Acute Stress Reaction

NICE guideline [NG116] Post-traumatic stress disorder. Published: Dec 2018.

Article Last Updated:28/07/2026

Acute Stress Reaction

Acute stress reaction is also known as acute stress disorder:

The UKMLA map and ICD-11 use the term acute stress reaction
DSM-5 criteria use the term acute stress disorder

General Psychiatry Article Disclaimer

DSM-5 criteria or ICD-11 diagnostic requirements are used to structure the Clinical Features and Diagnosis section. The classification system used is selected according to its clarity and suitability for non-specialist learning.
The criteria are summarised and simplified rather than reproduced in full, while preserving their original diagnostic meaning.
Where appropriate, a student-friendly pattern-recognition summary is provided to highlight the most clinically and exam-relevant features.

Exam tip (re-psychiatry questions)

Do not attempt to memorise every DSM-5 or ICD-11 criterion word-for-word. However, it is important to read through the criteria and become familiar with the key symptom clusters, duration thresholds, exclusions, and distinguishing features highlighted in this article.
Exam questions may not provide every feature required to meet the full diagnostic criteria. Familiarity with the criteria can help one recognise the most likely diagnosis, exclude important alternatives, and narrow the differential diagnosis.

Causes

Acute stress disorder develops after exposure to actual or threatened death, serious injury, or sexual violence ^[Ref]

Exposure may occur through: ^[Ref]

Directly experiencing the traumatic event
Witnessing the event occurring to another person
Learning that the event occurred to a close family member or close friend
Repeated or extreme occupational exposure to distressing details of traumatic events (e.g. emergency responders)

Acute stress reaction is a transient, expected response to trauma rather than a mental disorder.

Clinical Features and Diagnosis

High-yield pattern recognition for acute stress reaction:

Onset of stress symptoms after a traumatic event
Which lasts for 3 days to 1 month
That is causing significant distress or functional impairment
Not better explained by a different underlying cause

According to the DSM-5 criteria, acute stress disorder can be clinically diagnosed when ALL the following criteria are met: ^[Ref]

Diagnostic criteria	Criteria description
Exposure to a traumatic event	Exposure to actual or threatened death, serious injury, or sexual violence (see above for examples)
Presence of trauma stress symptoms	Patient must develop at least 9 of the following symptoms from the 5 categories (that begin or worsen after the traumatic event) Intrusion Recurrent, involuntary, and distressing memories of the trauma Recurrent distressing dreams related to the trauma Dissociative reactions or flashbacks, during which the person feels or behaves as though the trauma is recurring Intense or prolonged psychological distress or marked physiological reactions when exposed to reminders of the trauma Negative mood Persistent inability to experience positive emotions, such as happiness, satisfaction, or loving feelings Dissociation Altered perception of oneself or the surroundings, such as feeling detached, being in a daze, or experiencing time as slowed Inability to remember an important aspect of the trauma due to dissociative amnesia, rather than head injury, alcohol, or drug Avoidance Attempts to avoid distressing memories, thoughts, or feelings related to the trauma Attempts to avoid external reminders of the trauma, such as people, places, conversations, activities, objects, or situations Arousal Sleep disturbance Irritability or angry outbursts, which may include verbal or physical aggression Hypervigilance Difficulty concentrating Exaggerated startle response
Duration	Symptoms typically begin immediately after the trauma and must persist for 3 days to 1 month after the traumatic event Note that symptoms lasting <3 days do NOT meet the criteria, and symptoms lasting >1 month should prompt assessment for PTSD
Presence of functional impairment	The symptoms must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning
Exclusion of other causes	The disturbance must not be attributable to ANY of the following: Substance use (e.g. alcohol, medications) Medical condition (e.g. TBI) Brief psychotic disorder