Borderline personality disorder affects how you feel about yourself, how you relate to others and how you behave.

Signs and symptoms may include:

• An intense fear of abandonment, even going to extreme measures to avoid real or imagined separation or rejection
• A pattern of unstable intense relationships, such as idealizing someone one moment and then suddenly believing the person doesn't care enough or is cruel
• Rapid changes in self-identity and self-image that include shifting goals and values, and seeing yourself as bad or as if you don't exist at all
• Periods of stress-related paranoia and loss of contact with reality, lasting from a few minutes to a few hours
• Impulsive and risky behavior, such as gambling, reckless driving, unsafe sex, spending sprees, binge eating or drug abuse, or sabotaging success by suddenly quitting a good job or ending a positive relationship
• Suicidal threats or behavior or self-injury, often in response to fear of separation or rejection
• Wide mood swings lasting from a few hours to a few days, which can include intense happiness, irritability, shame or anxiety
• Ongoing feelings of emptiness
• Inappropriate, intense anger, such as frequently losing your temper, being sarcastic or bitter, or having physical fights

As with other mental health disorders, the causes of borderline personality disorder aren't fully understood. In addition to environmental factors — such as a history of child abuse or neglect — borderline personality disorder may be linked to:

• Genetics. Some studies of twins and families suggest that personality disorders may be inherited or strongly associated with other mental health disorders among family members.
• Brain abnormalities. Some research has shown changes in certain areas of the brain involved in emotion regulation, impulsivity and aggression. In addition, certain brain chemicals that help regulate mood, such as serotonin, may not function properly.

Some factors related to personality development can increase the risk of developing borderline personality disorder. These include:

• Hereditary predisposition. You may be at a higher risk if a close relative — your mother, father, brother or sister — has the same or a similar disorder.
• Stressful childhood. Many people with the disorder report being sexually or physically abused or neglected during childhood. Some people have lost or were separated from a parent or close caregiver when they were young or had parents or caregivers with substance misuse or other mental health issues. Others have been exposed to hostile conflict and unstable family relationships.

Borderline personality disorder can damage many areas of your life. It can negatively affect intimate relationships, jobs, school, social activities and self-image, resulting in:

• Repeated job changes or losses
• Not completing an education
• Multiple legal issues, such as jail time
• Conflict-filled relationships, marital stress or divorce
• Self-injury, such as cutting or burning, and frequent hospitalizations
• Involvement in abusive relationships
• Unplanned pregnancies, sexually transmitted infections, motor vehicle accidents and physical fights due to impulsive and risky behavior
• Attempted or completed suicide

In addition, you may have other mental health disorders, such as:

• Depression
• Alcohol or other substance misuse
• Anxiety disorders
• Eating disorders
• Bipolar disorder
• Post-traumatic stress disorder (PTSD)
• Attention-deficit/hyperactivity disorder (ADHD)
• Other personality disorders