Guardian review finds many online pharmacies flouting strict advertising rules that govern prescription-only drugs

Weight-loss injections are being aggressively marketed to British consumers through often illegal promotions, in a practice experts have described as a “wild west” industry of drug selling.

The booming market for jabs such as Wegovy and Mounjaro has triggered a price battle among online pharmacies, with even high-street chains cashing in on the soaring demand.

Supermarkets are using loopholes in the rules by advertising discount deals for weight-loss “services” that include – and prominently feature – the injections.

The Advertising Standards Authority (ASA) is preparing to launch an investigation into the marketing of weight-loss injections.

The regulatory body responsible for drug advertising has upheld complaints against online ads for weight-loss drugs every month since April 2023.