The ASA has today published new consumer research alongside a CAP Enforcement Report on how weight-loss prescription-only medicines are being promoted to the public and the steps we’re taking to protect people from harmful ads.

Our research shows that growing public interest in weight-loss medicines, combined with increasingly sophisticated marketing, is creating new risks in the weight-loss advertising landscape.

Many people interpret ads for weight-loss treatments as promoting prescription-only medicines, and some feel pressure to pursue treatments that require proper medical oversight.

Our enforcement update outlines how we’re responding to these risks and the action we're taking to keep consumers safe.

What the research shows

Public interest in weight-loss medicines is exceptionally high. Our research shows that people have significant knowledge of – and interest in – these treatments, which shapes how they understand and interpret ads.

Seventy-one per cent of the UK audience have functional or high knowledge of these products. Six per cent of the UK population have used them before and a further 18% would consider using them in the future.

Many participants viewed the tested ads as encouraging purchases rather than medical consultations. Most people also felt that weight-loss treatment ads put pressure on people to lose weight and are often targeted at vulnerable audiences. Women – who are most frequently targeted – reported feeling particular pressure to lose weight.

At the same time, many people do not realise that weight-loss injections are prescription-only medicines. Some see them as medical treatments, while others view them as lifestyle tools available to anyone. Signals such as images of injector pens and references to “jabs”, “pens” or BMI (body mass index) eligibility were strongly associated with weight-loss injections. People with greater familiarity with these medicines are more likely to interpret the ads as promoting them.

These insights help inform our regulatory approach, as industry practices evolve and new products enter the market.

Strong progress, but more to do

Over the past year, the ASA and CAP have carried out extensive monitoring, investigation and enforcement. The ASA has published 18 rulings since 2025 on advertising for services providing these medicines.

CAP has also taken sustained compliance action, including a jointly published Enforcement Notice with the Medicines & Healthcare products Regulatory Agency (MHRA) and the General Pharmaceutical Council (GPhC) in September 2025, updated guidance clarifying how the rules apply, and direct engagement with advertisers in the sector.

Using our AI-driven Active Ad Monitoring system, we’ve captured and assessed tens of thousands of weight-loss ads from high priority advertisers. We are now publishing a CAP Enforcement Report setting out the impact of this work.

We identified around 900 ads likely to breach the rules, from 38 of the 44 advertisers monitored. The most common problems included:

• Naming a prescription-only medicine, for example Wegovy, Mounjaro or Ozempic
• Using descriptors clearly understood as references to prescription-only medicine such as “weight-loss injection”, “pen”, “jab” or “GLP1”
• Featuring images of branded injection pens

Following targeted action, compliance with the Enforcement Notice now stands at around 99% among monitored paid-for ads. This shows strong progress following enforcement action.

Our partnership with the MHRA and GPhC has strengthened consistency across regulators and supporting action against persistent breaches.

However, challenges remain. Non-paid content, especially influencer and affiliate advertising, presents a higher risk of non-compliance. We are also seeing emerging “grey area” approaches, such as promotional pricing, where the ASA is conducting ongoing investigations.

What this means for the public

The law prohibits advertising prescription-only medicines to the public for good reason: these are powerful drugs that require clinical assessment and ongoing medical supervision.

Yet our research shows that many consumers are unaware that these medicines require a prescription, which affects how they interpret ads.

Strong public interest, rapidly expanding knowledge and a complex advertising landscape increase the risk that people perceive ads as promoting prescription-only medicines or feel placed under undue pressure.

Our role is to intervene early, set clear expectations for advertisers and ensure protections keep pace with evolving marketing practices.

What next?

The publication of our consumer research and Enforcement Report is a key milestone in our ongoing programme of work.

In 2026, we will:

• Continue monitoring and enforcement, including issuing new rulings where precedent is still developing
• Engage further with industry to ensure advertisers understand their responsibilities and comply with the law and our rules
• Work closely with the MHRA and GPhC to stay ahead of emerging advertising risks

Our focus remains on supporting responsible businesses and ensuring the public are protected as this market evolves.

 

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