Acute Stress Disorder (ASD)
What happens when reactions to trauma are severe in the first month, how clinicians define it, and what research says helps.
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Acute stress disorder (ASD) is a mental health diagnosis in the DSM-5-TR for severe trauma-related symptoms, such as intrusive memories, dissociation, avoidance and hyperarousal, that last from three days to one month after a traumatic event. It describes a reaction that is more intense and disabling than the ordinary distress most people feel after trauma, during the period before post-traumatic stress disorder (PTSD) can be diagnosed.
ASD is not simply "early PTSD," and it does not always lead to PTSD. In many studies roughly half of people diagnosed with ASD went on to meet criteria for PTSD, but many recovered, and many people who later developed PTSD never had ASD in the first month. The diagnosis is mainly useful as a way of recognizing people whose early reactions are severe enough that professional assessment and support may help.
Understanding Acute Stress Disorder
What ASD is
ASD is a cluster of trauma-related symptoms, grouped into intrusion, negative mood, dissociation, avoidance and arousal, that begins or worsens after a traumatic event and persists for between three days and one month. If symptoms are present in the first few days but then fade, no diagnosis is made. If they persist beyond a month, clinicians consider PTSD, which has its own criteria.
The diagnosis was introduced in DSM-IV in 1994. At the time, it placed heavy emphasis on dissociative symptoms, such as feeling numb or detached, because researchers believed dissociation during or soon after trauma predicted later PTSD. Later research found that dissociation was a less reliable predictor than expected, so DSM-5 (2013) changed the criteria to require any nine of fourteen symptoms, without requiring dissociation specifically.
Why the three-day lower boundary?
The first hours and days after a traumatic event are often marked by intense reactions: shock, fear, intrusive images, disturbed sleep, tearfulness or numbness. These responses are extremely common and are generally understood as a normal reaction to an abnormal event. The three-day minimum helps avoid labeling an expected short-lived response as a disorder.
Why the one-month upper boundary?
Studies following people after trauma, such as accidents or disasters, show that many people's symptoms decrease substantially over the first weeks and months. The one-month limit marks the point at which DSM allows a diagnosis of PTSD, which is designed for longer-lasting difficulties.
How ICD-11 differs
The World Health Organization's ICD-11 takes a different approach. It does not include acute stress disorder as a mental disorder. Instead, "acute stress reaction" is listed in a chapter for factors influencing health, described as a normal response to an exceptionally stressful event that typically begins to subside within a few days. This difference reflects ongoing debate about whether a one-month diagnosis adds value or risks treating normal distress as illness.
DSM-5-TR Diagnostic Criteria
The following is an educational summary of how the DSM-5-TR describes ASD. Diagnosis requires assessment by a qualified clinician, who also considers context, other conditions and the person's own account.
Criterion A: trauma exposure
Exposure to actual or threatened death, serious injury or sexual violence in one or more of these ways: directly experiencing it; witnessing it happen to others in person; learning that it happened to a close family member or friend (where the death or threat was violent or accidental); or repeated or extreme exposure to distressing details, as can happen to first responders. Exposure through media does not count unless it is work-related.
Criterion B: nine or more symptoms
The DSM-5-TR lists fourteen possible symptoms in five categories, of which at least nine must be present, beginning or worsening after the event:
| Category | Symptoms described |
|---|---|
| Intrusion | Recurrent involuntary distressing memories; distressing dreams related to the event; dissociative reactions such as flashbacks; intense or prolonged distress or physical reactions to reminders |
| Negative mood | Persistent inability to experience positive emotions such as happiness or love |
| Dissociation | An altered sense of reality of oneself or one's surroundings; inability to remember an important aspect of the event |
| Avoidance | Efforts to avoid distressing memories, thoughts or feelings; efforts to avoid external reminders such as people, places or conversations |
| Arousal | Sleep disturbance; irritable behavior or angry outbursts; hypervigilance; problems with concentration; exaggerated startle response |
Criteria C to E: duration, impact and exclusions
The disturbance lasts from three days to one month after the trauma. Symptoms usually begin immediately, but must persist for at least three days. The symptoms cause clinically significant distress or impairment in social, work or other important areas of life. They are not better explained by the effects of a substance, another medical condition such as a head injury, or brief psychotic disorder.
