Post-traumatic stress disorder and acute stress disorder

• Post-traumatic stress disorder (PTSD) is a condition that can follow exposure to a very threatening or horrific event, in which the person keeps re-living it, avoids reminders, feels on guard, and has negative changes in mood and thinking, with these symptoms lasting more than one month and causing distress or impairment. ^[4]
• Acute stress disorder (ASD) is essentially the same pattern in the first month after the event: a DSM-5 diagnosis that applies within the first 4 weeks and needs 9 or more symptoms from any of the 5 categories (intrusion, negative mood, dissociation, avoidance, arousal). ^[1]
• Most people exposed to trauma (about 70% worldwide) do not develop PTSD; lifetime prevalence is about 3.9%. ^[3]
• Trauma-focused psychological therapy is the first-line treatment; drug treatment (an SSRI such as sertraline or paroxetine, or venlafaxine) is offered for those who prefer it, and prazosin is a useful add-on for trauma-related nightmares. ^[1][4][5]
• The condition is very treatable, but people who do not seek help, who have repeated trauma or poor social support, are more likely to become chronic. ^[3][4]

By the end of this page you should be able to:

1. Define PTSD and ASD and state how they differ by timing and, in the case of ASD, by symptom count.
2. Describe the four symptom clusters of PTSD and the features of complex PTSD.
3. Give the approximate global prevalence and the conditional risks after common traumas.
4. Recognise PTSD in the mental state examination and carry out a suicide and risk assessment.
5. Distinguish PTSD from acute stress disorder, adjustment disorder, depression, anxiety disorders and malingering.
6. State first-line psychological treatment, the role of EMDR, and when drug treatment is used, with usual doses.
7. Outline the place of prazosin for nightmares and how to start and monitor it.
8. Treat comorbid depression correctly and plan for children, pregnancy and older adults.

Trauma exposure is defined broadly: events such as serious accidents, physical and sexual assault, childhood or domestic abuse, work-related exposure to trauma (including remote exposure), severe health problems or childbirth experiences, war and conflict, and torture can all precipitate the disorder. ^[1] The event may be single or repeated.

Classification sits in the trauma and stressor-related disorders group. PTSD is diagnosed on the basis of criteria in

Around 70% of people worldwide experience a potentially traumatic event at some point, although large national samples have reported lower lifetime exposure (for example 51% of women and 61% of men in a large United States sample). ^[3][4] Of those, only a minority (about 5.6%) develop PTSD, giving a lifetime prevalence of roughly 3.9% of the general population. ^[3][4] Most affected people are exposed through common events such as accidents, bereavement and illness; rates are far higher after intentional violence, particularly sexual violence and exposure to war (up to 15.3% after violent conflict). ^[3][4]

Gender matters: in large surveys lifetime rates were about 8% in men and 20% in women, even though men reported somewhat more exposure to trauma overall. ^[4] Women's higher rate holds across much of the literature. ^[3]

The probability that a given exposure leads to PTSD varies sharply with the type of event: ^[4]

Course is variable: of those who develop PTSD, about one-third recover within the first six months, another third within two years, and one-third go on to chronic PTSD. ^[4] WHO states that up to 40% recover within one year. ^[3] Only about one in four people with PTSD in low- and middle-income countries reports seeking any treatment, so the true burden is larger than service data suggest. ^[3]

Trauma is necessary but not sufficient. Most exposed people do not become ill, which implies that predisposition interacts with the event. ^[4]

Pre-traumatic risk factors include a prior history of mental disorder (depression, anxiety, substance use, previous PTSD), a family psychiatric history, childhood adversity and family dysfunction, female sex, sexual minority status, high neuroticism, and limited social support. ^[4] Twin studies put the heritability of PTSD symptoms at roughly 30 to 70%. ^[4]

Characteristics of the event that raise risk: repeated or prolonged exposure, physical injury during the event, witnessing harm to others, and peritraumatic factors such as dissociation and intense fear. ^[3][4]

Post-traumatic factors that maintain symptoms: subsequent adverse life events, financial or trauma-related loss, repeated reminders, and lack of social support. Conversely, feeling supported by family, friends or peers after the event reduces risk. ^[3][4]

The working model is of an over-sensitised threat system: fear memory is insufficiently regulated, leading to heightened arousal, exaggerated startle, intrusive re-experiencing and hypervigilance, while sleep is fragmented. Research has explored serotonergic and noradrenergic dysregulation and hypothalamic-pituitary-adrenal axis dysfunction, but no reliable biological marker for PTSD has been found, so diagnosis remains clinical. ^[4] Sleep fragmentation both results from and worsens noradrenergic hyperactivity, which is why trauma-related nightmares and hyperarousal often cluster. ^[5][6]

