While the number of reported cannabis poisonings in Australia have surged in the last 10 years, researchers are not linking the rise to the legalisation of medicinal use.
A team from the University of Sydney analysed data from the New South Wales Poisons Information Centre (NSWPIC), which receives around half of all calls to Australian poisons information centres. The majority of calls came from within NSW (65%), with the rest from other states.
Data was collected between July 2014 and June 2024.
During this time, the NSWPIC received 3,796 calls about cannabis poisoning, increasing by 12.8% per year, with 54% concerning boys or men and 46% relating to girls or women.
The exposed person exhibited symptoms of poisoning at the time of the call in 3,184 cases (84%), while 2,783 people (74%) were in hospital at the time of the call or were referred to hospital.
Intentional cannabis exposures – classed as recreational use, deliberate self-poisoning and other intentional misuse – were reported by 2,981 calls (79%), increasing by 9.2% per year, with unintentional exposures – including therapeutic errors and accidental exploratory exposure – reported by 815 calls (21%), increasing by 30% each year.
The age‐adjusted cannabis poisoning exposure rate was highest among teenagers aged 15 to 19 at 11.4 calls per 100,000 population per year, while the age‐adjusted rate for unintentional exposures was highest for toddlers aged one to four with 1.9 calls per 100,000 population.
Plant‐based cannabis (flower or leaf) was the reported exposure form in 2,663 cases (70%), although the proportion declined from 72% in 2014–15 to 61% in 2023–24.
The proportions of cases involving concentrates and edibles both increased, from 0 to 124 calls (22%), and from nine calls (5%) to 88 (16%) respectively.
Across the decade, concentrates (320 calls, 39%), plant‐based cannabis (302 calls, 37%), and edibles (171 calls, 21%) were the three product forms most frequently involved in unintentional exposure calls.
Calls about exposures to edibles have increased rapidly since 2019–20, particularly gummy or lolly forms (89 cases, all reported since 2019–20).
Despite the numbers, the team could identify no firm reasons for the upward trend – including the legalisation of medicinal use – and speculated it could instead reflect increasing acceptance of cannabis use generally as well as wider access to edibles.
They wrote: “The increase in exposure calls could… reflect a steady increase in cannabis use during 2014–24 because of changing social norms and perceptions of cannabis safety and legality.
“The more rapid increase in calls about exposures in young people could reflect the increasing availability of edible forms, which can be medically prescribed or obtained illicitly.
“This interpretation would be consistent with survey findings that about 15% of Australians who used cannabis for medicinal purposes used oral formulations in 2016 (prior to its legalisation), but 33% did so in 2022–23.”
The researchers said while it is “widely believed” that cannabis is safe in overdose, “it can cause central nervous system (CNS) excitation, CNS depression, hallucinations, psychosis, and cardiac dysrhythmias”.
They added: “The risk of severe toxicity is greater for children, in whom it can lead to apnoea and coma; in one US study, 32 of 60 children (aged 0–10 years) hospitalised with cannabis intoxication required intensive care.”
They also pointed to US studies which have reported increases in the number of poisonings following medicinal and recreational cannabis legalisation, particularly in children.
“Edibles are particularly high risk products because of their palatability and the possibility of large ingestions,” they said.
The team acknowledged limitations in the study including the fact that the NSWPIC does not routinely undertake follow‐up enquiries, the relatively low numbers in the data set and its self-reporting nature.
Some exposures were also due to the ingestion of multiple substances.
