Cannabis is one of the most commonly used substances in Canada. In 2024, about one in four people (26%) people living in Canada said they had used cannabis within the past year, and 6% said they used it daily or almost daily (Health Canada, 2024a).

There is strong evidence that using cannabis often can lead to several health problems. These effects include mental health disorders, changes in brain function, problematic cannabis use and cannabis use disorder (CUD). The risks appear to be much higher for people who use products that contain large amounts of delta-9-tetrahydrocannabinol (Δ-9- THC), the main psychoactive component in cannabis (Colizzi et al., 2020; Freeman & Winstock, 2015; Murray & Hall, 2020).

Recent reports from the National Academies of Sciences, Engineering and Medicine (2024) and from Health Canada’s review of the Cannabis Act (Health Canada, 2024b) highlight growing public health concerns about high-THC products. These products are becoming more available and more popular, raising the potential for increased cannabis-related harms.

A lesser-known health concern linked to long-term cannabis use, and possibly to high-THC products, is cannabis hyperemesis syndrome (CHS). CHS is marked by cycles of severe nausea, vomiting and stomach pain. As both the use and access to cannabis and high-THC products continue to rise, understanding and addressing CHS is increasingly important for public health and cannabis policy in Canada.