Approval status is the first filter
A small number of peptides — semaglutide, tirzepatide, tesamorelin, bremelanotide — have gone through full clinical trials and regulatory approval. Everything else is sold as a 'research chemical', which is a legal category, not a quality standard.
Research-chemical status means nobody has verified purity, sterility, dosing or long-term safety for the vial you receive. Third-party certificates of analysis help, but they can be fabricated and they only describe one batch.
Reading study quality
Most peptide marketing cites rodent studies. A result in mice is a hypothesis about humans, not evidence of a human effect. Ask three questions of any claim: was it in humans, was it randomised and placebo-controlled, and was it replicated?
- Strong — multiple randomised human trials, regulatory review
- Moderate — human pharmacokinetic or small clinical data
- Emerging — strong preclinical work, human data starting
- Limited — animal or in-vitro only, or old unreplicated studies
Risks that are frequently understated
Beyond the specific side effects of each compound, four risks apply broadly:
- Contamination and mislabelling from unregulated suppliers, including bacterial endotoxin
- Angiogenic and growth-promoting peptides potentially feeding undiagnosed tumours
- Endocrine disruption from sustained interference with feedback loops
- Non-sterile injection technique causing abscesses or systemic infection
Who should not use peptides
Anyone with a personal or family history of cancer should treat growth-promoting and angiogenic peptides as off the table without oncology input. Pregnancy and breastfeeding rule out essentially all of them. If you take prescription medication, interactions with GLP-1 agonists in particular — which slow gastric emptying and therefore drug absorption — need a pharmacist's review.
Competing athletes should assume any peptide on this site is banned by WADA unless they have verified otherwise.