Peptide marketing works by borrowing credibility across a category. Semaglutide is a peptide and it has cardiovascular outcome trials; BPC-157 is also a peptide and it has none. Both get described with the same word, and the word carries the reputation of the first to the second.

A peptide is a short chain of amino acids — shorter than a protein, longer than a single amino acid. That is the whole definition. It says nothing about whether something works, whether it is legal, or what is in the vial.

Peptides that are approved medicines

These have gone through trials measuring outcomes, carry a licensed manufacturer, and are prescribed with monitoring.

Semaglutide and tirzepatide

Peptide drugs for type 2 diabetes and weight management, with trials measuring weight, cardiovascular events and kidney outcomes rather than hormone levels. See our guide to GLP-1 drugs.

Bremelanotide

Approved as Vyleesi for hypoactive sexual desire disorder in premenopausal women. The same molecule is sold as PT-141 in research vials — a clear illustration that the molecule and the product are different things.

Teriparatide and abaloparatide

Peptide analogues used to build bone in osteoporosis, with fracture-reduction data. See abaloparatide.

Peptides used in endometriosis, fibroids and some cancers, in use for decades with a well-characterised side-effect profile.

Peptides sold without approval

These are marketed through wellness clinics and online retailers. None has approval for the uses being sold.

CJC-1295 and ipamorelin

Growth-hormone secretagogues, usually sold together. They raise growth hormone; no trial has shown that this improves body composition, sleep or recovery in healthy adults. The FDA placed both in the category of bulk substances presenting significant safety risks for compounding. See CJC-1295.

BPC-157

Marketed for gut healing and injury recovery on the basis of rodent studies. There are no published human trials. It is prohibited by the World Anti-Doping Agency and is in the same FDA compounding category.

Sermorelin

The partial exception. It was genuinely approved once, for growth hormone deficiency in children, and withdrawn for commercial reasons. That gives it a documented safety profile the others lack — but not evidence for the adult wellness uses it is now sold for. See sermorelin.

Melanotan II

Sold for tanning and libido. Case reports document changes in moles and melanoma diagnosed after use. There is no legitimate supply chain for it.

What the FDA did in 2023, and why it matters

Compounding pharmacies can prepare drugs that are not commercially available, which is how many clinics supplied peptides. In 2023 the FDA reviewed substances nominated for that use and placed a number of peptides — including CJC-1295, ipamorelin and BPC-157 — in Category 2: bulk drug substances presenting significant safety risks. The cited concerns were potential immunogenicity, absence of safety data and no established effective dose.

Practically, that closes the most defensible supply route. What remains is research-chemical sellers, which is a step down in every respect that matters.

Why research-grade vials are the real risk

The pharmacology debate is secondary to a simpler problem: you cannot know what you are injecting.

  • Identity and quantity. Independent testing has repeatedly found peptide products that do not match their labels — wrong amount, degraded material, or a different compound.
  • Sterility. These are injected products supplied as powder for the buyer to reconstitute. Nothing certifies the filling conditions, and home reconstitution adds its own risk.
  • Dose. No dose-finding trial was completed, so protocols circulating online are conventions rather than evidence.
  • No monitoring. Nobody is measuring your IGF-1, your glucose or your blood pressure.

Questions worth asking a peptide clinic

  • Is this FDA-approved for what you are prescribing it for? If the answer is a description of compounding, the answer is no.
  • What will you measure before and after? For growth hormone peptides that means IGF-1. No measurement means no way to know anything happened.
  • What result would count as failure? A treatment with no failure condition is not being evaluated.
  • Which pharmacy prepares it, and under which regulation? A 503B outsourcing facility is a real answer; "our supplier" is not.
  • What is the plan if nothing changes in three months? Worth agreeing before the first invoice.

What women are usually trying to fix

Most people arrive at peptides with a specific problem, and each of these has interventions measured against the outcome rather than against a hormone level.

  • Muscle and strength after 50: resistance training and protein at 1.2–1.6 g/kg — see muscle loss in menopause.
  • Weight: the GLP-1 drugs are peptides with outcome trials, and they are prescription drugs for a reason.
  • Low desire: pain, medication and sleep account for most of it — see low libido.
  • Sleep: exclude sleep apnea and night sweats first — see menopause insomnia.
  • Bone: if fracture risk is the concern, approved anabolic drugs exist — see osteoporosis medications compared.

We do not publish dosing protocols or sourcing guidance for unapproved peptides. There is no established safe dose to give and no way to verify a vial bought online.