A national class action has been brought against Aurora Cannabis in Canada, alleging that the company ‘negligently’ failed to warn consumers about the risk of developing Cannabinoid Hyperemesis Syndrome (CHS).
On May 14, 2025, the Ontario Superior Court of Justice certified a national class action alleging that Aurora Cannabis Inc, and Aurora Cannabis Enterprises Inc. negligently failed to warn consumers of the risk of developing CHS posed by the regular use of its products.
The claim is being brought by Sotos Class Actions on behalf of all customers who purchased an Aurora Cannabis product between February 2015 and May 2025, and went on to receive a diagnosis of CHS. It alleges that the company knew, or should have known, of the risk of CHS arising from the regular use of their cannabis products, but failed to provide any warning to consumers or prescribing physicians.
In 2021, the US Surgeon General released a statement warning of the potential risk of CHS in chronic cannabis users. It is usually associated with regular, high-THC cannabis use, characterised by cyclical bouts of severe nausea, vomiting, and abdominal pain, which can persist for several days and occur as often as once every five minutes. In extreme cases, CHS has been linked to fatalities.
However, the lack of standardised diagnostic criteria or routine screening, especially in jurisdictions where cannabis remains illegal, means the real prevalence of CHS is unclear. According to some research, it ranges from 350,000 in the USA, to an extrapolated estimate of 2.75 million, based on data from an emergency department survey in New York City.
According to Margaret Waddell, partner at Sotos Class Actions, thousands of Canadian cannabis users are hospitalised and diagnosed with CHS every year.
“We know from a study that was published in 2022 that over 8,000 individuals had been hospitalised, approximately 19,000 between 2014 – 2021, just in Ontario,” she told Cannabis Health.
“As cannabis was legalised during the study period (in 2018), and use has gone up since widespread commercialisation, the authors of the study estimate a significant increase in CHS, which has been borne out based upon information we have received from ER doctors. We estimate the total number of people who have suffered from CHS during the class period to be approximately 35,000 individuals, and based on Aurora’s market share, we estimate that there are in the range of 5,250 individuals who would qualify as class members in the claim against Aurora.”
“Manufacturers should have been warning consumers about CHS”
The action was commenced by a Canadian Armed Forces veteran, known as V.T, who was prescribed cannabis to treat medical conditions.
After purchasing medicinal cannabis from Aurora and using it as prescribed, she is said to have experienced two extreme bouts of nausea, vomiting and abdominal pain for which she was hospitalised. On a second visit to the emergency room, she was diagnosed with CHS. V.T stopped consuming cannabis, the only known treatment for CHS, and is now understood to be symptom-free.
“V.T commenced this action to help draw awareness to the fact that consuming cannabis products can cause CHS. She does not want other people to suffer the way that she did when the CHS manifested itself,” said Waddell.
“She would like to see Aurora (and other cannabis producers) include a warning about the risk of CHS, so that consumers are properly informed about the risk, and so that if they do suffer from CHS, they will be better able to identify what has happened, and know how to treat the symptoms.”
According to the claimants, none of the cannabis products that were consumed contained any warning about CHS, nor is there any warning in the product monograph or on Aurora’s website.
“CHS has been identified in scientific journals since 2004, and in our opinion, the manufacturer should have known about this side effect of regular use once it was identified, and certainly by the start of the class period in this case, CHS was well-recognised in the scientific community,” Waddell continued.
“Our opinion is that the manufacturers and distributors should have been warning consumers about CHS, just as they warn about other adverse effects, so that consumers can make informed decisions about use, continuing use, and how to respond if they develop CHS.”
Dr Benjamin Caplan, an experienced cannabis clinician and author of The Doctor-Approved Cannabis Handbook, agrees that there is not enough guidance around CHS for consumers or prescribing clinicians.
“For most medical cannabis users—especially those taking moderate doses of balanced or CBD-rich products—the risk of CHS is extremely low. But for daily, high-THC users, particularly those using concentrates like wax or distillates, it’s a legitimate concern,” he tells Cannabis Health.
“Physicians often confuse it with withdrawal, cyclic vomiting syndrome, or just assume it’s unrelated to cannabis at all. Tthere are no national guidelines, no CME credits dedicated to it, and no real infrastructure for educating prescribers on how to prevent or manage it.
“We need better education, clearer diagnostic pathways, and most of all, more real-world clinical experience to make sense of it all. Fear-mongering doesn’t help—but silence isn’t working either.”
A “bellwether” moment for cannabis?
This is thought to be the first time such a legal case has been brought against a cannabis company, but both Waddell and Caplan believe it could have knock-on effects for the industry as a whole.
“The Aurora case could be a bellwether moment,” says Caplan.
“Not necessarily because of the strength of the claim—time will tell on that—but because it marks a shift in consumer expectations. Cannabis is being pulled into the same legal and ethical standards that govern pharmaceuticals and supplements. That’s not a bad thing.”
Waddell is certainly hoping that it may lead to legislative changes requiring “more robust warnings” for Canadian consumers, including the inclusion of CHS in the product monograph.
“It is possible that more class actions will be commenced against other cannabis manufacturers,” she adds.
“We are certainly interested in speaking to anyone else who would be interested in starting a class action against any of the other Canadian manufacturers to discuss what is involved.”
Aurora Cannabis denies all the claims made against it.
A spokesperson for the company said: “It is the Company’s practice not to comment on legal matters beyond information that is made available to the public. Information pertaining to the mentioned class action can be obtained through our standard disclosures.”
The post Aurora Cannabis Faces Class Action Over Lack of Warnings About Cannabinoid Hyperemesis Syndrome appeared first on Cannabis Health News.
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Author: Sarah Sinclair
