Significant drop in cannabis-related adverse reaction reportsCanada

Key highlights

In 2023, Health Canada received 128 reportsFootnote 1 of adverse reaction reports (including duplicates, such as multiple reporters of the same adverse reaction) associated with cannabis as a suspected substance.

Out of the 128 reports, 56 were unique casesFootnote 2 associated with legal cannabis products.

Of the 56 unique cases involving legal cannabis products:

• 45% involved females and 39% involved males
• 59% involved cannabis used for medical purposes (self-reported)
• 64% involved cannabis extracts
• 27% of cases involved adults aged 18 to 44 years and 23% were missing age-related information
• 52% of cases were reported as serious, with other (medically important condition) as the most frequently reported reason for seriousness

207 adverse events reported across the 56 unique cases were assessed for causality; 96 were deemed to be certainly, probably or possibly related to the suspect cannabis product(s). The most frequently reported adverse events across all cases involving legal cannabis products where a causal relationship was determined included:

• headache (n=7)
• vomiting (n=5)
• dizziness (n=5)
• agitation (n=3)
• loss of consciousness (n=3)
• anxiety (n=3)

In 2023, there were no suspected cases of vaping-associated lung injury (VALI).

Most findings have remained consistent from 2022 to 2023, however, some changes were observed, namely:

• a decrease in the total number of cases (serious and non-serious)
• a shift in some of the reasons for seriousness being selected by reporters
• the types of adverse events reported, and, in some instances, the type of individuals involved in adverse reaction cases (for example, the distribution of sex)

Health Canada continues to monitor, assess and report on adverse reactions associated with cannabis, and findings continue to be used to prepare evidence-based educational materials on health and safety risks with cannabis, including risk communications and educational resources.

Introduction

This report describes the findings of the domestic case reports of adverse reactions associated with cannabis submitted to Health Canada's Canada Vigilance database and analyzed by the Office of Cannabis Science and Surveillance of the Controlled Substances and Cannabis Branch in Health Canada. This work forms part of the Vigilance Framework for Cannabis that has been in place since the coming into force of the Cannabis Act and Cannabis Regulations (October 17, 2018).

This annual data report presents a summary of all domestic case reports of adverse reactions submitted to Health Canada between January 1, 2023, and December 31, 2023, suspected of being associated with a cannabis product as defined under the Cannabis Act or its Regulations, intended for human consumption.

For the purposes of this report:

• A legal cannabis product means cannabis of 1 of the classes set out in Schedule 4 to the Act, or a cannabis accessory that contains such cannabis, after it has been packaged and labelled for sale to a consumer at the retail level. It does not include:
  • cannabis that is intended for an animal
  • health products containing cannabis or for use with cannabis
  • a cannabis accessory that contains cannabis that is intended for an animal
• An adverse reaction is a noxious and unintended response to cannabis or a cannabis accessory that contains cannabis
• A serious adverse reaction is an adverse reaction that requires inpatient hospitalization or a prolongation of existing hospitalization, causes congenital malformation, results in persistent or significant disability or incapacity, is life-threatening or results in death

Licence holders who sell or distribute a cannabis product must provide Health Canada with a detailed report must within 15 days of becoming aware of a serious adverse reaction to the cannabis product. This report must contain all information in their possession associated with the use of the cannabis product by the individual who experienced the reaction.

The following groups may also submit adverse reaction reports on a voluntary basis to Health Canada:

• patients
• consumers
• health care practitioners
• medical cannabis clinics
• other reporters such as provincial and territorial authorized retailers

Reports may also be received from market authorization holders of licensed health products that submit adverse reaction reports for other suspect health products (such as prescription or non-prescription drugs, or natural health products) in which cannabis is also identified as a co-suspect product.

Adverse reaction reports with cannabis may involve cannabis that is:

• from an illegal source
• a legal cannabis product
• cultivatedFootnote 3 or producedFootnote 4 in the home for personal use
• undefined (cannabis as a substance not otherwise specified)

For the purposes of this report, case reports involving a legal cannabis product (that is, identifiable by legal product brand name or legal licence holder) are classified according to the intended use of the cannabis products as follows:

• Cannabis use for non-medical purposes: If there is no reported medical or therapeutic indication or reason for use provided in the adverse reaction report, if the report contains minimal details, or the intended use of cannabis is for non-medical purposes, the case is classified as "non-medical use of cannabis".
• Cannabis use for medical purposes: This includes cases described as involving the cannabis being used pursuant to a medical authorization document provided by a health care practitioner, or cases that report the use of the cannabis for a medical or therapeutic purpose, without mention of a medical authorization document. This definition aligns with the definition of medical use of cannabis within the Canadian Cannabis Survey. This is broader in scope than the definition of cannabis use for medical purposes under the Cannabis Regulations which only includes cannabis obtained with a medical authorization document from a health care practitioner.

Adverse reaction reports are collected and housed in the Canada Vigilance database. Most adverse reaction case reports submitted to Health Canada with cannabis are reported spontaneously by consumers, patients, health care practitioners or by licence holders (referred to as market authorization holders [MAH] in the Canada Vigilance database). However, reports may also originate from research studies, including:

• published case studies
• observational studies (non-interventional, real-world)
• interventional human studies involving cannabis that fall outside of the definition of a clinical trial (for example, non-therapeutic research on cannabis studies)
• other organized data collection systems (for example, patient registries)

While reports originating from clinical trials may be included in the broader Canada Vigilance dataset, these reports are excluded from this data report as they fall under the purview of the Clinical Trials Framework under the Food and Drugs Act and Regulations.

Health Canada conducts near-time monitoring, detection, and assessment of cases of adverse reactions involving cannabis products as part of the Vigilance Framework for Cannabis. Health Canada also monitors cases involving cannabis as a substance for broader issues of public health importance such as:

• vaping-associated lung illness
• cases involving pediatric populations
• other potential emerging safety issues

The purpose of this report is to provide a brief summary of adverse reaction reports involving cannabis, as well as a descriptive analysis of adverse reaction data associated with legal cannabis products, submitted to Health Canada between January 1, 2023, and December 31, 2023.

In addition to the descriptive analysis of cases from 2023, comparisons to the previous reporting period (January 1, 2022, to December 31, 2022) have been made, where appropriate. These comparisons are largely descriptive, and differences have not been tested for statistical significance in most cases due to the limited nature of the data. Therefore, caution should be taken when interpreting changes in results over the 2 reporting periods.

Data for other reporting periods, including trends across periods, are also publicly available:

• Key findings: Cannabis-related side effects
• Data on cannabis adverse reactions

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