About problematic substance use (substance abuse)

Substance abuse is the harmful or hazardous use of prescription and illegal drugs for non-medical reasons. Although the use of these drugs can pose a number of physical harms, these drugs mainly affect the functioning of the nervous system and the way a person thinks, feels or acts. Abusing drugs can also lead to physical dependence and addiction.

Learn the signs and symptoms of substance abuse and how to prevent it.

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Addiction and dependence

When someone regularly uses alcohol or drugs despite negative consequences, they may be addicted. They may not be aware that their behaviour is out of control and that they are causing problems for themselves and others.

Addiction involves psychological dependence and may or may not also include physical dependence.

Psychological dependence is also known as dependence of the mind. When a person is psychologically dependent, it becomes extremely hard for them to stop using or even thinking about the drug. Strong cravings for the drug may be triggered by internal or external cues. This behaviour is reinforced by consuming the drug in response to a trigger.

Physical dependence is observed when the user needs the drug to function normally and has negative symptoms of withdrawal when the user stops or decreases use of the drug.

Effects of long-term substance abuse

Long-term substance abuse causes changes to the brain and body that can become permanent. This may affect:

  • judgment
  • decision making
  • learning
  • memory
  • behaviour

Short-term effects of taking a drug

How people feel after taking a drug can vary from person to person, and even from one use to another. The effects of taking a drug depend on factors such as:

  • age, sex and weight;
  • any medical or mental health conditions;
  • the amount of the drug consumed; and
  • the combined use with other drugs like:
    • alcohol
    • over-the-counter medication
    • prescription drugs
    • other illegal drugs

Preventing substance abuse

Educating people about the dangers of drug use is the main way to prevent substance abuse. Families, schools, communities, and the media can all help with this education. Early intervention programs are also more effective when all of these groups are involved.

As a parent, you can talk to your teenager about drugs and watch for signs and symptoms of drug abuse.

Did you know?

Psychoactive pharmaceuticals are the third most commonly-abused substances, after alcohol and marijuana, among Canadian youth. Learn more about prescription drug abuse.


When the user becomes accustomed to a particular dose of a drug and needs higher dosages in order to obtain the same effects, he or she is likely to have developed tolerance to the drug. Users with increased tolerance are at higher risk of overdose.


An overdose occurs when the person takes more of a drug than their body can handle. An overdose may result in serious, harmful symptoms or death.

Symptoms of overdose:

  • pinpoint or dilated pupils
  • changes in core body temperature (hypothermia or hyperthermia)
  • changes in blood pressure, heart rate and breathing rate
  • bluish skin
  • loss of consciousness which may lead to coma
  • seizures


Withdrawal symptoms occur when a person stops or reduces taking a drug after using regularly for a long time or after using high doses. Withdrawal symptoms can vary and can depend on the kind of drug used, but some withdrawal symptoms can be the opposite of the acute effects seen with the drug.

For example, the loss of appetite seen with stimulants such as cocaine or methamphetamine can be followed by ravenous hunger. The decreased sensation of fatigue associated with stimulant use can be followed by feelings of extreme fatigue and sleepiness. Withdrawal can occur with illegal drugs or prescription drugs.

Drug paraphernalia

Drug paraphernalia refers to any equipment that is used to produce, conceal and consume illicit drugs, such as:

  • bongs
  • roach clips
  • spoons, straws
  • needles
  • various types of pipes

Under section 462.2 of the Criminal Code, it is a criminal offence to import, export, manufacture, promote or sell instruments for illicit drug use.

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