval are separate matters.
FDA’s peptide safety-risk page, current as of April 22, 2026, lists injectable GHK-Cu and thymosin alpha-1 under withdrawn nominations. Their safety concerns remain. Withdrawal isn’t clearance.
FDA’s cosmetic regulation page explains why intended use matters. An appearance claim and a claim to change how the body works can put products under different rules, even when both go on skin.