A Peter Peptides research project
Peptide safety,
ranked conservatively.
Twelve peptides compared by human safety data, regulatory status, known adverse effects, and the size of the evidence gaps.
S and A stay empty. That is intentional. Every peptide on this page carries some combination of known risk, limited evidence, or unresolved uncertainty.
12 peptides reviewed
Relative safety profile
Method & limitations
This is not a “safe vs. unsafe” list.
The tiers compare relative safety confidence, not effectiveness and not whether someone should use a compound. A B-tier peptide can still cause serious adverse effects. An F-tier entry may be ranked low primarily because reliable human safety data are missing.
Route and product quality matter. For example, the GHK-Cu ranking is framed around topical/dermal use; injectable GHK-Cu has substantially greater uncertainty and FDA-identified concerns around immunogenicity and peptide-related impurities.
Educational and harm-reduction context only. No dosing, sourcing, cycle, treatment, or diagnostic guidance.
Primary evidence
Sources used for the rankings.
FDA — compounded peptide safety concerns ↗
FDA — approved vs. unapproved GLP-1 products ↗
FDA — tirzepatide prescribing information ↗
FDA — tesamorelin prescribing information ↗
FDA — bremelanotide prescribing information ↗
PubMed — CJC-1295 human study ↗
PubMed — thymosin beta-4 human safety study ↗
PubMed — melanotan safety review ↗