Hidden-market sellers promote unlicensed weight-loss drugs through WhatsApp and Telegram giveaways.
They offer injectable medicines like retatrutide as competition prizes.
The Guardian observed groups urging users to enter within 24 hours.
Experts warn these promotions pose serious health risks and bypass medical safeguards.
UK law restricts weight-loss injections to prescription-only supply.
Unapproved drugs like retatrutide cannot be legally sold or advertised.
Telegram and Meta say their platforms prohibit illegal drug sales.
