Every claim on this site carries an evidence tier. The tier describes the strength of the evidence behind that claim. It does not describe how good, safe, or useful the compound is.
A compound can have strong evidence that it does very little. Another can have almost no evidence either way. The tier tells you which situation you are looking at.
The tiers
E1 · Approved-label evidence
The claim comes from FDA or EMA approved labelling for a specific indication. This is the highest bar on the site. A regulator reviewed the underlying trial data and approved the wording.
E2 · Human clinical evidence
A registered or peer-reviewed human trial with reported results. The trial is named and linked, so you can read what it actually measured and in whom.
E3 · Early human evidence
Small, open-label, uncontrolled, a case series, or a registered trial with no published results yet. Real human data, but not enough of it to lean on.
E4 · Preclinical only
Animal studies, or work in cell culture. Not demonstrated in humans. A large share of the compounds covered here sit at this tier, and that is the single most important fact about most of them.
E5 · Community-reported
Forum posts, circulated protocols, vendor material. This is reported, not evidence. It appears on entries because people search for it and deserve to know where it came from and how much weight it carries, which is very little. It is kept in its own visually separate section for exactly that reason.
Q · Disputed or withdrawn
Retracted, contradicted by later work, or a claim that could not be traced to any source at all.
Why animal data is kept apart
A result in rats is a reason to run a human trial. It is not a result in people.
That distinction gets blurred constantly in writing about peptides, usually by describing a rodent finding in language that sounds like a human outcome. On this site an animal finding is tagged E4 and the entry says plainly that it has not been shown in humans.
The dosing rule
If no named source reports a figure, the entry says no established dosing and prints no number.
This is not a style preference. The dosing field in this site’s database refuses to save a value unless a reference record is attached to it, so an unsourced number cannot be published here even by mistake.
Where a figure does appear, it describes what a source reported in a research setting. It is not a recommendation, not a protocol, and not an instruction.
Reading the chips
Each tier appears as a small chip carrying its letter code, a distinct shape, and a colour. Three signals rather than one, so the tier stays readable in greyscale, in print, and with any form of colour vision deficiency.
What a tier is not
A tier grades evidence. It says nothing about safety, quality, purity, or legality.
E4 does not mean a compound is dangerous. E1 does not mean it is appropriate for anyone in particular. The tier answers how much is actually known, which is a different question from whether something is a good idea.