RKH is a tripeptide of arginine, lysine and histidine, listed in regenerative and cosmetic peptide catalogs. Unlike most entries in this formulary, there is very little to report about it — and that absence is itself the clinically relevant fact.
This guide situates RKH within the broader field of peptide therapy and is written for clinicians. It is clinical education, not medical advice, and nothing here should be read as a treatment recommendation or protocol.
What is actually known
RKH consists of three amino acids: arginine, lysine and histidine. All three are basic amino acids carrying positive charge at physiologic pH, which gives the tripeptide a strongly cationic character.
Short cationic peptides as a class have been studied for properties including metal ion binding and interaction with negatively charged cell membranes, and some — notably GHK-Cu — have substantial research behind them. Those general class properties are the extent of what can be said with confidence about RKH.
Specific claims about RKH's biological effects in humans are not supported by an accessible published literature. There is no meaningful body of clinical trials, and no substantive preclinical work that establishes a defined mechanism or effect.
Why we state this plainly
It would be straightforward to write a plausible page about RKH. Its amino acid composition supports reasonable-sounding speculation about copper binding, wound healing or antimicrobial activity, all of which are documented properties of other short cationic peptides.
That would be inference dressed as information, and it is precisely how a great deal of peptide marketing content is produced — extrapolating from a related compound's evidence base to a compound that has none of its own. The same pattern appears with Pentadeca Arginate borrowing BPC-157's literature.
For a clinician being asked about a compound, the honest answer — that the evidence does not exist — is more useful than a confident-sounding summary assembled from adjacent research. Absence of evidence is a finding. It does not prove a compound is inert, and it does mean no one can responsibly claim to know what it does.
How to evaluate an unfamiliar peptide
The approach that serves clinicians for any unfamiliar compound is consistent. Search the peptide by sequence and by every synonym, not just the marketing name, since vendors frequently rename compounds. Check whether the results are human trials, animal studies, cell culture, or purely vendor material. Establish whether a defined receptor or mechanism has been characterized. And verify regulatory status directly.
Applying that process to RKH returns very little, which is the answer. Applying it to BPC-157 returns a substantial animal literature with limited human data. Applying it to semaglutide returns large controlled human trials. Those are three very different situations, and the process distinguishes them reliably.
Our peptide formulary tags every agent with its regulatory status so that this evaluation starts from an accurate baseline.
Learn peptides the right way
Empire Medical Training's Peptide Therapy Master Course is a CME-accredited program covering evaluating peptide claims against the literature, patient selection, monitoring, regulatory status, and compliant sourcing — taught by board-certified physicians. Available in person and via livestream. It is also Course 1 of Empire’s Peptide Therapy Certification, which adds business, marketing and healthcare-law training, a documented case series and a final exam.
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