The delayed-onset form (onset more than 6 months after trauma, reported in about 20 to 25% of cases) almost always follows a period of subthreshold symptoms rather than a completely silent interval. ^[4]

A good history covers the trauma itself (what happened, when, how many times, injuries), the interval since it, and the symptoms across four clusters: ^[4]

1. Intrusion - recurrent, involuntary and distressing memories; trauma-related nightmares; dissociative flashbacks in which the event feels as if it is happening again; intense distress on exposure to reminders; physiological reactions to such reminders. ^[4]
2. Avoidance - of memories, thoughts or feelings about the event, and of external reminders such as people, places or conversations. ^[4]
3. Negative alterations in cognition and mood - dissociative amnesia for key details; persistent negative beliefs about self, others or the world; distorted blame of self or others; a persistent negative emotional state (fear, anger, guilt, shame); diminished interest in activities; detachment from others; inability to feel positive emotions. ^[4]
4. Alterations in arousal and reactivity - irritability and angry outbursts, verbal or physical aggression; reckless or self-destructive behaviour; hypervigilance; exaggerated startle; difficulty concentrating; sleep disturbance. ^[4]

Functional impact matters: PTSD usually impairs sleep, work, relationships and social participation; physical symptoms (headache, gastrointestinal upset, palpitations) are common and may dominate in some cultures. ^[3]

Look for a vigilant, easily startled person, often anxious, downcast or emotionally numbed, with restricted affect and a sense of detachment. Cognition is usually normal, though concentration may be poor; insight is usually intact. Hallucinations and delusions are not typical of PTSD itself - their presence suggests a psychotic illness or a severe comorbid depression. Screen throughout for trauma-related guilt and shame, and for complex PTSD features (emotional dysregulation, a sense of worthlessness, difficulty with closeness). ^[4][1]

Suicide risk is a real consideration: people with PTSD have higher rates of suicidal thoughts and behaviours and of harmful alcohol or drug use. ^[3] A risk assessment should cover thoughts of self-harm or harming others, plan and intent, access to means, substance use, protective factors, and a safety plan. ^[1] If a significant risk of harm to self or others is identified, establish a risk management and safety plan as part of initial treatment planning. ^[1]

Malingering should be considered when there is a clear external incentive and a striking mismatch between reported severity and the objective history; prevalence is estimated at about 7.4% in non-forensic evaluations and 16 to 53% in forensic settings. ^[4]

There is no laboratory or imaging test that diagnoses PTSD. Assessment is clinical and comprehensive: psychiatric history including the trauma and timeline, developmental and medical history, substance use, a risk assessment, and attention to physical, psychological and social needs. ^[1][4]

Screening tools are used to quantify symptoms and to track progress. A validated brief instrument such as the PC-PTSD-5 or the IES-R may be used after disasters, and in refugee and asylum-seeker screening, at about 1 month; GP assessment relies on careful questioning of re-experiencing, avoidance, hyperarousal, dissociation, negative mood and thinking changes and function. ^[1] Formal diagnosis and severity are established at interview using structured clinician-rated measures, most commonly the CAPS-5 (Clinician-Administered PTSD Scale for DSM-5), with patient-rated scales (PCL-5) used to monitor change.

PTSD criteria (paraphrased from DSM-5-TR/ICD-11): exposure to actual or threatened death, serious injury or sexual violence, followed by symptoms in four clusters lasting more than one month with clinically significant distress or impairment, with the disturbance not explained by a substance or medical condition. ^[4] Acute stress disorder occupies the same picture within the first month and requires 9 or more symptoms across the 5 categories. ^[1] The at least 1-month duration distinguishes PTSD from a normal acute stress reaction and from ASD. ^[4]

Safety first: treat injuries, ensure physical safety, address sleep and nutrition, and prevent further harm. Early after trauma, offer psychological emergency care (practical help, accurate information, connection with supports) rather than formal debriefing: NICE advises that psychologically-focused debriefing should not be offered for prevention or treatment. ^[1] For subthreshold symptoms within the first month, consider active monitoring, with follow-up within a month. ^[1]

