Lilly and Novo take the copycat fight to the National Advertising Division

Eli Lilly and Novo Nordisk are using a new tool against sellers of copycat GLP-1 drugs: advertising challenges filed with BBB National Programs' National Advertising Division, a self-regulatory body that resolves disputes over ad claims. Over the past year the two drugmakers have filed 10 cases there against compounders and telehealth companies, Bloomberg Law reported ^[1].

The NAD route sits alongside a much larger legal campaign. Novo Nordisk said it has filed 130 federal lawsuits and five NAD challenges ^[1][2]. Lilly has filed dozens of federal lawsuits and at least five NAD cases ^[1][2]. A Novo spokesperson said the company "will continue to work with law enforcement and regulators to help address illegal activity" and called NAD "an important forum to bring complaints against companies making false and misleading claims about unapproved compounded drugs" ^[1]. Lilly described the division as "an independent authority whose mission is to build consumer trust in advertising" ^[1]. The companies challenged by Novo or Lilly did not respond to Bloomberg Law's requests for comment ^[1].

How the NAD process works

NAD has existed since 1971 and has handled disputes over everything from bathroom cleaners to infant formula ^[1]. Unlike a lawsuit, the burden falls on the advertiser to show it has a reasonable basis for the claim being challenged ^[1]. An attorney reviews the case, confers with both sides during a briefing period, and drafts a decision or recommendation ^[1]. Decisions can be appealed to a board of academics and brand representatives ^[1].

The process is voluntary. An advertiser does not have to participate or follow the recommendations, and NAD has no legal authority ^[1]. But it can refer a matter to regulators including the FDA, the Federal Trade Commission, or state attorneys general, and it can report the ad to the social media platforms where it runs ^[1]. Resolution generally takes months rather than years, said Ricardo Carvajal, a director at Hyman, Phelps & McNamara who represents advertisers ^[1].

Two recent cases show the pattern. In December 2025, Novo's challenge led NAD to find that Texas telehealth company Willow Health Services made unsubstantiated safety, efficacy and superiority claims for its compounded semaglutide ^[2]. Willow did not say whether it would comply, so NAD referred the matter to the FTC, state attorneys general and the ad platforms ^[2]. Willow later returned to NAD after discussions with the FTC, and in July 2026 NAD confirmed the company had permanently discontinued all challenged claims, including ones about comparability to FDA-approved semaglutide and effectiveness without diet or exercise ^[1][2]. In May 2026, Lilly challenged Noom's tagline "A Smaller Dose. A Smarter Start. Microdose GLP-1Rx Starts at $119" ^[2]. NAD found the claim implied, without support, that a smaller dose itself delivered a measurable health benefit ^[2]. Noom disagreed but agreed to modify or drop the claim, and separately said it was permanently discontinuing other challenged claims about dosing, efficacy and side effects ^[1][2].

Why it matters for patients

The practical effect is on what patients read before they buy. Compounded drug ads cannot be false or misleading under federal law, but they do not go through the same government review as ads for brand-name drugs ^[1]. When a compounder or telehealth site drops claims that its product is comparable to FDA-approved semaglutide, or that it works without diet and exercise, those specific selling points disappear from the marketing ^[2].

Context matters here. The FDA determined that branded GLP-1s are now available after a shortage period, which effectively bars mass production of cheaper copies that Bloomberg Law reports have been used by at least a million patients ^[1]. Compounders still make personalized versions ^[1]. The FDA has sent more than 100 warning letters in the last year over misbranded compounded GLP-1 claims, but that enforcement has stayed narrow, focused on issues such as active ingredients, branding and product performance ^[1][2].

Ashwin Chetty, a medical student at Yale School of Medicine who studied compounded GLP-1 ads, told Bloomberg Law that enforcement "has really been focused on what these websites shouldn't say," and argued there should also be guidance on what they should be saying ^[1]. In other words, removing a misleading claim does not automatically mean a site gives patients complete information.

The financial stakes are large. Lilly's tirzepatide franchise (Mounjaro and Zepbound) reached $40 billion in sales, while Novo's semaglutide products (Ozempic, Wegovy, Rybelsus) generated $35 billion last year ^[1].

What happens next

The fight is not one-directional. In January 2026, Strive Compounding Pharmacy filed a federal antitrust suit against both Lilly and Novo in the Western District of Texas, alleging the drugmakers used exclusive agreements with telehealth platforms to bar those platforms from working with compounding pharmacies ^[2]. The sources do not say how that case has been resolved, or how many more NAD challenges the companies plan to file.