‘Traceability Is Vital’: Labs Test Thousands of Unregulated Substances Amid Peptide Craze

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.

Peptides are short chains of amino acids. These can be found naturally in the body – for example hormones, such as insulin, oxytocin and vasopressin are peptides – but they can also be made synthetically in the laboratory.

They include the active ingredients in prescription weight-loss drugs, such as Wegovy, which mimic the natural hormone GLP-1, as well as in experimental compounds pushed online by the booming biohacking and anti-ageing industries. On Telegram and TikTok, users claim the injections can heal injuries, sharpen focus and smooth wrinkles.