About This Reference Desk

What Physician-Only Peptides is

Physician-Only Peptides is an independent editorial reference desk covering the published research on two peptides studied for immune and thymic modulation: Thymosin Alpha-1 and Thymulin, with Thymosin Alpha-1 as the lead. The site exists to make a nuanced and frequently misrepresented literature legible — to tell a reader, in plain language and with citations, what each compound was actually studied for, in which species, and how far that evidence reaches.

The organizing idea is precision about compound identity. The thymic peptide space is cluttered with similar-sounding names: thymosin alpha-1, thymosin beta-4, thymulin, thymalin, thymopentin, nonathymulin. Each is a distinct molecule with a distinct evidence base. This desk keeps them clearly separated, cites every claim to a numbered source, and does not allow the clinical record of one compound to silently migrate to another.

Each compound has its own page; a comparison page lines them up side by side; and a single shared references list aggregates every source.

How it is compiled

Three principles govern what appears on this site.

First, everything is anchored to the peer-reviewed literature. Every research claim is tied to a numbered citation — PubMed-indexed journal articles and reviews, with DOIs and PubMed links — collected on the references page. Where a finding comes from a review rather than a primary study, the review is cited as such.

Second, the evidence is reported at its true strength. A phase-3 null RCT (TESTS) is reported as null; preclinical-only evidence is described as preclinical-only; gene-therapy delivery models are distinguished from direct peptide administration. The site does not interpolate from animal findings to human recommendations, does not describe study-reported doses as advice, and does not soften inconvenient null results.

Third, compound identity is treated as a first principle. Consumer sources frequently conflate thymulin with thymalin, thymosin alpha-1 with thymosin beta-4, and approved clinical data with research-chemical use. Each compound page opens with an explicit statement of what the compound is and is not, and the comparison page makes structural and evidentiary distinctions across both.

What it is not

Physician-Only Peptides is not a store, not a clinic, and not a source of medical advice. It does not sell, supply, source, or broker any peptide or research chemical, and it has no affiliate or referral relationship with any vendor. It does not employ clinicians, diagnose conditions, or prescribe anything.

The peptides discussed here have different regulatory statuses. Thymosin Alpha-1 (thymalfasin) is an approved pharmaceutical in more than 35 countries; it is not FDA-approved in the United States. Thymulin has no approved human indication anywhere. In neither case does this desk's summary of the research constitute guidance on human use. Readers interested in any condition described in the underlying research should consult a licensed clinician operating within their own jurisdiction, working with regulated, evidence-based options.

The value this site offers is a calm, accurate, and honestly qualified map of the published thymic peptide literature — nothing more, and nothing it pretends to be.