An application has been filed in Quebec to obtain authorization to institute a class action concerning the drugs Mounjaro, Trulicity, and Zepbound, alleging that the widely used diabetes and weight-loss medications may expose patients to serious health risks that were not adequately disclosed. On December 23, 2025, Siskinds LLP’s Quebec affiliate, Siskinds Desmeules, applied to the Superior Court of Quebec for authorization to bring a case on behalf of Quebec residents who were prescribed and used GLP-1 receptor agonists and experienced serious health problems.
The lawsuit targets Eli Lilly and Company and its Canadian subsidiary, alleging their liability as manufacturers and for other breaches, arguing that they failed to properly warn patients and healthcare providers about serious known or foreseeable risks posed by the active ingredients in the drugs, dulaglutide and tirzepatide. According to the claim, the drugs were marketed as safe and effective without sufficient disclosure of potentially severe side effects, preventing patients and physicians from making fully informed treatment decisions.
What are GLP-1 receptor agonist drugs?
Trulicity (which contains dulaglutide), along with Mounjaro and Zepbound (both of which contain tirzepatide), belong to a class of medications known as GLP-1 receptor agonists (GLP-1 RAs). This class also includes Ozempic. GLP-1 RAs, such as dulaglutide and tirzepatide, work by mimicking natural hormones that help regulate blood sugar, slow digestion, and reduce appetite.
Trulicity and Mounjaro are approved in Canada to treat type 2 diabetes, while Zepbound is approved for long-term weight management.
Health risks alleged in the lawsuit
The Quebec application alleges that dulaglutide and tirzepatide are linked to a range of serious medical conditions that were not sufficiently disclosed. These include gallbladder disorders (such as gallstones), severe gastrointestinal injuries (including gastroparesis, or “stomach paralysis”), blood clots, aspiration during surgery, necrotizing pancreatitis, malnutrition, and a unique form of vision loss known as non-arteritic anterior ischemic optic neuropathy (NAION).
The claim alleges that by slowing digestion and altering hormonal processes, the drugs can cause organ dysfunction, poor nutrient absorption, and irregular blood flow, leading to hospitalizations, surgeries, and lasting physical harms. The lawsuit asserts that Eli Lilly knew or should have known of the risks based on scientific studies, adverse-event reports, and regulatory reviews.
Alleged lack of proper warnings
A key allegation is that Canadian product monographs failed to sufficiently warn of the risks. The claim states that warnings emphasized mild digestive discomfort while omitting clear descriptions of severe conditions such as gastroparesis. It further alleges that stronger warnings appeared earlier in the U.S. and that none of the Canadian monographs include a “black box” warning for the risks. The lawsuit also alleges aggressive, misleading marketing through ads and social media.
If authorized, the class action will seek compensation for physical, emotional, and financial harms suffered by class members.
Siskinds is pursuing justice for Mounjaro/Trulicity/Zepbound users who were harmed
Siskinds LLP is seeking to recover compensation for Canadians who suffered injuries after taking prescription Mounjaro, Trulicity, and Zepbound, or other GLP-1 RAs, like Ozempic. If you or someone you know used a GLP-1 drug and were harmed, email [email protected], call 1-800-461-6166, or visit GLP-1 drugs class action landing page and complete the form at the bottom of the page.