Persons with PTSD often have other disorders as well, which makes it difficult for clinicians to diagnose the PTSD. In particular, major depression and substance abuse are common in people with PTSD. There may also be an increased risk of panic disorder, agoraphobia, obsessive-compulsive disorder, social phobia and somatization disorder. Scientists are not sure to what extent these co-occurring disorders are present before or come after the traumatic event and the development of PTSD.

When exposure to trauma has been long-standing (as for badly abused children), persons may develop certain enduring patterns of behavior or traits. These include difficulty in trusting others, irregular moods, impulsive behavior, shame, decreased self-esteem and unstable relationships. Many of these traits are also seen in persons with borderline personality disorder, and people with this disorder often have histories of childhood physical and sexual abuse, which are possible causes for PTSD.

Persons with posttraumatic stress disorder (PTSD) also often have physical symptoms. They may go to a primary care physician with many physical complaints, rather than psychological concerns. Studies have also shown that people with PTSD are at increased risk for a number of medical conditions, such as hypertension and asthma.

Significant interpersonal difficulties are common in persons with PTSD. Symptoms of estrangement, irritability and anger, or associated depression, may take their toll on a person’s relationships. Persons with PTSD may find it difficult to talk about symptoms with those who did not go through the same trauma. Sometimes, guilt about surviving or about acts done in order to survive can also cause increased isolation and tension in interpersonal relationships.