An investigation by the Sheffield Tribune has exposed an underground market for unlicensed "peptide" drugs in the city, with unapproved substances such as Retatrutide being injected by residents ranging from menopausal women to students seeking weight loss or performance gains. The trade, described by one gym owner as "a massive, massive industry" that has overtaken steroids, is largely unregulated, with sellers operating via Facebook Marketplace and WhatsApp and offering little safety oversight — prompting comparisons to "gold rush" opportunists selling shovels rather than striking gold themselves. The UK's medicines regulator has warned that "rogue sellers" are prioritising profit over consumer safety.

The report features Sarah, a 48-year-old cleaner who lost two stone in four months on Retatrutide but suffered six weeks of nausea, headaches and lethargy before continuing the treatment regardless. It also details an unlicensed Crookesmoor dealer known as "Dr Chow," who runs a website-less operation selling 88 different products priced from £5 to several hundred pounds, including a £210 humanin product. By contrast, legitimate NHS-adjacent alternatives such as Mounjaro cost between £125 and £320 a month. In July 2026 the Medicines and Healthcare products Regulatory Agency (MHRA), whose enforcement head Andy Morling gave comment for the piece, issued a public warning about the health risks of buying such peptides outside regulated channels.