OCD & PTSD
Symptoms, Causes & Treatment
Everything you need to know about OCD and PTSD: what they are, what causes them, and the highly effective treatments available.
What Are OCD & PTSD?
OCD and PTSD are two distinct but often co-occurring conditions rooted in anxiety and psychological distress. Both can be profoundly disabling and are frequently misunderstood by the general public. Both respond well to evidence-based treatment when properly diagnosed and managed.
Obsessive-Compulsive Disorder (OCD)
OCD is a chronic mental health condition characterised by two core features: obsessions and compulsions. Obsessions are unwanted, intrusive thoughts, images, or urges that are distressing and difficult to dismiss. Compulsions are repetitive mental or physical acts performed to neutralise the distress caused by obsessions or to prevent a feared outcome. Critically, compulsions provide only temporary relief and ultimately reinforce the obsessional cycle by preventing the person from learning that feared outcomes do not occur.
OCD affects approximately 1–2% of the UK population and affects men and women roughly equally. It typically begins in childhood, adolescence, or early adulthood and tends to be chronic if untreated, though its severity fluctuates over time and with life circumstances.
A common misconception is that OCD is about being "neat and tidy" or "a bit of a perfectionist." In reality, OCD can involve obsessions about harm, contamination, sexuality, religion, morality, or symmetry – and causes significant distress and impairment. The compulsions (which may be mental rather than visible) can consume hours of the person's day.
Post-Traumatic Stress Disorder (PTSD)
PTSD is a psychiatric disorder that can develop following exposure to a traumatic event – one involving actual or threatened death, serious injury, or sexual violence, either as a direct victim, a witness, or in some cases an indirect exposure through learning of trauma to a close person. PTSD affects approximately 4% of adults in the UK at any given time, and lifetime prevalence is considerably higher.
It is important to understand that PTSD is not a sign of weakness and does not only occur after extreme combat trauma. It can develop following any event that overwhelms a person's ability to cope: road traffic accidents, assault, sexual violence, childhood abuse, medical emergencies, natural disasters, or witnessing the serious injury or death of another person. Individual vulnerability plays a significant role – the same event may cause PTSD in one person and not in another.
Complex PTSD (C-PTSD) is a related condition that develops following prolonged, repeated trauma (such as childhood abuse, domestic violence, or torture) and includes additional features beyond standard PTSD, particularly difficulties with emotional regulation, self-perception, and relationships.
What Are the Symptoms of OCD & PTSD?
OCD and PTSD have distinct symptom profiles, though both involve significant anxiety, intrusive mental experiences, and avoidance behaviour. Understanding the difference is important for accessing the right treatment.
- Recurrent, intrusive, unwanted thoughts, images, or urges (obsessions)
- Significant anxiety or distress triggered by obsessions
- Repetitive behaviours or mental acts performed to reduce anxiety (compulsions)
- Common obsessions: contamination, harm, symmetry, forbidden thoughts (sexual or religious)
- Common compulsions: handwashing, checking, counting, ordering, seeking reassurance
- Recognition that obsessions are excessive, but inability to resist them
- Symptoms consuming more than one hour per day and causing significant functional impairment
- Intrusive memories, flashbacks, or nightmares of a traumatic event
- Severe emotional or physical distress when reminded of the trauma
- Avoidance of trauma-related thoughts, feelings, people, or places
- Persistent negative beliefs about oneself, others, or the world
- Feeling detached, numb, or unable to experience positive emotions
- Hypervigilance — constantly on guard for threat
- Exaggerated startle response
- Sleep disturbance, irritability, and difficulty concentrating
- Symptoms lasting more than one month following the traumatic event
Seek immediate help if OCD or PTSD symptoms are accompanied by thoughts of suicide or self-harm — call 999 or go to A&E if in immediate danger, or call the Samaritans on 116 123. Both conditions carry elevated suicide risk, particularly when untreated. OCD symptoms that prevent eating, drinking, or leaving the home, or PTSD symptoms so severe they cause complete inability to function, also require urgent clinical assessment.
What Causes OCD & PTSD?
OCD and PTSD have distinct but partially overlapping causes. OCD is driven primarily by neurological and genetic factors, while PTSD is triggered by trauma exposure in the context of individual and environmental vulnerability factors.
OCD involves dysregulation of circuits connecting the orbitofrontal cortex, anterior cingulate cortex, and basal ganglia — areas involved in error signalling and response inhibition. Serotonin dysfunction is central to OCD pathophysiology, explaining why SSRIs at higher doses than used for depression are effective.
OCD has a strong genetic component, with heritability estimates of 40–65%. Having a first-degree relative with OCD approximately doubles the risk. The condition frequently emerges in childhood or adolescence and can be triggered or worsened by stressful life events.
