Hidden sellers promote unlicensed weight-loss drugs through WhatsApp and Telegram giveaways.
They offer powerful injectable medicines as competition prizes.
The Guardian found groups advertising retatrutide, an experimental drug without approval.
Posts pressure users to enter within 24 hours.
Experts warn these promotions pose serious health risks.
They say marketers misuse social media tactics for unlicensed medicines.
One group offered retatrutide, Glow pens, and melanotan II as prizes.
None of these injectable products hold UK approval.
UK law allows weight-loss injections only with valid prescriptions.
Unapproved drugs cannot be legally sold or advertised.
Another seller disguises drug sales as fitness coaching programmes.
Researchers warn these tactics bypass safeguards and endanger users.
