Substance Intoxication Delirium

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Substance Intoxication Delirium is the diagnostic name for alcohol or drug-induced delirium, which occurs during intoxication from a psychoactive substance.

Unlike the transient disturbances in attention that are normal and that everyone experiences from time to time when tired, or even the temporary loss of focus and attention that affects people the who are under the influence of alcohol or drugs, substance intoxication delirium is considerably worse and lasts for much longer. For some people, it involves a complete inability to attend to the external environment.

Symptoms of Delirium

Delirium is a change in someone's state of consciousness, which significantly disrupts their attention, awareness, and ability to process information about the world around them. They become less able to direct and focus their attention, keep their attention focused on something over time, or shift their attention from one thing to another.

Their attention can wander so dramatically that questions need to be repeated for the person to be able to focus long enough to answer, or they may continue to focus on giving the answer to a previous question when a new question has been asked. They can easily be distracted by things that have nothing to do with what is being asked.

In severe cases of delirium, they may be so disoriented that they might not know where they are or even who they are.

Impact on Memory

As well as the change in attention and focus, there is at least one other area of mental functioning that is affected. The person might not be able to remember properly, and in particular, they may lose their memory for events that have just recently happened. It could be orientation, and they may have particular trouble knowing where they are and the time and date.

Other mental functions that may be affected are learning, language, or problems with perception, which can even take the form of hallucinations. When physicians give a diagnosis of substance intoxication delirium, they check to make sure that the delirium is not part of another condition that affected the person before becoming intoxicated from alcohol or drugs.

Physical Causes

A condition like this could be well-established in the person's medical record, or it might be a condition that has been emerging for a while. As there are different physical causes of delirium, and if the symptoms were there before the substance withdrawal, it isn't the medication intoxication type of delirium. Although a person can eventually fall into a coma, at that point, delirium would not be diagnosed.


In some cases, delirium can occur during intoxication, soon after the substance has been consumed and has taken effect. Even after the drug has worn off, sometimes delirium can continue, and there is even another diagnosis called substance withdrawal delirium, which means that the episode of delirium occurs after the person has discontinued using the substance, and is experiencing withdrawal.

Whether the delirium starts during intoxication or withdrawal, it will usually subside within hours or days of ceasing to take the drug, although in withdrawal, delirium can sometimes last for weeks.

Delirium usually develops over a fairly short period of time, ranging from a few hours to a few days. The severity of the disturbance in orientation to the environment and thought processes changes a fair bit during the course of delirium and is usually worse towards night-time when there is less going on around the person to help keep them oriented.


A wide variety of psychoactive substances can cause substance intoxication delirium, including:

  • Alcohol intoxication delirium
  • Amphetamine intoxication delirium
  • Anxiolytic intoxication delirium
  • Cannabis intoxication delirium
  • Cocaine intoxication delirium
  • Hypnotic intoxication delirium
  • Inhalant intoxication delirium
  • Opioid intoxication delirium
  • Other hallucinogen intoxication delirium
  • Other stimulant intoxication delirium
  • Other substance intoxication delirium
  • Phencyclidine intoxication delirium
  • Sedative intoxication delirium
  • Unknown substance intoxication delirium

When people develop symptoms of delirium after consuming alcohol or another drug, they require immediate medical attention. If someone seems to be in this state, call 911 immediately, and let the paramedics know what they have taken.

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  • American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders, fifth edition, DSM-5. American Psychiatric Association, 2013.
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