Substances & Substance Use

Substance use patterns vary greatly and cover a wide spectrum of use.  Many people use substances and not all substance use is a problem.

Health Canada notes that “people use substances, such as controlled and illegal drugs, cannabis, tobacco/nicotine, and alcohol, for different reasons, including medical purposes; religious or ceremonial purposes; personal enjoyment; or to cope with stress, trauma or pain.”

Substance use disorder is a treatable medical condition that involves compulsive and continuous use despite negative impacts to a person, their family, friends & others.

Continuum of Use & Tolerance

Substance use exists on a spectrum, from not using at all to regular use or dependence, and can change over time. Overdose can happen at any stage, depending on how much is used and if substances are mixed—especially with today’s unpredictable drug supply.

The body builds tolerance to drugs over time, meaning more is needed to feel the same effects. However, tolerance can drop quickly after even a short break, increasing the risk of overdose. This is especially dangerous with opioids—if someone stops using for a few days due to treatment, incarceration, illness, or lack of access, a dose they used before could now be too much and lead to overdose.

Substances

There are three main classes of drugs: depressants, stimulants and hallucinogens (or psychedelics).

  • Depressants (e.g., opioids, benzodiazepines, alcohol) slow the nervous system. Opioids include fentanyl, heroin, oxycodone, and morphine. Naloxone only reverses opioid overdoses.
  • Stimulants (e.g., cocaine, amphetamines, nicotine, caffeine) increase alertness and energy. Large doses can cause anxiety, paranoia, and seizures. Naloxone does not reverse stimulant effects.
  • Hallucinogens (e.g., LSD, psilocybin, MDMA, ketamine) alter perception and consciousness. Some psychedelics show potential for medical use in treating mental health conditions but remain unregulated in Canada. Naloxone does not counteract hallucinogens.

What Is An Opioid Overdose?

An overdose occurs when a person consumes a toxic amount of a drug, or combination of drugs.

As a result, the central nervous system is no longer able to control basic life functions such as breathing, heart rate, body temperature, or consciousness.

When someone stops breathing the brain has approximately three minutes worth of oxygen in reserve. Permanent brain damage can occur within 10 minutes of oxygen deprivation.

Overdose is a life-threatening medical emergency. If you recognize that someone is overdosing, it is vital to act quickly.

Learn how to prevent and respond to an overdose.

Harm Reduction

Harm reduction programs and services reduce drug-related harm for people who use drugs, including overdose, and infectious disease transmission.

Harm reduction aims to meet people who use drugs “where they are.”

Examples of harm reduction programs and services are: