People from all walks of life have taken drugs throughout human history, for many reasons, with the most commonly used drugs being alcohol and cannabis. Most substance use does not harm the individual or anyone else. However, in a small percentage of cases, people can experience negative consequences from their substance use, or become physically or psychologically dependent.

There is a broad range of substance use – from abstinence to dependence. An individual’s substance use may change throughout their life, for a variety of reasons.

Regardless of where someone finds themselves on the continuum of drug use, overdose can be a risk depending on the amount consumed and if a combination of substances is consumed. This can happen intentionally or unintentionally, especially given the unpredictable nature of the current unregulated drug supply.

Drug tolerance refers to when a person’s body gets used to a specific dose or quantity of a particular drug, and therefore they require more of the drug to experience the desired or intended effect. Tolerance increases over time with continued drug use and decreases quickly.

Reduced tolerance to opioids creates a serious risk for overdose. Even a few days without using opioids can lead to a significant drop in tolerance. This can happen when someone participates in drug treatment, takes a voluntary break, is incarcerated, becomes ill, or their usual drug supply is otherwise inaccessible. A drop in opioid tolerance means that the body can process only a smaller amount of the specific opioid than what someone previously consumed, without overdosing.

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

  • Depressant drugs, also called “down or downers,” slow down central nervous system activity, reducing arousal and stimulation. Opioids, benzodiazepines and alcohol are all types of depressant drugs. Naloxone does NOT work to reverse the effects of ALL depressants; it only reverses the effect of opioids.
    • Examples of opioids include heroin, fentanyl, fentanyl analogues, hydromorphone (or DilaudidTM), oxycodone, morphine, methadone and SuboxoneTM. Prescribed opioids are used to treat pain, cough, diarrhea, opioid use disorder, and to replace unregulated opioids to provide a safer alternative. Some people use opioids non-medically to feel very relaxed, “high,” less inhibited, or to escape discomfort.
    • Benzodiazepines, sometime referred to as “benzos,” are widely prescribed to treat conditions like insomnia, anxiety, alcohol withdrawal, and seizure disorders. Benzodiazepines can cause feelings of tranquility and physical relaxation. Some examples of pharmaceutical benzodiazepines include lorazepam (or AtivanTM), diazepam (or ValiumTM), and alprazolam (or XanaxTM). Potent unregulated benzodiazepines and benzodiazepine-like substances such as flualprazolam and etizolam have been found in unregulated drug supply samples in Toronto.
  • Stimulants are substances that speed up a person’s central nervous system activity, and are used to increase alertness, wakefulness, energy and confidence. They can also be prescribed to treat attention deficit and hyperactivity disorders. Common stimulants include cocaine, crack cocaine, amphetamines (which are also known as “speed” or “uppers” and are found in crystal meth as well as pharmaceuticals like AdderallTM). Methylphenidate (or RitalinTM). Caffeine and nicotine are also stimulants. Large doses of stimulants can cause over-stimulation, anxiety, panic, seizures, headaches, stomach cramps, aggression, and paranoia. Naloxone does not counteract the effects of stimulants.
  • Hallucinogenic substances can cause visual, auditory and psychological changes, alter level of consciousness and cause fluctuations in heart rate, respiratory rate and body temperature. They are used for recreational, experimental and spiritual experiences. There is also emerging evidence that some psychedelics may be therapeutically beneficial when used under medical supervision to treat some depression, anxiety and post-traumatic stress disorder, although these drugs remain unregulated in Canada. LSD, psilocybin (or magic mushrooms), MDMA, mescaline, and DMT are all Ketamine and PCP (or angel dust) are examples of dissociative hallucinogens. Naloxone does not reverse the negative effects caused by hallucinogens.

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 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:

  • Programs that distribute sterile syringes, pipes for smoking drugs, and other harm reduction supplies. Learn more about where to access these programs and services.
  • The distribution of naloxone to reverse opioid overdose. Naloxone is freely available through community organizations and many pharmacies. Find out where to get a naloxone kit.
  • Supervised consumption services that provide people with a safe place to use drugs where medical support is available if an overdose occurs. People also have the opportunity to be connected to other supports. Find locations and hours of supervised consumption services..
  • Safer supply programs, which provide prescription opioids to reduce the risk of overdose from the unregulated supply and help create stability in the lives of people who use drugs.