By Lauren Smith

Last updated: 19 March 2024 & medically reviewed by Dr. Kimberly Langdon

Post-traumatic stress disorder (PTSD) is a mental health condition that follows a traumatic event and causes an overactive fear response, memory issues (flashbacks and gaps), avoidance, and low mood. PTSD impairs daily functioning and can be life-altering but is often responsive to psychotherapy such as CBT, exposure therapy, and eye movement desensitization and reprocessing (EMDR).

Key takeaways:

  • While many people experience short-term symptoms of fear, guilt, and nightmares after traumatic experiences, for those diagnosed with PTSD these symptoms continue for much longer (at least a month after the event) and interfere with their relationships, work, and daily life. 

  • Complex PTSD (C-PTSD) develops in response to prolonged or recurring trauma. C-PTSD is more likely when the trauma was experienced at a young age, when the individual had little or no hope of escaping the trauma.

  • In most people with PTSD, the symptoms emerge within three months of the traumatic experience. But in some people, the symptoms develop more than six months later, and sometimes even years later.

Post-Traumatic Stress Disorder (PTSD)

What is post-traumatic stress disorder (PTSD)?

Post-traumatic stress disorder (PTSD) is a mental health condition triggered by terrifying, dangerous, or distressing experiences such as road traffic accidents, sexual assault, natural disasters, terrorist attacks, and warfare.

While many people experience short-term symptoms of fear, guilt, and nightmares after traumatic experiences, for those diagnosed with PTSD these symptoms continue for much longer (at least a month after the event) and interfere with their relationships, work, and daily life. 

These symptoms include re-experiencing the event through flashbacks and nightmares; avoiding reminders of the event; negative changes in mood and thinking such as hopelessness, guilt, and blame; and changes in physical and emotional reactions, including hypervigilance and feeling constantly on edge.

PTSD develops in around one in three people who experience severe trauma.[1] In the United States, 6.8% of people will experience PTSD at some point in their lifetimes.[2]

In addition to standard PTSD, there are several subtypes.

Complex PTSD

Complex PTSD (C-PTSD) develops in response to prolonged or recurring trauma. C-PTSD is more likely when the trauma was experienced at a young age, when the individual had little or no hope of escaping the trauma, and when it was caused by someone they trusted, such as a parent or caregiver.

Experiences that may trigger C-PTSD include

  • Child abuse (especially physical or sexual), neglect, or abandonment
  • Being the victim of or witnessing prolonged domestic violence
  • Kidnapping and being held hostage
  • Torture
  • Slavery and human trafficking, including being forced or manipulated into sex work
  • Solitary confinement of prisoners
  • Concentration camp experiences
  • Genocide
  • War

Symptoms of C-PTSD include those of PTSD but also difficulty controlling emotions, anger, distrust, hopelessness, emptiness, feelings of worthlessness, and difficulties with relationships and friendships. Some symptoms of C-PTSD align with those of borderline personality disorder and some people may be misdiagnosed with BPD.[1][3]

Dissociative subtype

The American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) includes a dissociative subtype of PTSD. When exposed to reminders of the trauma, people with dissociative PTSD people don’t experience hyperarousal symptoms such as accelerated heart rate and sweating typical of people with PTSD. Instead, they present with dissociative symptoms, especially depersonalization and derealization.

  • Depersonalization: the sense of being detached from the self and mental processes or outside of the body. People may feel they are observing themselves from distance or watching a movie of themselves.
  • Derealization: a sense of being disconnected from the surrounding world, with everything feeling unreal, artificial, dream-like, foggy, and visually distorted.

It’s thought that this dissociation is a strategy to limit hyperarousal in PTSD. It’s associated with greater severity of PTSD, early life trauma, and more comorbid mental health conditions and is more prevalent in men.[4][5]

Delayed-onset PTSD

In most people with PTSD, the symptoms emerge within three months of the traumatic experience. But in some people, the symptoms develop more than six months later, and sometimes even years later, leading them to be diagnosed with delayed-onset PTSD.

Symptoms of PTSD

The DSM-5 groups symptoms of PTSD under four headings: intrusion or re-experiencing symptoms, avoidance symptoms, arousal and reactivity symptoms, and cognition and mood symptoms.

Intrusion symptoms

The traumatic event is persistently or recurrently re-experienced in one or more of the following ways:

  • Flashbacks: reliving the traumatic event as if it were happening again
  • Nightmares
  • Unwanted upsetting memories
  • Emotional distress after being exposed to reminders of the event
  • Physical reactions to reminders, such as a racing heart and sweating

Avoidance symptoms

  • Staying away from places, events, or objects that are reminders of the event
  • Avoiding thinking or talking about the event

Arousal and reactivity symptoms

These symptoms begin or worsen after the trauma and are often present continuously, making it difficult to complete daily activities, sleep, and relax. They’re thought to be a result of an increased fight or flight response following trauma.

  • Hypervigilance
  • Feeling tense or on edge
  • Heightened startle response
  • Risky or destructive behavior
  • Irritability, aggression, or angry outbursts
  • Difficulty concentrating
  • Difficulty sleeping

Mood and cognition symptoms

These include negative thoughts and emotions that began or worsened after the trauma:

  • Inability to recall key events of the trauma
  • Negative appraisal of the world and the future, hopelessness
  • Difficulty experiencing positive emotions
  • Emotional numbness
  • Lack of interest in activities previously enjoyed
  • Feeling detached from other people
  • Exaggerated guilt or blame of others for causing the event[6][7]

Symptoms of complex PTSD

Symptoms of C-PTSD include symptoms of PTSD and also:

  • Negative self-concept, including feeling they are worthless, damaged, or evil; guilt; and sometimes having no sense of self
  • Interpersonal difficulties, including avoiding relationships or finding them difficult, never feeling close to another person, feeling that no one can understand what happened to them
  • Interpersonal sensitivity, including difficulty controlling emotions, angry outbursts, feeling distrustful of other people and having their feelings easily hurt
  • Dissociative symptoms, including depersonalization and derealization
  • Physical symptoms, such as headaches, dizziness, chest pains, and stomach aches
  • Suicidal feelings and self-harm[8]

How is PTSD diagnosed?

PTSD is diagnosed by a mental health professional such as a psychiatrist or psychologist. They will discuss your symptoms and the trauma that may have triggered them. They may speak to your family members and close friends about your symptoms too and undertake a physical exam to see to rule out any medical problems that may be causing your symptoms.

Under the DSM-5, PTSD can be diagnosed if:

  • An individual was exposed to death, threatened death, actual or threatened serious injury, or actual or threatened sexual violence, either as the victim or as a witness. Alternatively, they learned a family member or friend was exposed to trauma or they were indirectly exposed to details of a traumatic event, usually in the course of their job (eg. first responders, medics).
  • They experience at least one intrusion symptom.
  • They have at least one avoidance symptom.
  • They have at least two arousal and reactivity symptoms.
  • They have at least two mood and cognition symptoms.
  • The symptoms last for at least a month.
  • The symptoms cause distress or functional impairment, for example in their relationships, social life, work, or education.[9]

What causes PTSD?

PTSD is caused by experiencing or witnessing a frightening or life-threatening event.

These include:

  • Road traffic accidents
  • Rape or sexual assault
  • Abuse including child abuse and intimate partner violence
  • Stalking
  • Harassment and bullying, including motivated by hate, such as racism, sexism, or homophobia
  • Violence, including muggings, robberies, military combat, and terrorist attacks
  • Secondary trauma, such as seeing other people injured or killed, including as part of your job (eg. among people who work in emergency services)
  • Natural disasters such as floods, earthquakes, fires, and pandemics
  • Being kidnapped or held hostage
  • Traumatic childbirth
  • Life-threatening illnesses and hospitalizations
  • Losing someone close, especially in shocking and upsetting circumstances
  • Warfare
  • Torture

Some traumatic events are more likely to trigger PTSD than others, with intimate partner violence or sexual assault having the highest likelihood—especially rape (19% of people exposed will develop PTSD) and physical abuse by a romantic partner (11.4%).[10]

Risk factors

Most people who experience a traumatic event won’t develop PTSD. 

Higher susceptibility to PTSD has been linked to:

  • Genetics, which may account for 5% to 20% of the variation in PTSD risk following a traumatic event[11]
  • Childhood experiences, including trauma and family stressors, especially maternal distress and loss of a parent[12]
  • A history of mental health disorders such as depression, panic disorder, and OCD


During frightening or life-threatening events, the amygdala in the brain signals the body to release the stress hormones adrenaline, norepinephrine, and cortisol, putting us into fight or flight mode. In people with PTSD, this stress response is overactive and creates a neurological pattern in the brain. Even after the danger has passed, a hyperactive amygdala keeps firing, and the prefrontal cortex, which usually pumps the brakes on this fear response, is underactive. That’s why people with PTSD experience overwhelming fear reactions to small reminders of the trauma, have exaggerated fear reactions to harmless situations, and avoid situations that might trigger these responses.[13]

Long-term exposure to these stress hormones, especially cortisol, can damage the brain’s hippocampus, the part responsible for storing and retrieving memories. This leads to the memory problems of PTSD, including the loss of some memories of the traumatic event and the frequent recurrence of other memories through flashbacks and nightmares. Additionally, people with small hippocampi might be more susceptible to developing PTSD.[14]

What treatment options are there for PTSD?

