Evidence Grading Methodology
Every stack, peptide monograph, and comparison page on PeptideStacks carries an evidence grade. Grades are conservative by default and are intended to signal how much weight you should put on the claims that follow.
Grade definitions
Approved medicine or multiple robust human clinical studies for the specific context discussed.
Some human clinical evidence, but limited, indirect, or not specific to the claimed use.
Preclinical animal evidence with a plausible mechanism; weak or absent human translation.
In vitro / cell / mechanistic evidence only.
Theoretical, anecdotal, or weak evidence base.
High uncertainty, high-risk extrapolation, or claims unsupported by current evidence.
How grades are assigned
Grades are assigned conservatively based on the best available evidence for the specific claim being made. A peptide with strong human evidence for one indication does not automatically score the same grade for a different indication. Combination evidence is graded separately from monotherapy evidence: a stack of two peptides each with human data may still grade C if the combination itself has not been directly studied.
- Grade A requires a UK or EU/US-approved indication, or multiple independent RCTs supporting the specific use described.
- Grade B means there is human clinical evidence, but it is limited, indirect, off-label, or from a single trial.
- Grade C covers preclinical evidence — typically animal models — with plausible mechanism but no robust human translation.
- Grade D is in vitro / cell / mechanistic evidence only.
- Grade E is theoretical or anecdotal — no controlled evidence.
- Grade X is for claims that are high-uncertainty, high-risk extrapolations, or are unsupported by current evidence.
What grades do not mean
An evidence grade is not a safety rating. It is not a recommendation that a compound should be used. A Grade A medicine can be unsafe outside its approved indication and dose; a Grade C peptide can become safer once human evidence accumulates, or be revealed as harmful. Grades describe the state of evidence, nothing more.
Re-grading and disagreement
We re-grade pages when new evidence appears. If you believe a page is over- or under-graded, use our corrections policy.
Conservative defaults
Where a page has not yet been individually graded by an editor, the site assigns a conservative default based on the underlying compound class, regulatory status, and combination type. These defaults err on the side of lower grades and higher uncertainty.