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Complex post-traumatic stress disorder: Diagnosis and treatment
By
Prof Brendan Kelly, Professor of Psychiatry, Trinity College Dublin
- 27th Oct 2025
iStock.com/AndreyPopov
An overview of post-traumatic stress disorder, the diagnostic criteria, options for management, and the challenges with accessing the necessary resources
There is long-standing awareness of the effects of trauma and stressful events on mental health. Diagnostic terminology has changed over time. Most recently, in 2018, the World Health Organisation formally described ‘complex post-traumatic stress disorder’ (PTSD) in its International Classification of Diseases, 11th Revision (ICD-11). This article examines the diagnostic criteria for this condition, options for management, and challenges with accessing the resources that are needed.
The origins of complex PTSD: Traumatic or stressful events
For a diagnosis of complex PTSD, ICD-11 requires exposure to one or more events of an extremely threatening or horrific kind, typically prolonged or repeated, from which escape is difficult or impossible. Examples include torture, imprisonment in concentration camps, slavery, campaigns of genocide, other forms of organised violence, extended domestic abuse, or recurrent sexual or physical abuse during childhood.
The impact of some of these events will vary between people, depending on their circumstances and past experiences. However, most people will experience at least some psychological or psychiatric sequelae from these types of traumas.
For a diagnosis of complex PTSD, ICD-11 requires not only the occurrence of such a traumatic or stressful event or series of events, but also the emergence of all three core elements of standard PTSD, lasting for at least several weeks, as well as additional features which are specific to complex PTSD.
Three core elements of standard PTSD
The first core element of standard PTSD is re-experiencing, which refers to reliving the traumatic event after it has occurred, such that the event is not only recalled, but felt as if it is happening again in the present. This may take the form of vivid intrusive memories or images; flashbacks, ranging from mild (a brief sense that the event is recurring) to severe (a complete loss of awareness of current surroundings), or repetitive dreams and nightmares thematically linked to the trauma.
Such experiences are usually accompanied by intense emotions (eg, fear, horror) and powerful physical sensations. Re-experiencing can also involve becoming overwhelmed by, or immersed in, the intense emotions originally felt during the trauma, even without a strong cognitive component, and may be triggered by reminders of the event. Simply reflecting on or ruminating about the trauma, or recalling the feelings experienced at the time, does not meet the threshold for re-experiencing.
The second core element of PTSD is intentional avoidance of reminders that could trigger re-experiencing of the traumatic event. This may involve active internal efforts to block thoughts or memories of the trauma, or external avoidance of people, conversations, activities, or situations associated with it. In more extreme cases, the individual may even alter their environment (eg, move house, change jobs) in order to reduce exposure to reminders.
The third core element is ongoing perceptions of imminent threat, often shown through hypervigilance or an exaggerated startle response to stimuli such as sudden noises. Individuals who are hypervigilant remain constantly on guard, perceiving themselves or those close to them as being in immediate danger, either in particular situations or more broadly. They may develop new safety behaviours (eg, avoiding sitting with their back to a door, or repeatedly checking a car’s rear-view mirror). In complex PTSD, unlike standard PTSD, the startle response may sometimes be reduced rather than heightened.
For a diagnosis of either standard PTSD or complex PTSD, it is necessary that the resultant disturbance causes marked impairment in personal, family, social, educational, occupational, or other key areas of functioning. Where functioning is preserved, it is only achieved through considerable additional effort.
Additional requirements for complex PTSD
In addition to the above, there are certain additional requirements for a diagnosis of complex PTSD, rather than standard PTSD. According to ICD-11, complex PTSD also requires:
Severe and pervasive difficulties in regulating emotions. These may present as heightened emotional responses to minor stressors, episodes of violent anger, reckless or self-destructive behaviours, dissociative symptoms under stress, or emotional numbing, including a diminished capacity to feel pleasure or positive emotions.
Enduring negative beliefs about oneself as diminished, defeated, or worthless, often accompanied by profound and pervasive feelings of shame, guilt, or failure linked to the traumatic experience. For instance, a person may feel guilty for not escaping or for having succumbed to the adverse situation, or for being unable to prevent the suffering of others.
Ongoing difficulties in maintaining relationships and experiencing a sense of closeness with others. The individual may regularly avoid, dismiss, or show little interest in relationships and social interaction more broadly. In some cases, there may be periods of intense relationships, but these are often difficult to sustain.