Trauma-focused psychological therapy is the treatment of first choice for children, young people and adults. ^[1][3] NICE recommends offering individual trauma-focused CBT to adults who have ASD or clinically important symptoms within the first month of trauma, and to adults with PTSD presenting after one month: cognitive processing therapy, cognitive therapy for PTSD, narrative exposure therapy or prolonged exposure therapy, typically 8 to 12 sessions based on a validated manual, with a focus on re-establishing normal functioning, typically delivered by a trained practitioner with ongoing supervision. ^[1] NICE also offers EMDR to adults with PTSD or clinically important symptoms presenting more than 3 months after non-combat-related trauma, and between 1 and 3 months if the person prefers it. ^[1] For children, NICE recommends individual trauma-focused CBT adapted to age and development, at 6 to 12 sessions, involving parents or carers; EMDR is used only when trauma-focused CBT is not responded to or engaged with; drug treatments are not used under 18. ^[1]

Guidance differs in how strongly it supports EMDR: NICE offers it to adults presenting more than 3 months after a non-combat-related trauma (and between 1 and 3 months if the person prefers it), the WHO names EMDR among the psychological treatments with the strongest evidence, and the WFSBP grading summarised by Bandelow (2026) found EMDR not superior to active control conditions or psychological placebo. Across these documents trauma-focused CBT remains the first-line psychotherapy and EMDR an established, preference-dependent option. ^[1][3][4]

Drug treatment is a legitimate option, particularly for adults who prefer it, have residual symptoms after psychotherapy, or cannot access trauma-focused therapy. ^[1][4] NICE in the UK recommends considering venlafaxine or an SSRI such as sertraline, noting that only sertraline and paroxetine had a UK licence for PTSD at the time of the guideline; many other agents are off-label. ^[1] The WFSBP grading lists SSRIs (fluoxetine, paroxetine, sertraline) and venlafaxine as first-line, with amitriptyline, imipramine, phenelzine and mirtazapine as alternatives carrying higher side-effect burdens, and risperidone or quetiapine as third-line for the treatment-unresponsive. ^[4] In the USA, sertraline and paroxetine are FDA-approved for PTSD; VA/DoD also recommends paroxetine and venlafaxine. ^{[6] [3]}

Prazosin deserves special handling: it is started at 1 mg (often in the evening) and increased slowly because of first-dose hypotension, especially in people taking beta-blockers or diuretics; slow titration by 1 mg every few days avoids this. ^[6] Effective nightly doses for nightmares are usually titrated into the 3 to 16 mg range, although individual responses at lower doses and safe use up to 30 to 45 mg at bedtime have been reported. ^[6] Paradoxically, some patients need 30 to 45 mg at bedtime, and doses as low as 1 mg have helped. ^[5][6] Monitor blood pressure and orthostatic symptoms; it is useful in people with comorbid headaches or alcohol use disorder. ^[5] Antipsychotics such as risperidone are reserved, as an adjunct to psychological therapy, for disabling hyperarousal or psychotic symptoms that have not responded to other treatment. ^{[1] [4]}

Assess whether treatment is working, re-assess risk, and support transitions between services. ^[1] When PTSD and depression coexist, usually treat PTSD first, because depression often improves with successful PTSD treatment; treat depression first when it is severe enough to make psychological treatment of the PTSD difficult, or when there is a risk of harm to self or others. ^[1] Do not exclude people with PTSD from treatment on the grounds of comorbid drug or alcohol misuse. ^[1] For people with complex PTSD or additional needs (substance misuse, dissociation, emotional dysregulation, interpersonal difficulties, negative self-view), build in extra time and sessions, attend to safety and housing, and plan ongoing support. ^[1]

No medication is recommended to prevent PTSD: NICE advises against drug treatments, including benzodiazepines, for prophylaxis, and hydrocortisone has reduced PTSD symptoms in some placebo-controlled secondary-prevention studies but is not recommended as routine prophylaxis. ^[1][4] Early psychological intervention is targeted: active monitoring for subthreshold symptoms; individual trauma-focused CBT for adults with ASD or clinically important symptoms after recent trauma; for children, active monitoring or individual trauma-focused CBT within 1 month, or group trauma-focused CBT after large-scale shared trauma. Psychologically-focused debriefing is not offered. ^[1]

Refer to specialist mental health services for diagnostic uncertainty, severe or chronic PTSD, suicidal risk, comorbid serious mental illness or substance dependence, complex PTSD, failure to respond to an initial treatment, children and young people, and medicolegal contexts. Emergency assessment is needed for acute suicidality, severe dissociation or psychotic features. ^[1]

• Persistent or recurrent PTSD symptoms, chronic impairment and reduced quality of life. ^[4]
• Comorbid depression, anxiety disorders, substance use, and physical health problems (including cardiovascular risk linked to chronic hyperarousal). ^[3][4]
• Suicide and self-harm risk; harmful use of alcohol or drugs. ^[3]
• Social and occupational disability, family and relationship breakdown. ^[1]
• Medical-legal consequences and compensation issues; malingering in forensic settings. ^[4]

