WITH 4/20 Day coming up, an unofficial day associated with cannabis use, researchers from the BC Children’s Hospital Research Institute are urging parents and caregivers to talk to their teens about the risks of cannabis poisoning.

A recent study comparing emergency department visits to BC Children’s Hospital before and after cannabis was legalized in Canada found that in both cases, the majority of cannabis-related visits to the emergency department were from intentional use among youth 14 to 16 years-old. In other words, youth knew they were using cannabis, but used too much.

From January 2016 to December 2018—the three-year period before legalization—the number of emergency department visits for cannabis poisoning increased each year among all children and youth, with a total of 119 cases during this time period. In the three-month period immediately after legalization, there was an immediate further increase in cases. The number of visits then decreased each year from January 2019 to December 2021—the three-year period after legalization—but the total number of cases was higher than pre-legalization at 185 cases.

The reason for the increase immediately following legalization is unknown. It could be due to population changes, or increased prevalence of cannabis products in the home after legalization. The observed decrease may be related to changes in healthcare-seeking behaviour during the COVID-19 pandemic, when individuals were less likely to visit the hospital for milder poisoning cases due to social distancing.

Over half of cannabis poisoning cases among youth occurred while the individual was among their peers. Nearly all youth were treated or observed in the emergency department and discharged. A small number required further monitoring in hospital before being sent home; there were no deaths related to cannabis poisoning.

Among youth, the median (middle) age for poisoning was 15-years-old. In British Columbia, the legal age of cannabis use is 19-years-old. After legalization, male youth were more likely to just use cannabis, whereas female youth were more likely to co-consume cannabis with other substances, such as alcohol, illicit drugs, or medications. Inhalation was the most common form of cannabis consumption among youth.

Symptoms of cannabis poisoning include vomiting, confusion, dizziness, slurred speech, slowed breathing, and unresponsiveness. Rare and serious cases can result in a coma and seizures.

“Our study found that despite being below the legal age limit for cannabis use, teens are still smoking and ingesting cannabis products,” said Dr. Shelina Babul, director, BC Injury Research and Prevention Unit at BC Children’s Hospital Research Institute. “Although cannabis poisonings rarely have life-threatening effects, we want to remind parents to have conversations with their teenagers about refraining from using cannabis, and if the teens choose to do so, to use it safely.”

The study authors have the following tips for parents and caregivers:

• Have a conversation with your teens about cannabis use, health risks, symptoms of cannabis poisonings, and harm reduction behaviours.
• Recognize the signs of cannabis poisoning so you can intervene as a bystander, if it’s safe to do so.
• If you suspect symptoms of cannabis poisoning, call the BC Drug and Poison Information Centre at 1-800-567-8911. If someone is having difficulty breathing, call 9-1-1.
• Reaction times are slowed when under the influence of cannabis. Remind your teen that they should not be driving, cycling, or using any mobile form of transportation after consuming cannabis.
• As young children often cannot tell the difference between cannabis and non-cannabis products, store cannabis products high up, out of reach, and preferably in a locked container or drawer.

The study was published in the April edition of the journal Health Promotion and Chronic Disease Prevention in Canada. The study used data from the BC Children’s Hospital Canadian Hospitals Injury Reporting and Prevention Program (CHIRPP), a national injury and poisoning surveillance system that collects and analyzes data on injuries. CHIRPP is a program of the Public Health Agency of Canada.

Learn more:

• Link to full study: https://doi.org/10.24095/hpcdp.46.4.04
• Link to blogpost: https://www.injuryresearch.bc.ca/news/cannabis-study-bcch-2026
• Factsheet on cannabis poisoning (BCIRPU): https://bit.ly/cannabisBCCH