Abuse of substances such as alcohol, marijuana, cocaine, prescription medications, and others can cause health issues and serious problems with family, friends, coworkers, job, money, and the law. Yet despite these problems, use of the substance continues.
Substance use and addiction
What is substance use and addiction?
Many people use substances such as drugs or alcohol to relax, have fun, experiment, or cope with stressors; however, for some people, the use of substances or engaging in certain behaviours can become problematic and may lead to dependence.
Addiction is a complex process where problematic patterns of substance use or behaviours can interfere with a person’s life. Addiction can be broadly defined as a condition that leads to a compulsive engagement with a stimuli, despite negative consequences.i This can lead to physical and/or psychological dependence. Addictions can be either substance-related (such as the problematic use of alcohol or cocaine) or process-related, also known as behavioural addictions (such as gambling or internet addiction). Both can disrupt an individual’s ability to maintain a healthy life, but many support and treatment options are available.
A simple way of understanding and describing addiction is to use the 4C’s approach:
- Craving
- Loss of control of amount or frequency of use
- Compulsion to use
- Continued substance use despite consequences
How common is substance use and addiction?
Substance use is quite common internationally, and statistics vary depending on the substance. It is estimated that nearly 5% of the world’s population have used an illicit substance, 240 million people around the world use alcohol problematically, and approximately 15 million people use injection drugs.
In Canada, it is estimated that approximately 21% of the population (about 6 million people) will meet the criteria for addiction in their lifetime. Alcohol was the most common substance for which people met the criteria for addiction at 18%. Cannabis, also known as Marijuana, has one of the highest rates of cannabis use in the world, with more than 40 percent of Canadians having used cannabis in their lifetime and about 10 percent having used it in the past year.
While some people may be able to consume substances without resulting in significant harms, some people may experience ongoing substance-related problems. In Ontario, it is estimated that approximately 10% of the population uses substances problematically. Recently, Ontario has seen a growing trend of harms related to opioid use. Opioids are a class of psychoactive drugs that are often used for pain management. These can include fentanyl, morphine, heroin, and oxycodone. While opioids are effective for pain relief, and many individuals can use them for short periods of time without concern, this class of drugs has led to harms across the province in recent years, including deaths due to overdose. In 2016, there were 865 deaths due to this substance, equal to an opioid related overdose death occurring in Ontario every 10 hours
Source: © 2026 CMHA Ontario, Canadian Mental Health Association
