Borderline personality disorder (BPD) is a serious mental illness characterized by instability of moods and behavior. Seemingly mundane events may trigger intense symptoms for BPD patients. Symptoms include emotional instability, impulsivity, and poor self-image and social functioning. Those experiencing BPD may go through very short bouts of intense anger, anxiety, and depression that last only hours or days. Patients rapidly change moods within a matter of hours and often experience paranoia and intense dissociation from oneself and from reality. Although the exact cause of BPD is unknown, treatment can be successful in reducing symptoms and improving quality of life. Treatment can consist of multiple forms of psychotherapy, such cognitive-behavioral therapy and dialectical behavior therapy, as well as pharmacological treatment.