What is borderline personality disorder?
Borderline personality disorder is a mental illness that causes intense mood swings, impulsive behaviors, and severe problems with relationships and self-worth. People with this disorder often have other problems such as depression, eating disorders, or substance abuse.

Most of the time, signs of the disorder first appear in childhood. But problems often don't start until early adulthood. Treatment can be very hard, and getting better can take years. This is because problems with emotions and behaviors are hard to improve. But treatment may work better than experts used to think. Most people with severe symptoms get better over time.1

What are the symptoms?
Everyone has problems with emotions or behaviors sometimes. But if you have borderline personality disorder, the problems are severe, repeat over a long time, and disrupt your life. The most common symptoms include:

Intense emotions and mood swings.
Impulsive behaviors that are self-damaging, such as substance abuse, binge eating, and reckless driving.
Relationship problems.
Low self-worth.
A frantic fear of being left alone (abandoned).2
Aggressive behavior.
Other symptoms may include:

Feeling empty inside.
Problems with anger, such as violent temper tantrums.
Hurting yourself, such as cutting or burning yourself.
Suicide attempts and suicidal thoughts.