Treatment for PTSD mainly involves a combination of talking therapy (psychotherapy) and medication. 


Trauma-focused psychotherapy is the main treatment for PTSD, with many different modalities used and researched, especially cognitive-behavioral and behavioral therapies.

The American Psychiatric Association recommends as first-line treatments prolonged exposure therapy (PE), cognitive processing therapy, cognitive behavioral therapy (CBT), and cognitive therapy (CT).[15] The Department of Veterans Affairs (VA) recommends PE, CPT, and Eye Movement Desensitisation and Reprocessing (EMDR).[16]

In exposure therapy, the patient is brought into contact with reminders of the traumatic event to desensitize them and weaken the link between the triggers and trauma memories and the intense arousal states of PTSD. The exposure can be:

  • imaginal: for example, the patient recounts the traumatic memory to the therapist multiple times
  • in vivo: in real life. For instance, riding in a car if the trauma was a road traffic accident.
  • interoceptive: in which a triggering feeling is generated physically. For example, running in place to elevate the heart rate.
  • Virtual reality (VRET): use of a computer-generated visual environment. This method is particularly useful for combat veterans because they’re unable to be exposed in vivo to the traumatic event.

Prolonged exposure (PE) therapy combines exposure therapy and other psychotherapy elements in a structured way, in eight to fifteen weekly, 90-minute appointments. As many as 73% of participants may see clinically significant improvement.[17]

Cognitive behavioral therapy (CBT), the patient learns to identify, challenge, and replace negative patterns of thought and behavior and develop coping mechanisms. Unhelpful thought patterns that may be challenged in PTSD include negative thinking, catastrophizing, and overgeneralizing bad outcomes.[18]

Cognitive processing therapy is a type of CBT that teaches patients to challenge and modify unhelpful beliefs about the trauma and reach a new understanding of the traumatic event to reduce its negative impact on their life.[19]

In eye movement desensitization and reprocessing (EMDR) the patient recalls the traumatic experience while experiencing bilateral stimulation (usually side-to-side eye movements or hand-tapping). It’s based on the theory that PTSD emerges because a distressing event wasn’t adequately processed by the brain and aims to change the way memories of it are stored.[20]


Antidepressants, especially SSRIs and SNRIs, are the most commonly prescribed medication for PTSD. However, the effects are small and a meta-study suggests that a combination of psychotherapy and medication is no more effective than psychotherapy alone.[21][22]

Recently there's been interest in the use of the party drug MDMA (ecstasy) to treat PTSD. A randomized controlled trial (RCT) found that one dose of MDMA, paired with psychotherapy, improved symptoms in 88% of participants without adverse effects.[23] It's expected that the FDA will approve the drug for PTSD as early as 2023.[24]

PTSD and substance abuse

PTSD and substance abuse are frequently co-morbid (occurring in the same people). An epidemiological study in the US found that nearly half (46%) of people with PTSD have a substance use disorder. Among patients with substance use disorders, 25 to 34% have PTSD, with the highest rates among those who abuse both drugs and alcohol.[25] 

There are likely several reasons for the overlap between PTSD and addiction. First, people with PTSD may turn to drugs and alcohol to cope with intrusive memories, flashbacks, and other symptoms. Around 20% of people with PTSD report self-medicating in this way.[26] 

People who abuse drugs and alcohol may be more likely to experience trauma because they have riskier lifestyles. Additionally, chronic substance use, including withdrawals, may cause higher levels of arousal anxiety, sensitize neurobiological stress systems, and enhance fear conditioning.[27] Heavy alcohol use may also impede the psychological processes of working through trauma and becoming desensitized to reminders of it.[28]

There’s also an overlap in the risk factors for PTSD and substance abuse, including childhood trauma. Some genes that code for PTSD liability may also code for vulnerability to addiction: twin studies reveal an estimated 40% overlap in the genetic influences for PTSD and alcohol, drug, and nicotine dependence.[29]

Substance abuse and PTSD can complicate treatment for each other and lead to poorer outcomes such as more frequent drug relapses. Most mental health professionals recommend they be treated simultaneously. Research backs this up: patients who receive PTSD treatment and substance abuse treatment in the first three months of intervention were 3.7 times more likely to be free of substances five years later compared to those only treated for addiction.[30]

Getting help for PTSD

Treatment can significantly improve the severity and duration of symptoms of PTSD, especially when it’s prompt.

If you’re a veteran, the VA can help you find specialized PTSD programs in your area.

The PTSD Foundation of America can help veterans and first responders access support groups and information. It runs a helpline at 1-877-717-PTSD (7873).

If you’re experiencing PTSD following sexual assault, you can contact RAINN's National Sexual Assault Hotline at 1-800-656-HOPE (4673).