Delirium

Evidence-based mental health content, reviewed by psychologists and psychiatrists

Delirium

Medically reviewed · Ratel Health editorial team · Sunday, 16 August 2026

An acute disturbance in attention and awareness that develops over a short period and tends to fluctuate in severity, usually caused by an underlying medical condition.

Overview

Delirium is an acute disturbance in attention, awareness, and cognition that develops over hours to days and tends to fluctuate throughout the day. It is usually caused by an underlying medical condition, substance effect, or withdrawal.

Signs and Symptoms

Symptoms can include difficulty focusing or sustaining attention, disorientation, memory problems, perceptual disturbances, and fluctuating alertness ranging from drowsy to agitated. Experiencing one or more of these symptoms does not necessarily mean that a person has this condition. Diagnosis requires an appropriate clinical evaluation.

Causes and Risk Factors

Delirium is caused by an underlying medical condition such as infection, medication effects, surgery, substance intoxication or withdrawal, or organ dysfunction, often in people who are medically vulnerable, such as older adults.

Diagnosis

A diagnosis should be made by a qualified healthcare professional following a comprehensive clinical assessment. Clinicians may use established diagnostic frameworks such as DSM-5-TR and/or ICD-11 as part of a comprehensive assessment.

Treatment

Treatment depends on the individual’s symptoms, clinical history, severity, age, co-occurring conditions, and other relevant factors.

Psychotherapy

Non-pharmacological approaches such as reorientation, a calm and consistent environment, and addressing sensory impairments are important supportive measures.

Medication

Treatment focuses on identifying and addressing the underlying medical cause; medication for agitation may occasionally be used cautiously under medical supervision. Medication decisions should be made with a qualified prescribing healthcare professional. Do not start, stop, or change a prescribed medication based solely on information on this page.

Living With Delirium

Family involvement, minimizing environmental disruption, and close medical follow-up support recovery.

When to Seek Professional Help

Professional evaluation may be appropriate if symptoms persist, worsen, cause significant distress, or interfere with work, school, or relationships. Delirium is a medical concern that typically requires prompt evaluation.

Emergency Situations

If a person may be in immediate danger, is experiencing a medical or psychiatric emergency, or may harm themselves or another person, seek immediate assistance through appropriate local emergency services.

Outlook

Delirium often resolves once the underlying cause is treated, though recovery can take time, particularly in older adults, and it is associated with increased medical risk.

Related Conditions

Medical Information Disclaimer

Ratel Health provides general educational information and does not provide medical diagnosis, treatment, or individualized medical advice. Information on this page is not a substitute for evaluation or care from a qualified healthcare professional. Do not use this information to diagnose yourself or another person, or to start, stop, or change treatment or medication without consulting an appropriately qualified healthcare professional.

References

  • American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR).
  • National Institutes of Health.
  • Centers for Disease Control and Prevention.
  • World Health Organization. International Classification of Diseases, 11th Revision.