What Is Substance Intoxication Delirium?

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What Is Substance Intoxication Delirium?

Substance intoxication delirium is the diagnostic name for alcohol or drug-induced delirium. The condition is caused by intoxication from a psychoactive substance.

Disturbances in focus and attention are normal when people are under the influence of alcohol or drugs, and even when they are overtired. However, loss of focus and attention is usually temporary.

Substance intoxication delirium is a more serious state that may last longer than the transient symptoms most people experience when they are intoxicated. In addition, a person who is experiencing substance intoxication delirium will have additional disturbances in their cognition and may become completely unable to attend to the external environment.

Here's what you need to know about the symptoms of substance intoxication delirium and what to do if you or someone you know is experiencing it.

Symptoms of Delirium

Delirium is a change in someone's state of consciousness that significantly disrupts their attention, awareness, and ability to process information about the world around them.

Attention and Focus

Someone who is experiencing delirium becomes less able to direct and focus their attention, keep their attention focused over time, or shift their attention from one thing to another.

If you are talking to someone with delirium, you might notice that you need to repeat your questions. The person might continue to focus on giving an answer to the first question even when you have asked another. When a person is delirious, it is easy for them to become distracted by something that has nothing to do with what they have been asked.

In severe cases of delirium, a person can become so disoriented that they might not know where they are—or even who they are.


In addition to the loss of attention and focus, a person may develop deficits in their memory. A person experiencing substance intoxication delirium might not be able to remember things properly, and in particular, they may lose their memory for events that have recently happened.

People experiencing delirium might also lose their sense of orientation. They may not know where they are, the time, or the date.

A person's learning, language, and perception (which can include hallucinations) can also be affected.

Causes of Substance Intoxication Delirium

Before a healthcare provider makes a diagnosis of substance intoxication delirium, they will check to make sure that the delirium is not from a condition that affected the person before becoming intoxicated from alcohol or drugs.

There are different causes of delirium. A condition might be present in a person's medical record, or it could be undiagnosed.

Substances That Can Cause Delirium

There are many psychoactive substances that can cause substance intoxication delirium. Some of the substances that are known to cause delirium are:

  • Alcohol
  • Amphetamines
  • Anxiolytics
  • Cannabis
  • Cocaine
  • Hypnotics
  • Inhalants
  • Opioids
  • Other hallucinogens
  • Other stimulants
  • Phencyclidines
  • Sedatives
  • Unknown substances

How Long Does Substance Intoxication Delirium Last?

Delirium usually develops over a short period—from a few hours to a few days after the substance is taken. Delirium's severity can change over time, but it's often worse at night when there is less happening in a person's environment that can help keep them oriented.

Delirium usually occurs soon after a substance has been consumed and starts to take effect. In some cases, delirium continues even after the drug has worn off. Delirium can also occur in the context of substance withdrawal.

Substance withdrawal delirium occurs after a person has discontinued using a substance (when they are in withdrawal).

Whether delirium starts during intoxication or withdrawal, it usually subsides within hours or days after a person stops using the substance. However, delirium can sometimes last for longer during withdrawal.

Substance Intoxication Delirium Treatment

Someone who develops delirium after using or while withdrawing from alcohol or any other substance needs immediate medical attention. If you are with someone who has taken a substance and has symptoms of delirium, call 911 and tell the paramedics what the person has taken.

People with a substance use disorder and those who are in severe withdrawal need close medical monitoring, either in the hospital or a treatment center.

A Word From Verywell

Delirium from substance use can be serious. If someone is using alcohol or any other substance and they develop symptoms of delirium—such as being unable to answer questions, being disoriented, or having trouble remembering things—they need immediate medical care.

People who are using substances or withdrawing from substances often need to be closely monitored by a healthcare professional to ensure their safety. Medical care is also important, because in some cases delirium is caused by a condition that is not related to substance use. Only a medical professional can make a diagnosis and recommend the appropriate treatment.

Substance Use/Addiction:

If you or a loved one are struggling with substance use or addiction, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area. 

For more mental health resources, see our National Helpline Database.

6 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Psychological Association (APA). APA Dictionary of Psychology: Substance intoxication delirium.

  2. American Psychiatric Association (APA). Diagnostic and Statistical Manual of Mental Disorders (DSM-5®). American Psychiatric Pub; 2013. doi:10.1176/appi.books.9780890425596

  3. Center for Substance Abuse Treatment. Substance-Induced Disorders. In: Substance Abuse Treatment for Persons With Co-Occurring Disorders. Rockville (MD): Substance Abuse and Mental Health Services Administration (US); 2005. 

  4. Stern TA. Massachusetts General Hospital Comprehensive Clinical Psychiatry. Elsevier Health Sciences; 2015:173-183.

  5. Anderson, M. The Neuropsychology of Cortical Dementias. Springer Publishing Company; 2014:347-361.

  6. Juhnke GA. Substance Abuse Assessment and Diagnosis: A Comprehensive Guide for Counselors and Helping Professionals. New York; 2002:49-52.

By Elizabeth Hartney, BSc, MSc, MA, PhD
Elizabeth Hartney, BSc, MSc, MA, PhD is a psychologist, professor, and Director of the Centre for Health Leadership and Research at Royal Roads University, Canada.