Finally, there can also be additional clinical features in complex PTSD which further complicate presentation and diagnosis. These can include suicidal thoughts or behaviours, substance misuse, depressive symptoms, psychotic features, and various somatic complaints.
Management of complex PTSD
The management of complex PTSD draws on evidence-based treatments for standard PTSD, while taking account of the broader disturbances in affect regulation, self-concept, and interpersonal functioning that characterise the condition. Evidence to date supports the use of trauma-focused psychological therapies as first-line interventions, supplemented by additional modalities where clinically indicated.
Trauma-focused cognitive behavioural therapy (TF-CBT) and eye movement desensitisation and reprocessing (EMDR) remain the most widely studied and recommended therapies. TF-CBT assists patients in identifying and modifying maladaptive trauma-related beliefs, reducing avoidance behaviours, and learning strategies to manage intrusive memories and hyperarousal. EMDR, which involves recalling the traumatic incident in detail while making specific eye movements guided by a therapist, has demonstrated efficacy in diminishing the intensity of traumatic memories and improving adaptive processing.
While both TF-CBT and EMDR are effective in complex PTSD, evidence suggests that treatment may need to be longer in duration, more flexible in structure, and combined with skills-based work to address disturbances in self-organisation.
Because many patients with complex PTSD present with pervasive difficulties in emotion regulation, interventions incorporating dialectical behaviour therapy principles or other skills-based therapies can be valuable. These programmes focus on distress tolerance, affect regulation, and interpersonal effectiveness, thereby improving stability and readiness for trauma-focused work. Group-based therapies may also be helpful, providing opportunities to practise relational skills and reduce social isolation, which is often profound in this population.
Complex PTSD is frequently complicated by comorbid depression, anxiety disorders, substance misuse, or medically-unexplained somatic symptoms. These conditions require concurrent management, either through pharmacological treatment, integrated psychosocial interventions, or referral to specialist services. Antidepressant medication, particularly selective serotonin reuptake inhibitors, can provide symptomatic relief for mood and anxiety symptoms and may enhance engagement with psychological therapy. Addressing substance misuse is particularly important, as untreated dependence can undermine progress in trauma-focused work.
Complex PTSD is frequently complicated by comorbid depression, anxiety disorders, substance misuse, or medically unexplained somatic symptoms
Given the chronic and relapsing nature of complex PTSD, it is useful to consider the importance of ongoing support beyond the completion of structured therapy. This may take the form of stepped-down follow-up within specialist services, ongoing input from primary care, or engagement with voluntary sector and peer-support networks. Continued therapeutic contact can help consolidate gains, reduce relapse risk, and provide patients with a sense of stability and safety.
Recovery from complex PTSD is often slower and more variable than in single-event PTSD. However, with appropriately adapted trauma-focused therapy, combined with attention to comorbidities and ongoing support, many patients achieve clinically significant improvements in symptoms and functioning. A collaborative, phased approach – beginning with stabilisation and skills acquisition, progressing to trauma-focused interventions, and concluding with reintegration and consolidation – is supported by clinical evidence and professional opinion.
In summary, management of complex PTSD requires trauma-focused treatment tailored to the complexities of chronic, interpersonal trauma. Effective care typically involves longer, multimodal interventions that extend beyond trauma processing alone. It is also useful to anticipate the need for sustained support and a holistic, person-centred approach into the future.
In Ireland, complex PTSD typically warrants referral to specialist mental health services. Unfortunately, these teams often have limited capacity and may not be able to provide timely access to specialist, evidence-based trauma therapies. In such circumstances, it remains valuable to offer a clear explanation of the condition, validate the person’s experiences, and maximise the use of whatever resources are available. This may include linking with primary care supports, community mental health teams, psychotherapists, voluntary organisations, and peer-support groups. Supporting stability through attention to sleep, substance use, social support, and physical health can also reduce distress and improve resilience.
Conclusions
Complex PTSD is a relatively newly-described concept, building on pre-existing understandings of standard PTSD. While psychiatry needs to be wary of diagnostic expansion, it appears that complex PTSD accurately describes the experiences of a certain group of people who underwent trauma of an exceptionally distressing and affecting nature. It is hoped that the evidence-base for the treatment of complex PTSD will expand in the years ahead, along with the availability of appropriate services to all who need them.
*The case histories described in this article are not based on specific individuals, but are composed to demonstrate common features of complex PTSD.
Case example of features of complex post-traumatic stress disorder
Patrick is a 42-year-old man living in the west of Ireland. He was referred to mental health services by his GP following repeated presentations with insomnia, panic attacks, and physical complaints for which no clear medical explanation could be found.
