Post-traumatic stress disorder symptoms may start within one month of a traumatic event, but sometimes symptoms may not appear until years after the event. These symptoms cause significant problems in social or work situations and in relationships. They can also interfere with your ability to go about your normal daily tasks.

PTSD symptoms are generally grouped into four types: intrusive memories, avoidance, negative changes in thinking and mood, and changes in physical and emotional reactions. Symptoms can vary over time or vary from person to person.

Intrusive memories

Symptoms of intrusive memories may include:

• Recurrent, unwanted distressing memories of the traumatic event
• Reliving the traumatic event as if it were happening again (flashbacks)
• Upsetting dreams or nightmares about the traumatic event
• Severe emotional distress or physical reactions to something that reminds you of the traumatic event

Avoidance

Symptoms of avoidance may include:

• Trying to avoid thinking or talking about the traumatic event
• Avoiding places, activities or people that remind you of the traumatic event

Negative changes in thinking and mood

Symptoms of negative changes in thinking and mood may include:

• Negative thoughts about yourself, other people or the world
• Hopelessness about the future
• Memory problems, including not remembering important aspects of the traumatic event
• Difficulty maintaining close relationships
• Feeling detached from family and friends
• Lack of interest in activities you once enjoyed
• Difficulty experiencing positive emotions
• Feeling emotionally numb

Changes in physical and emotional reactions

Symptoms of changes in physical and emotional reactions (also called arousal symptoms) may include:

• Being easily startled or frightened
• Always being on guard for danger
• Self-destructive behavior, such as drinking too much or driving too fast
• Trouble sleeping
• Trouble concentrating
• Irritability, angry outbursts or aggressive behavior
• Overwhelming guilt or shame

For children 6 years old and younger, signs and symptoms may also include:

• Re-enacting the traumatic event or aspects of the traumatic event through play
• Frightening dreams that may or may not include aspects of the traumatic event

Intensity of symptoms

PTSD symptoms can vary in intensity over time. You may have more PTSD symptoms when you're stressed in general, or when you come across reminders of what you went through. For example, you may hear a car backfire and relive combat experiences. Or you may see a report on the news about a sexual assault and feel overcome by memories of your own assault.

You can develop post-traumatic stress disorder when you go through, see or learn about an event involving actual or threatened death, serious injury or sexual violation.

Doctors aren't sure why some people get PTSD. As with most mental health problems, PTSD is probably caused by a complex mix of:

• Stressful experiences, including the amount and severity of trauma you've gone through in your life
• Inherited mental health risks, such as a family history of anxiety and depression
• Inherited features of your personality — often called your temperament
• The way your brain regulates the chemicals and hormones your body releases in response to stress

People of all ages can have post-traumatic stress disorder. However, some factors may make you more likely to develop PTSD after a traumatic event, such as:

• Experiencing intense or long-lasting trauma
• Having experienced other trauma earlier in life, such as childhood abuse
• Having a job that increases your risk of being exposed to traumatic events, such as military personnel and first responders
• Having other mental health problems, such as anxiety or depression
• Having problems with substance misuse, such as excess drinking or drug use
• Lacking a good support system of family and friends
• Having blood relatives with mental health problems, including anxiety or depression

Kinds of traumatic events

The most common events leading to the development of PTSD include:

• Combat exposure
• Childhood physical abuse
• Sexual violence
• Physical assault
• Being threatened with a weapon
• An accident

Many other traumatic events also can lead to PTSD, such as fire, natural disaster, mugging, robbery, plane crash, torture, kidnapping, life-threatening medical diagnosis, terrorist attack, and other extreme or life-threatening events.

Post-traumatic stress disorder can disrupt your whole life ― your job, your relationships, your health and your enjoyment of everyday activities.

Having PTSD may also increase your risk of other mental health problems, such as:

• Depression and anxiety
• Issues with drugs or alcohol use
• Eating disorders
• Suicidal thoughts and actions