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What is a psychoactive substance?

According to the World Health Organization (WHO), “Psychoactive substances are substances that, when taken in or administered into one’s system, affect mental processes, e.g., cognition or affect.” These substances may cause feelings of relaxation, euphoria and the loss of inhibitions, as well as more intense effects such as hallucinations.

The effects of alcohol

Alcohol is a central nervous system depressant, or simply central depressant. This means that it slows down certain brain and body functions, including breathing and heart rate.

The intensity of the effects caused by alcohol depends on many factors, such as:

  • An individual’s sex, age and weight
  • A drink’s alcohol content (percentage of alcohol by volume)
  • The amount absorbed
  • The rate at which alcohol is absorbed
  • A person’s mood
  • Whether or not food is ingested
  • The taking of medications

After one drink, an individual will generally feel more relaxed, more self-confident, euphoric and emotional. Increasing the dose may result in other effects:

  • Visual impairment
  • Loss of balance
  • Nausea and vomiting
  • Aggression or depression
  • Loss of reflexes
  • Difficulty speaking

Consuming excess alcohol can also have indirect consequences. By lowering the inhibitions of the drinker and boosting their confidence, alcohol can lead to violent behaviour, risky behaviour (impaired driving, unprotected sex, etc.) or even suicidal behaviour in certain people, such as individuals with depressive disorders or personality disorders.

Psychological addiction and physical addiction

Drinking alcohol can cause both psychological and physical addiction. Psychological addiction stems from alcohol’s psychoactive effects. For people with an addiction, consuming alcohol can become the main or even the only means to:

  • Feel relaxed
  • Feel motivated
  • Feel confident
  • Fall asleep more easily

Physical addiction happens when the body becomes addicted to alcohol. When people with an addiction stop using, they may experience symptoms such as:

  • Tremors
  • Nausea
  • Rapid heartbeat
  • High blood pressure
  • Insomnia
  • Excessive sweating
  • Anxiety or depression
  • Irritability
  • Confusion

These symptoms are the result of withdrawal, i.e., deprivation of the substance to which the person has become addicted. Withdrawal symptoms may be felt within six to 48 hours after ceasing alcohol consumption. Although they can disappear on their own, in some cases they may lead to complications.

Treatment of withdrawal

Withdrawal symptoms can be very severe in persons who have been drinking excessively and who suddenly decrease or stop drinking. While the effects of withdrawal usually disappear within two to five days, complications may occur, resulting in fever, hallucinations or seizures. In the most severe cases, delirium tremens can put a person into a coma and result in death.

Alcohol withdrawal may require personalized medical support. When withdrawal symptoms are severe, they can be treated with certain medications such as benzodiazepines, which have a tranquillizing effect and can prevent seizures. These can be enhanced with beta blockers, anticonvulsants or neuroleptics, which help prevent the progression to delirium tremens.

Note: these treatments can be risky. Only health professionals can decide whether to use them to treat alcohol withdrawal symptoms.

Screening: self-assessment of alcohol consumption

A number of questionnaires are available to self-assess one’s alcohol consumption and to identify a possible addiction. These include:

  • ADS (Alcohol Dependence Scale – link to French questionnaire)
  • AUDIT (Alcohol Use Disorders Identification Test)
  • CAGE (Cut-down, Annoyed, Guilty, Eye-opener)
  • DEP-ADO (link to french questionnaire)

Caution: these self-assessments have no clinical or scientific value and do not replace the diagnosis of a health professional.

We can help you

If you are concerned about your drinking or that of a loved one, you don’t have to face it alone: call us at 1-800-265-2626 or use the chat feature at the bottom of our site, on the right. We can offer you personalized support and information and refer you to resources tailored to your situation. Our services are available 24 hours a day, 7 days a week. They are also anonymous and free of charge.


Sources : Diagnostic and Statistical Manual of Mental Disorders (DSM-5) / World Health Organization (WHO) / Addiction Prevention Centre (APC) / Cairn.info / Government of Canada / Société française de médecine d’urgence