You may have seen this article or some other article yesterday or today, covering the Ontario Supreme Court's recent certification of a national class action lawsuit against Aurora Cannabis. The defendant entities are all part of the same conglomerate, with Aurora Cannabis Inc. being the parent. You can view their vast array of cannabis products here.
Aside from securities litigation, class action lawsuits seldom drop in the cannabis space. So this one got me thinking. Below are some thoughts in Q&A format.
What does the Canadian lawsuit claim?
Here is the Statement of Claim. In short, the complaint is that the defendants negligently failed to warn consumers, patients and their treating professionals of the risk of developing cannabis hyperemesis syndrome (CHS). This risk was allegedly posed by the plaintiffs' ordinary use of the defendants' cannabis products.
In addition to alleging negligence, the plaintiffs allege breach of consumer protection statutes and, somewhat awkwardly, unjust enrichment. According a claim summary, the defendants' failure "is alleged to be particularly egregious given that cannabis products are often recommended by healthcare professionals to treat nausea, which paradoxically is a common symptom of CHS."
What exactly is cannabinoid hyperemesis syndrome?
Qualified sources define CHS as: 1) a "syndrome of cyclic vomiting associated with cannabis use"; and as 2) "characterized by cyclical episodes of nausea and vomiting, accompanied by abdominal pain following prolonged, high-dose cannabis use, which is alleviated by hot baths and showers." Interestingly, the latter source observes that "little is known about the cause of this syndrome."
Here, too, is a 2025 National Library of Medicine journal abstract on the topic, with a similar definitional and etiological take, and adding this noteworthy fact: "Although considered rare, there has been a steady increase in CHS diagnoses. . . .." Whether that means CHS is actually occurring more frequently is another question.
Why did Aurora not include CHS warnings?
Hard to say. The lawsuit alleges that "[t]he Defendants knew or ought to have known of all the serious harmful effects arising from the consumption of their Cannabis Products." If that's right, a cynical answer is that warnings weren't given because sales would have suffered.
It's also likely, though, that warnings weren't given because they are not required by Health Canada regulations or the Cannabis Act. Here, it's worth noting that cannabis packaging rules in Canada are quite strict and comprehensive, and they do require other "health warning messages." These include warnings about overconsumption leading to "cannabis poisoning" and "severe anxiety and panic attacks." But warnings related to CHS are not required.
So should these plaintiffs instead be suing the government?
Probably not. Getting damages from a government is generally harder—much harder— than getting damages from a private party. Governments and public officials have so much immunity.
The fact that Canadian laws do not require CHS-related disclosures is important, though. You can expect the defendants to argue that they strictly complied with all packaging and labeling requirements with respect to the allegedly hazardous, heavily regulated products—including giving all requisite health warnings. If you buttress that argument with the "unclear etiology" piece, and the fact that CHS diagnoses are still rare, and the fact that some of these plaintiffs appeared to have professional medical advisers, it starts to look pretty good.
Could other health claims follow?
Possibly. Like the U.S., Canada utilizes the DSM-5, which lists cannabis use disorder ("CUD") among its diagnosable mental health conditions. The DSM-5 defines CUD as "the presence of clinically significant impairment or distress in 12 months, manifested by at least two of a series of symptoms or behaviors." You can see the definition and full list of symptoms/behaviors here.
The fact that the defendants are being sued for knowingly causing CHS makes it seem just as likely they could be sued for knowingly causing CUD— another adverse, cannabis-related health outcome that is seemingly better understood and established than CHS. The defendants don't appear to be warning about either affliction. I wonder if anyone is.
What does this mean for U.S. cannabis companies?
The U.S. is much different than Canada in that cannabis is federally prohibited. All U.S. regulations around cannabis provision and sale—including those around packaging, labeling and warnings—are left to the states. If U.S. "copycat" lawsuits ensue, they would be on a state-by-state basis, implicating state law claims.
As with Health Canada, though, U.S. states that permit cannabis sales have strict (and onerous) packaging and labeling requirements. If a company wanted to be very careful, it could start including warnings about CHS and CUD on its labels, but only if a) it could afford to go through the label re-creation and re-approval process, and b) there were any space!
Daniel Smith at Strategies 64 had a nice piece this week called "the Future of Cannabis Labeling is Digital", where he summarizes all of the challenges and confusion around cannabis labeling requirements among the many states, and offers that:
"the most practical way to modernize and improve cannabis labeling is to leverage QR codes or similar technology, which allow consumers to access websites or other online resources by scanning a code on the product."
With unlimited space, it would be much easier for cannabis companies to issue prophylactic statements on CHS or CUD, or whatever—even if the regulations don't require it. One interesting argument in the CHS lawsuit, after all, is:
"while the defendants maintain websites that provide information about the Cannabis Products to consumers and prescribing physicians, these websites do not warn of or even mention the risk of CHS. The Defendants do not publish product monographs for the Cannabis Products . . . . communicating the risk of CHS."
This seems like one of those cases where a bit of fine print would have gone a long way.
What will happen next?
We may see some cautious operators north and south of the border start to place CHS, CUD and/or additional health-related disclaimers on their websites or labels, with the typically required driving- and pregnancy-oriented statements.
As far as this particular lawsuit, I don't know Canadian law and I'm not a litigator—much less a class action pro. The plaintiffs are currently seeking to build out their potentially large class after clearing the sizable certification hurdle. So whatever ends up happening will probably take a while.
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