The peptide guide
What peptides actually are, how to read the evidence behind them, and the questions people ask most — answered honestly, with sources. No hype, no dosing advice.
What a peptide actually is
A peptide is a short chain of amino acids — the same building blocks as proteins, just smaller. The body makes thousands of them as signalling molecules. “Peptide therapy” covers a huge, uneven range: a few are approved drugs with large trials behind them (semaglutide, tesamorelin), while many sold online are research compounds with little or no human evidence. Lumping them together is the single biggest mistake in this space.
How to read the evidence
- Human > animal > cell. An effect in rodents routinely fails to translate. Preclinical is a reason to study, not proof.
- Approved status ≠ effective for your goal. A drug approved for one indication isn't evidence for an off-label use.
- Popularity isn't data. Influencer and forum consensus says nothing about whether a compound works or is safe.
- Specific numbers need a source. If a figure can't be traced to a paper, label, or registry, treat it as marketing.
The methodology page shows the full scoring model and the three-layer citation audit behind every grade.
Frequently asked questions
What's the difference between research-grade and pharmaceutical-grade peptides?
“Pharmaceutical-grade” means a compound made under regulated manufacturing for human use, with identity, purity, sterility, and endotoxin all controlled and an approved label. “Research-grade” / “research-use-only” material is sold for laboratory use and is not approved or quality-assured for human administration — purity and sterility vary, and a Certificate of Analysis reports chemistry only, not sterility or safety. The label is a regulatory status, not a safety guarantee.
How do I know if a peptide is working?
For most research peptides there's no validated biomarker, so people rely on subjective change — exactly where placebo and expectation effects are strongest. The evidence-first approach is to define one or two objective measures before starting (a lab value, a performance number, a photo), track them over time, and weigh them against what's actually published. The tier board shows how strong that evidence is.
Can I stack peptides with TRT or GLP-1?
Many people run peptides alongside TRT/HRT or a GLP-1, and PepCue tracks all of them on one timeline. But interactions, additive side effects, and monitoring needs are real and individual — a question for a qualified prescriber, not a generic rule. We don't recommend protocols or doses.
How long can I keep a reconstituted vial?
It depends on the peptide's stability, the diluent (bacteriostatic water has a preservative; sterile water doesn't), temperature, and sterile handling. There's no universal number, and degradation isn't always visible. Treat an old or mishandled vial as compromised — see the safety guide.
Do peptides cause cancer?
There's no blanket answer — it depends on the specific compound and its mechanism. Some growth-signalling peptides (GH secretagogues, IGF-1 pathway) raise theoretical concerns about promoting existing growth, which is why a personal or family cancer history changes the risk picture. Most research peptides simply lack the long-term human data to answer this — which is itself the honest answer: unknown.
What about peptides for weight loss?
The strongest evidence by far is for the approved GLP-1 / dual-agonist drugs (semaglutide, tirzepatide), with large human trials behind them. Most other “weight-loss peptides” marketed online have thin or preclinical-only evidence. The tier board ranks them by what's published so you can see the gap between hype and data.
Sources
- [1]Teichman SL et al. — Prolonged stimulation of GH and IGF-1 secretion by CJC-1295 in healthy adults — J Clin Endocrinol Metab, 2006
- [2]EGRIFTA (tesamorelin) — FDA prescribing information — U.S. FDA / DailyMed
- [3]Wegovy (semaglutide) — FDA prescribing information — U.S. FDA / DailyMed
- [4]Mounjaro / Zepbound (tirzepatide) — FDA prescribing information — U.S. FDA / DailyMed
- [5]Compounding bulk drug substances under Section 503A — FDA guidance — U.S. FDA
- [6]BPC-157 — peer-reviewed literature (search PubMed) — PubMed / NCBI
Links resolve to authoritative search or landing pages (PubMed, FDA / DailyMed). See the full source library and methodology.
Track your protocol in PepCue
Log doses, run the calculators, follow the evidence, and keep peptides, GLP-1s, TRT and labs in one private timeline.
Start here →Educational and research reference only. Not medical advice, diagnosis, or dosing guidance.