How to Source Peptides Safely
The peptide market is unregulated and full of low-quality or mislabeled product. Here’s how to vet a vendor, the red flags to walk away from, and where we recommend starting.
Where we recommend starting
Two suppliers we’re comfortable sending people to: PeptGenX and PSPeptides. Both publish third-party COAs and sell for research use only. “Where to Buy” links are affiliate (we may earn a commission at no cost to you); that never affects our scores or which peptides we cover. Code THS10 works at both stores — on PeptGenX it lands in your cart automatically; at PSPeptides enter it at checkout.
Shop PeptGenXThe vendor-vetting checklist
- Third-party COA for every batch, testing identity + purity (+ ideally endotoxin/microbes).
- Physical address + real contact info, not a contact form to nowhere.
- Transparent policies — returns, reshipping, and a clear stance on quality issues.
- Consistent independent reviews over time (Reddit, forums) — not just on-site testimonials.
- Sells “for research only,” not dosing instructions or medical claims (a legal + safety signal).
Red flags — walk away
- No COA, or a COA from the seller’s own lab with no third-party verification.
- Medical or miracle claims (“cures X,” “FDA-approved” for a research peptide).
- Prices dramatically below the market — usually means under-dosed or mislabeled product.
- Crypto-only, no refund path, or a brand-new domain with no track record.
- Pushy dosing advice from the seller (they have a conflict of interest).
GLP-1s are different
Semaglutide and tirzepatide are FDA-approved medicines, not research peptides. The safe path is a licensed prescriber or a regulated pharmacy — not a gray-market vendor. See the semaglutide and tirzepatide pages for the sourced detail.
Next
Before you buy, read Safety & Side Effects — and get the free cheat-sheet by email below for quick reference. And when a seller says it’s “FDA-registered”: that’s not approval — here’s the difference and the 2-minute check.