ASD vs. PTSD vs. Normal Trauma Response
| Normal stress reaction | Acute stress disorder | PTSD | |
|---|---|---|---|
| Timing | Hours to days, usually easing | 3 days to 1 month | More than 1 month |
| Symptom pattern | Varied and fluctuating distress | 9 or more of 14 symptoms from any category | Required minimum numbers in each of four clusters |
| Impact on daily life | Temporary disruption | Clinically significant distress or impairment | Clinically significant distress or impairment |
ASD vs. PTSD
The main difference is timing. The symptom lists overlap heavily, but PTSD requires symptoms from each of four clusters (intrusion, avoidance, negative changes in thinking and mood, and arousal), while ASD allows any combination of nine symptoms. Dissociation can be part of both; in PTSD it is recorded as a "with dissociative symptoms" specifier. Our guide to PTSD covers the longer-term condition.
ASD vs. normal trauma response
Many people have intrusive memories, disrupted sleep, jumpiness and emotional ups and downs in the days after a frightening event. This does not mean they have a disorder. ASD is distinguished by the number of symptoms, their persistence beyond the first days, and the degree of distress or impairment.
ASD vs. adjustment disorder
Some stressful events, such as a painful divorce or job loss, do not meet Criterion A because they do not involve actual or threatened death, serious injury or sexual violence. When these events lead to significant distress, clinicians may consider an adjustment disorder instead. Adjustment disorder can also apply after a Criterion A event if the person's reactions do not meet ASD or PTSD criteria.
ASD vs. brief psychotic disorder and head injury
If trauma is followed by psychotic symptoms such as hallucinations or delusions, clinicians may consider brief psychotic disorder. Dissociation in ASD can be intense but differs from psychosis. Mild traumatic brain injury (concussion) can also follow accidents, assaults and combat, and some symptoms, such as poor concentration, irritability and sleep problems, overlap. Clinicians assess both possibilities, since they can occur together.
Symptoms in Detail
Intrusion in the acute phase
Intrusive memories in the early weeks can be vivid and fragmented. Sensory details, such as a sound, a smell or a body sensation, may return unexpectedly. People often describe the event as feeling very close, as if it had only just happened. See flashbacks and intrusive thoughts for more on these experiences.
Dissociation
Dissociation means a disruption in the usual integration of awareness, memory and perception. After trauma, people may describe feeling unreal or detached, watching themselves from outside, experiencing time as slowed or speeded up, or the world looking strange. Some cannot recall key parts of the event. Dissociation is a common short-term response; persistent dissociation is one of several factors studied as a risk marker for later PTSD. Our guide to dissociation explains the concept further.
Negative mood
Some people find they cannot feel happiness, affection or interest, even in situations that would normally bring pleasure. This can overlap with depression but in ASD is tied to the onset of the trauma.
Avoidance
Avoidance can develop quickly: steering clear of the place where something happened, news coverage, certain people, or thoughts about the event. In the short term it can reduce distress, but research on anxiety and trauma suggests that persistent avoidance is one of the factors that can keep symptoms going, because it prevents the memory from being processed and fears from being updated.
Hyperarousal
The body's threat system can remain on alert, linked to the fight-or-flight response. Sleep may be broken by nightmares, startle reactions can be exaggerated, concentration may suffer, and irritability can strain relationships at a time when social support is especially valuable.
Who Develops ASD
Rates of ASD vary widely depending on the type of trauma and the population studied. Reviews have reported rates under 10% after some accidents and much higher rates after interpersonal violence such as assault. Researchers have identified several factors associated with higher risk. These are group-level associations and do not predict what will happen to any individual.
Event-related factors
- Greater severity of the event and closer proximity to it.
- Interpersonal violence, including sexual violence, compared with accidents or natural disasters.
- Perceiving one's life to be in danger.
- Injury, or the death or injury of others during the event.
Personal and social factors
- Previous trauma exposure and previous mental health difficulties.
- Lower levels of social support after the event.
- Additional stressors in the following weeks, such as financial or legal problems.
- Higher rates have been reported among women in many studies.
What predicts later PTSD
Research by Richard Bryant and others suggests that ASD on its own is an imperfect predictor of PTSD. Factors that appear consistently across studies include persistent avoidance, strongly negative interpretations of the event and one's reactions (for example, "I'm permanently damaged" or "the world is completely unsafe"), ongoing stress, and lack of support. These overlap with the targets of the cognitive behavioral approaches described below.