PTSD develops following exposure to a traumatic event — including combat, sexual assault, serious accidents, natural disasters, childhood abuse, or witnessing death or serious injury. Not everyone who experiences trauma develops PTSD; individual vulnerability, social support, and the nature of the trauma all influence risk.
The brain’s fear memory system — particularly the amygdala and hippocampus — becomes dysregulated after trauma, creating persistent, easily triggered fear responses. The prefrontal cortex, which normally regulates these responses, shows reduced activity, preventing the normal extinction of traumatic memories.
Lack of social support following trauma, ongoing stressors, prior mental health difficulties, dissociation at the time of trauma, and the severity and duration of the traumatic event all significantly increase the risk of developing PTSD.
Both OCD and PTSD frequently co-occur with depression, anxiety disorders, and substance use. In OCD, compulsions provide short-term relief but maintain and worsen the disorder over time. In PTSD, avoidance behaviour prevents the natural processing of traumatic memories and perpetuates the condition.
Key Risk Factors
How Are OCD & PTSD Diagnosed?
Both OCD and PTSD are diagnosed clinically through structured interviews and validated symptom rating scales. A thorough assessment explores the nature and severity of symptoms, their impact on functioning, relevant history, and comorbid conditions. Both conditions are frequently misdiagnosed or diagnosed late — early recognition and appropriate referral is essential.
How Are OCD & PTSD Treated?
Both OCD and PTSD have clearly defined, NICE-recommended treatments that are highly effective for the majority of people. Psychological therapy is first-line for both conditions. Medication plays an important adjunctive role. Early treatment leads to significantly better outcomes.
Supportive Measures
Alongside formal treatment, a number of self-management strategies support recovery. For OCD: delaying compulsions, reducing reassurance-seeking, and engaging with ERP-based self-help resources. For PTSD: grounding techniques to manage flashbacks, maintaining a regular routine, limiting alcohol use, and gradually re-engaging with previously avoided activities with support. Peer support groups — both in-person and online — can provide invaluable connection with others who understand the experience. For both conditions, good sleep, regular exercise, and a stable daily routine all support the brain’s recovery process.
Long-Term Recovery & Relapse Prevention
Both OCD and PTSD can become chronic without treatment and may relapse even after successful therapy. For OCD, relapse prevention involves continued practice of ERP principles — particularly resisting compulsions — and awareness of early warning signs. Long-term low-dose SSRI maintenance reduces relapse risk. For PTSD, recovery is not always linear; many people experience setbacks, particularly around anniversary dates or exposure to new stressors. Ongoing access to therapy and a strong support network are protective. Complex PTSD requires longer-term specialist care. Neither condition should be managed alone.
When Should You Seek Help for OCD or PTSD?
You or someone you know is in immediate danger of suicide or self-harm · Symptoms are so severe that the person is unable to care for themselves or others · A person with PTSD is in a dissociative crisis or experiencing acute psychotic symptoms · OCD symptoms are severe enough to prevent eating, drinking, or leaving the house.
You are experiencing intrusive, distressing thoughts or compulsive behaviours that are consuming significant time or preventing normal daily activities · You have experienced a traumatic event and are having flashbacks, nightmares, or significant avoidance · OCD or PTSD symptoms are worsening or not improving with self-help · You need a referral for ERP, trauma-focused CBT, or EMDR therapy · Symptoms are accompanied by depression, substance use, or thoughts of self-harm.
How Can You Support Recovery from OCD & PTSD?
OCD and PTSD cannot always be prevented, as they depend on neurological vulnerability and exposure to traumatic events. However, early intervention, appropriate coping strategies, and strong social support significantly improve outcomes and can prevent symptoms from becoming entrenched.
Resisting compulsions — rather than giving in to them — is the core skill in OCD recovery. Each time a compulsion is resisted, anxiety peaks and then naturally subsides, teaching the brain that the feared consequence does not occur. This process, called habituation, is the basis of ERP therapy.
Seeking reassurance — from others or internally — is a compulsion that temporarily reduces anxiety but maintains OCD in the long term. Reducing reassurance-seeking is an important component of ERP and self-management. Trusted people around the person with OCD can also be guided not to provide reassurance.
Talking about the traumatic experience with a trusted person, rather than avoiding all reminders, supports natural emotional processing. Social support from friends, family, or peer support groups is one of the strongest protective factors against the development of PTSD following trauma.
Grounding techniques — such as the 5-4-3-2-1 sensory method, slow breathing, or cold water — help manage acute flashbacks and dissociative episodes in PTSD by anchoring attention to the present moment and reducing the intensity of intrusive re-experiencing.
