A risk factor is something that increases your likelihood of getting a disease or condition.

Not everyone who experiences a traumatic event will develop PTSD. Symptoms of PTSD are more likely to occur if a person has the following risk factors:

People who have experienced a previous trauma, such as a rape, car accident, disaster, or act of violence, are more susceptible to PTSD. The stress of the trauma can have a cumulative effect, and a new traumatic experience can exacerbate the negative effects of a previous trauma. This is especially true for those with early and longer-lasting childhood trauma.

People with a history of physical, emotional, or sexual abuse tend to be more susceptible to PTSD. Such experiences contributed to previous trauma and their effects may be reinforced by any additional trauma.

People with a family history of PTSD and/or depression tend to be more susceptible to PTSD. Family history of other mental health problems may also increase the risk.

People with a history of substance abuse tend to be more susceptible to PTSD. It may be that drug use and alcoholism interfere with a person's ability to cope with the added stress of a traumatic event.

Coping skills and the level of psychological functioning can play a role in a person’s susceptibility to PTSD. People are more susceptible to PTSD if they have poor coping skills or lower levels of psychological functioning. They may have little sense of control over their circumstances or blame themselves for the trauma.

Considerable research suggests that positive social and family relationships can help moderate the effects of stress and trauma. Conversely, people who lack supportive relationships and environments tend to be more vulnerable to stress and therefore more at risk for PTSD after experiencing trauma. A social environment that produces shame, guilt, stigmatization, or self-hatred also increase the risk.

The effects of extreme or ongoing stress on a person can result in extensive physical and psychological problems. This can reduce the ability to cope with trauma, therefore increasing the risk of PTSD.