Assessment
Assessment is carried out by a qualified clinician, such as a psychologist, psychiatrist or primary care doctor. It usually covers what happened, current symptoms, how the person is functioning day to day, any previous trauma or mental health history, social support, alcohol or substance use, physical injuries, and safety, including any thoughts of self-harm.
Standardized tools
Clinicians and researchers may use structured measures such as the Acute Stress Disorder Interview (ASDI), a clinician-administered interview, or the Acute Stress Disorder Scale (ASDS), a self-report questionnaire, both developed by Richard Bryant and colleagues. Brief screening tools for PTSD symptoms are also used in primary care and emergency settings. These tools support clinical judgment; they do not provide a diagnosis on their own. See our overview of mental health screening for how screeners are used and their limits.
Medical evaluation
Because traumatic events often involve physical injury, clinicians may also check for concussion, pain, the effects of substances or medical treatment, and other physical causes that can produce or worsen symptoms such as poor sleep and concentration.
Evidence-Based Treatment
Treatment decisions are made individually with a qualified professional. The following summarizes what research has found.
Brief trauma-focused cognitive behavioral therapy
The intervention with the strongest research support for people with ASD is brief trauma-focused cognitive behavioral therapy, typically around five to ten sessions. In a series of randomized trials beginning in the late 1990s, Richard Bryant and colleagues found that people with ASD who received trauma-focused CBT were less likely to meet PTSD criteria at follow-up than those who received supportive counseling. Typical components include education about common trauma reactions, gradual and supported recall of the trauma memory, gradually approaching safe situations that have been avoided, and examining unhelpful beliefs about the event. Systematic reviews, including Cochrane reviews of early psychological interventions, support this approach for people with significant symptoms, while noting that the evidence comes from a limited number of trials.
Other approaches
Adapted forms of prolonged exposure have been studied in the early weeks after trauma, with some promising results. EMDR has also been explored as an early intervention, though the evidence base in the acute phase is smaller than for trauma-focused CBT. Medication is one option a doctor may discuss in some circumstances, for example when sleep problems are severe, but guidelines generally recommend psychological approaches as the first step for acute stress reactions, and decisions about medication should be made with a prescribing clinician.
Active monitoring
Because many people recover naturally, guidelines such as those from the UK's National Institute for Health and Care Excellence (NICE) describe active monitoring for people with milder symptoms in the first weeks: checking in again after a short period rather than starting treatment straight away. This respects natural recovery while making sure people who continue to struggle are offered help.
What Research Advises Against
Routine psychological debriefing
Single-session debriefings, in which everyone exposed to an event is asked to describe it and their emotions in detail soon afterward, were widely used in the 1990s. Systematic reviews, including a Cochrane review by Rose and colleagues, found that this approach did not prevent PTSD and, in some studies, was associated with worse outcomes. Major guidelines no longer recommend routine debriefing for everyone exposed to trauma. Instead, psychological first aid focuses on safety, calm, connection and practical support without pressing people to recount the event.
Pressuring people to talk
Pushing someone to describe a traumatic experience in detail before they are ready, especially outside a structured therapeutic setting, can increase distress. Trauma-focused therapies approach memories gradually and with support.
Minimizing or rushing recovery
Comments like "you should be over it by now" are unhelpful, especially in the first weeks. Feeling pressure to appear recovered can increase shame and avoidance.
Wellbeing in the First Month
The general practices below are commonly recommended in public health guidance after stressful events. They support wellbeing but are not a treatment for ASD; anyone whose symptoms are severe, getting worse or not easing after a few weeks should contact a doctor or mental health professional.
- Routine: keeping regular times for meals, sleep and daily activities, even when sleep is broken, can provide structure. Our sleep hygiene guide covers general sleep habits.
- Connection: spending time with trusted people is consistently linked with better outcomes after trauma; brief, regular contact can help as much as long conversations.
- Alcohol and substances: health services generally advise caution, as alcohol and drugs can disrupt sleep and make distress harder to manage.
- Gentle activity: walking or other light exercise may support sleep and mood.
- Media exposure: research after events such as the 2013 Boston Marathon bombing found that many hours of media coverage were associated with higher acute stress, so limiting repeated viewing may help.