Both OCD and PTSD respond poorly to avoidance. While avoidance reduces short-term distress, it prevents the brain from learning that feared outcomes do not occur (OCD) or that the trauma is in the past and not currently happening (PTSD). Gradual, supported approach to avoided situations is central to recovery for both conditions.
Early intervention significantly improves outcomes in both OCD and PTSD. On average, people with OCD wait 11–17 years before receiving effective treatment. The sooner appropriate therapy is started, the better the prognosis. Seeking a clinical assessment when symptoms first emerge is the most important protective step.
Speak to a Clinician About OCD and PTSD
OCD and PTSD are serious but highly treatable conditions. Through The GP Service, you can speak to a licensed clinician confidentially — from home. A clinician can assess your symptoms, provide a referral for specialist psychological therapy (ERP, trauma-focused CBT, or EMDR), and prescribe medication where appropriate while you wait for therapy.
Expert clinical advice, when you need it.
OCD & PTSD FAQs
OCD (Obsessive-Compulsive Disorder) is an anxiety-related condition characterised by recurrent, unwanted, intrusive thoughts (obsessions) and repetitive behaviours or mental acts (compulsions) performed to reduce the anxiety they cause. It is not about being a perfectionist or liking things tidy — OCD involves distressing, ego-dystonic thoughts that the person recognises as irrational but feels unable to resist acting on. It affects approximately 2% of the population and can be profoundly disabling when untreated. With appropriate treatment — primarily ERP and SSRIs — the majority of people with OCD experience significant improvement.
Exposure and Response Prevention (ERP) is a form of CBT specifically designed for OCD. It involves gradually exposing yourself to situations that trigger obsessional anxiety — in a planned, hierarchical way — while resisting the urge to perform the associated compulsion. Over time, the brain learns that the anxiety decreases naturally without the compulsion, and that the feared catastrophe does not occur. ERP is the most evidence-based psychological treatment for OCD and is recommended as first-line by NICE. It requires courage and commitment but produces lasting results.
PTSD (Post-Traumatic Stress Disorder) is a mental health condition that can develop after experiencing or witnessing a traumatic event — such as assault, combat, a serious accident, or childhood abuse. It is characterised by intrusive re-experiencing of the trauma (flashbacks, nightmares), avoidance of trauma reminders, negative changes in mood and beliefs, and persistent hyperarousal. It is not a sign of weakness; PTSD is a normal response of a normal nervous system to an abnormal event. It affects approximately 4% of the UK population and is highly treatable.
EMDR (Eye Movement Desensitisation and Reprocessing) is a structured psychotherapy that helps people process traumatic memories by activating the brain’s natural information processing system while the person briefly focuses on the traumatic memory. The therapist uses bilateral stimulation — typically asking the person to follow moving fingers with their eyes — while the person holds the traumatic memory in mind. This appears to activate the same processing that occurs during REM sleep, allowing the traumatic memory to be processed and stored more adaptively. EMDR is a NICE-recommended first-line treatment for PTSD and is at least as effective as trauma-focused CBT.
Complex PTSD (C-PTSD) is a more severe and pervasive form of PTSD that develops following prolonged, repeated trauma — particularly in situations where escape is difficult or impossible, such as childhood abuse, domestic violence, or prolonged captivity. In addition to the core PTSD symptoms, C-PTSD is characterised by significant difficulties with emotional regulation, negative self-perception, and relationship difficulties. It requires specialist trauma-informed treatment and often takes longer to treat than single-incident PTSD.
Both OCD and PTSD carry elevated risk of depression, anxiety, substance misuse, and suicidal ideation. People with OCD often experience profound shame and secrecy around their symptoms, which delays help-seeking. People with PTSD may use alcohol or drugs to manage intrusive symptoms, which worsens long-term outcomes. If you or someone you know is experiencing OCD or PTSD alongside thoughts of self-harm or suicide, seek urgent clinical support. Call the Samaritans on 116 123 or contact your GP for same-day assessment.
Many people with OCD worry that their intrusive thoughts — including violent, sexual, or blasphemous thoughts — make them dangerous or morally deficient. In reality, the content of OCD obsessions is the opposite of what the person wants. Someone with OCD about harming others is not a violent person; the thought causes distress precisely because it conflicts with their values. Intrusive thoughts of this nature are extremely common in the general population and do not predict behaviour. In OCD, it is the response to the thought — not the thought itself — that is the problem.
In the UK, you can access treatment for OCD and PTSD via your GP (referral to IAPT or secondary mental health services), self-referral to NHS Talking Therapies (IAPT), private therapy with a specialist CBT or EMDR therapist, or via charities such as OCD-UK, MIND, and Combat Stress (for veterans). Waiting times via the NHS can be long; private therapy provides faster access. A clinician can help you navigate the options, provide a referral letter, and prescribe medication where appropriate while you wait for therapy.