Post-traumatic stress disorder (PTSD) is characterized as a serious mental illness that some people experience after witnessing or being involved with a traumatic event, such as a fire, a war, serious accident, or the like. Often, people with PTSD have persistent frightening thoughts and memories of their ordeal and feel emotionally numb, especially with people they were once close to.

No matter what trauma was experienced or witnessed, people with PTSD usually experience flashbacks — intrusive memories or nightmares of the event. They may also experience sleep problems, depression, feeling detached or numb, or being easily startled.

A person who has experience posttraumatic stress disorder may lose interest in things they used to enjoy and have trouble feeling affectionate. They may feel irritable, more aggressive than before, or even violent. Seeing things that remind them of the incident may be very distressing, which could lead them to avoid certain places or situations that bring back those memories. Anniversaries of the event are often very difficult.

Ordinary events can serve as reminders of the trauma and trigger flashbacks or intrusive images. A flashback may make the person lose touch with reality and reenact the event for a period of seconds or hours or, very rarely, days. A person having a flashback, which can come in the form of images, sounds, smells, or feelings, usually believes that the traumatic event is happening all over again.

Not every traumatized person gets full-blown PTSD, or experiences PTSD at all. Post-traumatic stress disorder is diagnosed only if the symptoms last more than a month. In those who do have PTSD, symptoms usually begin within 3 months of the trauma, and the course of the illness varies. Some people recover within 6 months, others have symptoms that last much longer. In some cases, the condition may be chronic. Occasionally, the illness doesn’t show up until months, or even years, after the traumatic event.

Whether the traumatic event is experienced or witnessed, one of the defining characteristics of posttraumatic stress disorder (PTSD) is that the event involves the actual or perceived threat of serious injury or death to the person or others. Traumatic events can include, but are not limited to, the following:

  • Human violence (e.g., rape, physical assault, domestic violence, kidnapping or violence associated with military combat)
  • Natural disasters (e.g., floods, earthquakes, tornadoes or hurricanes)
  • Accidents involving injury or death
  • Sudden, unexpected death of a family member or friend
  • Diagnosis of a life threatening illness

It should be emphasized that most people who are exposed to traumatic events do not develop PTSD and many people with symptoms after a trauma show gradual improvement with time.

However, in some cases, PTSD symptoms may be present and negatively impact on the person’s life (for example, impairing work, studies or relationships with others). In such cases, PTSD may be present. Persons with posttraumatic stress disorder commonly display three types of symptoms:

  • Intrusive re-experiencing symptoms are when a person has memories, flashbacks or nightmares of the event(s).
  • Avoidant or numbing symptoms are when a person withdraws from people or activities that are reminders of the traumatic event.
  • Hyperarousal symptoms are when a person is easily startled, irritable, on edge or has trouble falling asleep.

When children have PTSD, symptoms are expressed in different ways. For example, children may re-experience the traumatic event through repetitive play (e.g., a child who witnessed a robbery may reenact the robbery again and again using her toys).

Researchers have suggested that PTSD tends to be more intense and lasts longer when the traumatic event involves human violence. They have also found good evidence that the likelihood of developing PTSD increases with the severity, length and proximity of exposure to the traumatic event.

According to The American Psychiatric Association’s official diagnostic manual, a person has chronic PTSD if symptoms last for three months or longer. When PTSD symptoms last less than three months, this is considered acute PTSD. It may also be noted that in some people, PTSD symptoms can begin long after the traumatic event, which is called “delayed-onset PTSD.”