PTSD is treatable. About 40% of people recover within one year, although about one-third go on to a chronic course. ^[3][4] Prognosis is worse with repeated trauma, childhood adversity, comorbid depression or substance use, and ongoing danger or lack of social support; protective factors are social support, early help and evidence-based treatment. Delayed onset occurs in roughly 20 to 25% of cases. ^[4]

Prevention sits mostly before and immediately after trauma: promote social support, practical help and stable environments; active monitoring of subthreshold cases; avoid routine psychological debriefing. ^[1][3] Screening is targeted rather than universal: people at high risk after major disasters (routine validated brief instrument at about 1 month as part of disaster planning), and refugees and asylum seekers at high risk as part of a comprehensive physical and mental health screen. ^[1] Children seen in emergency departments after trauma should have their carers told about normal stress responses and red flags, with advice to contact the GP if symptoms persist beyond one month. ^[1]

Children and adolescents. Symptoms are often behavioural. NICE recommends active monitoring or individual trauma-focused CBT within 1 month for under-18s with ASD or clinically important symptoms, and individual trauma-focused CBT (offer, not consider) after 3 months; group trauma-focused CBT after large-scale shared trauma; no drug treatment at any age under 18. ^[1]

Pregnancy and postpartum. PTSD (including after birth trauma) is treatable; avoid delay in care on the basis of pregnancy, and choose trauma-focused therapy first. Pharmacotherapy in pregnancy is a specialist, case-by-case decision. ^[1][3]

Older adults. PTSD can present late or be missed behind somatic complaints or depression; NICE and the VA/DoD pathways apply. Prazosin for nightmares has been well tolerated by older veterans in reported experience. ^[2][5]

• The diagnosis is clinical; no laboratory test is required. ^[4]
• A validated 5-item screener (PC-PTSD-5 or equivalent) and a clinical interview are practical. ^[1]
• Trauma-focused CBT can be delivered by trained non-specialists with supervision; digital or telephone support is better than none. ^[1]
• Where prazosin and SSRIs are unavailable, prioritise psychoeducation, support, sleep hygiene, and trauma-informed community and peer support. ^[1][3]

PTSD belongs to the trauma and stressor-related disorders alongside ASD and adjustment disorder; it overlaps with depression and anxiety but is best managed, where possible, with trauma-focused therapy first. For broader anxiety context and for obsessive-compulsive spectrum disorders see related reading. (Plain text rather than links.)

• PTSD follows exposure to actual or threatened death, serious injury or sexual violence, with intrusion, avoidance, negative changes in cognition and mood, and hyperarousal lasting more than one month with distress or impairment. ^[4]
• Acute stress disorder applies within the first month and requires 9 or more symptoms from any of the 5 clusters. ^[1]
• Lifetime prevalence is about 3.9%; about 70% of people experience trauma but only about 5.6% develop PTSD; women are affected more often. ^[3]
• Conditional risks range from 5 to 10% after disasters to 30 to 53% after sexual assault. ^[4]
• About a third of cases recover within 6 months, another third within 2 years; about a third become chronic; up to 40% recover within a year. ^[3][4]
• Complex PTSD reflects prolonged or repeated trauma and adds emotional dysregulation, a sense of worthlessness and difficulty sustaining relationships. ^[1]
• Diagnosis is clinical; screen with validated instruments (CAPS-5, PCL-5, PC-PTSD-5) but confirm by interview. ^[1][4]
• Trauma-focused psychological therapy is first-line; drug treatment (an SSRI such as sertraline or paroxetine, or venlafaxine) is an evidence-based alternative. ^[1][4]
• EMDR is an established option after 3 months, or earlier by preference; guidelines disagree about how strongly EMDR outperforms active control conditions. ^[1][3][4]
• Benzodiazepines are not recommended for PTSD. ^[1][4]
• Prazosin 1 mg at night titrated to 3 to 16 mg helps trauma-related nightmares; VA/DoD recommends it for nightmares only. ^[2][5][6]
• Comorbid depression is usually treated second to PTSD unless it is severe or risk is high. ^[1]
• No drug prevents PTSD; no drug is used under 18; psychological debriefing is avoided. ^[1]
• Social support after trauma is one of the clearest modifiable protective factors. ^[3]

PTSD is one of the trauma and stressor-related disorders; see also depression, anxiety disorders, obsessive-compulsive disorder and related disorders, and adjustment disorder when available in the library.