Supporting Someone After Trauma
What tends to help
- Being present and available without forcing conversation.
- Listening and believing what the person chooses to share.
- Offering practical help, such as meals, errands or childcare.
- Helping maintain predictable routines.
- Gently encouraging professional support if difficulties persist. Our guide on how to support someone has more ideas.
What tends not to help
- Pushing for details of the event.
- Offering your own theories about what happened or what they should have done.
- Minimizing the experience or comparing it to others'.
- Encouraging alcohol or other substances as a way of coping.
- Expecting a quick return to normal.
When to seek urgent help
Professional help should be sought promptly if a person talks about suicide or self-harm, cannot manage basic daily tasks, is using alcohol or drugs heavily, or remains in danger, for example from ongoing violence. In an emergency, contact local emergency services; our crisis resources page lists support lines.
Summary
Acute stress disorder describes severe trauma-related symptoms in the period between three days and one month after a traumatic event. It overlaps with PTSD but is not the same thing, and many people with ASD recover. Research supports brief trauma-focused cognitive behavioral therapy for people with significant symptoms, active monitoring for milder reactions, and psychological first aid rather than routine debriefing in the immediate aftermath. Most people's reactions ease over time, and social support is one of the most consistent protective factors. Anyone struggling after a traumatic event can speak to a doctor or licensed mental health professional, and our guide to trauma and PTSD explains the wider topic.
Frequently asked questions
What is the difference between acute stress disorder and PTSD?
The main difference is timing. Acute stress disorder covers symptoms lasting from three days to one month after a traumatic event, while PTSD can only be diagnosed once symptoms have lasted more than a month. The symptoms overlap, but PTSD requires symptoms from each of four clusters, whereas ASD requires any nine of fourteen symptoms. Many people with ASD recover without developing PTSD.
How long does acute stress disorder last?
By definition, ASD lasts between three days and one month after the traumatic event. Many people's symptoms ease during this period. If significant symptoms continue beyond a month, a clinician will assess whether PTSD, an adjustment disorder or another condition better describes what the person is experiencing, so that appropriate support can be discussed.
Is it normal to feel shaken for days after a traumatic event?
Yes. Shock, fear, intrusive memories, disturbed sleep, irritability and feeling numb or unreal are very common in the first days after a frightening event, and for many people these reactions gradually ease. ICD-11 describes this as an acute stress reaction, a normal response. If reactions are severe, are getting worse, or aren't easing after a few weeks, it is sensible to speak to a doctor.
Does everyone who goes through trauma need therapy?
No. Research shows that most people exposed to trauma recover without formal treatment, and guidelines recommend against routine debriefing for everyone exposed. For people with milder symptoms, clinicians may suggest active monitoring. For people with significant symptoms, such as those meeting criteria for ASD, brief trauma-focused cognitive behavioral therapy has the strongest research support.
Is acute stress disorder in the ICD-11?
Not as a mental disorder. ICD-11, the World Health Organization's classification, lists acute stress reaction among factors influencing health status and describes it as a normal response to an exceptionally stressful event that typically begins to subside within days. The DSM-5-TR, used widely in the United States, does include acute stress disorder as a diagnosis.
Sources
- American Psychiatric Association. (2022). Diagnostic and Statistical Manual of Mental Disorders (5th ed., text rev.; DSM-5-TR).
- World Health Organization. (2019/2022). International Classification of Diseases, 11th Revision (ICD-11).
- Bryant, R. A. (2017). Acute stress disorder. Current Opinion in Psychology, 14, 127–131.
- Bryant, R. A., Harvey, A. G., Dang, S. T., Sackville, T., & Basten, C. (1998). Treatment of acute stress disorder: A comparison of cognitive-behavioral therapy and supportive counseling. Journal of Consulting and Clinical Psychology, 66(5), 862–866.
- Rose, S., Bisson, J., Churchill, R., & Wessely, S. (2002). Psychological debriefing for preventing post traumatic stress disorder (PTSD). Cochrane Database of Systematic Reviews.
- National Institute for Health and Care Excellence. (2018). Post-traumatic stress disorder (NICE guideline NG116).
- Holman, E. A., Garfin, D. R., & Silver, R. C. (2014). Media's role in broadcasting acute stress following the Boston Marathon bombings. Proceedings of the National Academy of Sciences, 111(1), 93–98.