‘Traceability is vital’: labs test thousands of unregulated substances amid peptide craze

Experts warn consumers of unknown risks as one lab says about a third of samples fail basic quality checks

• What are peptides, are they safe and is there evidence to back up the hype?

• Is a new weight-loss drug making people fall out of love?

People in the UK are sending thousands of unregulated substances that claim to support weight-loss and wellness to laboratories for testing, as experts say the underground market for injectable peptides has exploded.

The peptide-testing industry has expanded rapidly alongside demand for these substances, with one lab telling the Guardian that a decade ago, they handled a handful of tests a month sent by customers and vendors around the world to check what was in them. Today, they process around 60,000 samples a year, including roughly 2,000 orders from the UK since 2024.