Patrick’s history revealed a childhood marked by prolonged sexual and physical abuse within the family home. The abuse persisted for years and there was little opportunity to escape. He left school early and, in adulthood, struggled with unstable employment, recurrent relationship difficulties, and long periods of social isolation.
He describes re-experiencing phenomena, including vivid intrusive memories and distressing nightmares in which the abuse replays with full emotional intensity. At times, unexpected reminders such as a raised voice or a sudden noise trigger flashbacks, during which he momentarily feels transported back to the abusive environment. These episodes are accompanied by overwhelming fear and physical sensations such as trembling, palpitations, and shortness of breath.
To manage these experiences, Patrick engages in deliberate avoidance, making considerable efforts to block distressing memories and steering clear of people or conversations that might bring them to mind. He avoids family gatherings, certain television programmes, and even parts of town that remind him of his childhood.
Patrick reports a persistent sense of threat, living in a state of heightened vigilance and constantly scanning his environment for danger. He insists on sitting near exits in public places and often checks his car’s rear-view mirror, fearing he might be followed. Although sometimes startled by loud noises, he has also noticed that his reactions can feel oddly blunted, as though he is numb to danger.
Patrick struggles with difficulties in emotional regulation, describing episodes of explosive anger in response to minor frustrations, followed by periods of emotional shutdown. He admits to reckless behaviours, including heavy drinking and occasional dangerous driving. He experiences long stretches of emotional numbing, during which he feels incapable of experiencing joy or warmth.
Patrick holds deeply entrenched negative beliefs about himself as weak, broken, and undeserving of happiness. Feelings of shame and guilt are pervasive, particularly around not having been able to stop the abuse or protect his younger siblings.
Finally, Patrick describes persistent relational difficulties. He avoids close friendships and has had a series of intense but short-lived romantic relationships, each ending abruptly due to mistrust and withdrawal.
Taken together, Patrick’s presentation is consistent with complex PTSD as defined in ICD-11, with clear evidence of trauma exposure, core symptoms of post-traumatic stress, and the disturbances in self-organisation that characterise complex PTSD.
Case example of presentation and treatment of complex post-traumatic stress disorder
Eileen is a 48-year-old woman. She works part-time in a bookshop and was referred to mental health services after her GP noted increasing isolation, frequent physical complaints, and heavy reliance on sleeping tablets.
Eileen’s difficulties stem from years spent in an institution as a child, where harsh discipline, neglect, and repeated exposure to frightening situations were routine. She recalls long periods of fear, being shouted at, locked in rooms, and seeing other children punished. Although she later lived independently, the sense of having been abandoned and powerless persisted into adulthood.
Eileen describes intrusive re-experiencing, often in the form of vivid images and nightmares of the institution. Passing certain buildings or hearing heavy doors slam can trigger flashbacks in which she feels transported back to childhood.
Eileen uses avoidance strategies, deliberately steering clear of people who grew up in similar circumstances and refusing to talk about her childhood with friends. She rarely visits the area where the institution was located.
Eileen’s sense of ongoing threat is pronounced. She describes constant tension, an exaggerated startle reaction to sudden noises, and a need to plan escape routes whenever she enters a new environment. She always positions herself near doors in cafés and avoids public transport at busy times.
Eileen also struggles with emotional regulation. She becomes overwhelmed by even minor frustrations and, at other times, feels emotionally flat and disconnected. On stressful days, she engages in binge eating and has, in the past, engaged in self-harm.
She carries deeply negative self-beliefs, often describing herself as ‘unwanted’ and ‘defective’. Shame is a dominant theme, and she blames herself for not having managed to cope ‘better’ as a child. Her relationships are limited and fragile. She keeps her distance from others, fearing rejection, but occasionally forms intense attachments that end abruptly when she withdraws.
Eileen engaged in treatment involving a combination of supportive psychotherapy, TF-CBT, and group-based skills training for emotional regulation. An antidepressant was prescribed to help with mood and sleep. Over the course of a year, she began to notice improvements. She developed greater tolerance for her emotions, reduced her reliance on medication for sleep, and slowly reconnected with a small circle of friends.
Although she continues to experience intrusive memories and remains cautious in relationships, Eileen now reports a greater sense of agency and describes her recovery as ‘learning to live without erasing the past’. Her outcome is moderately good, with better functioning and a more hopeful outlook, though significant vulnerabilities remain.
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