Merck Manual

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Borderline Personality Disorder (BPD)


Mark Zimmerman

, MD, Rhode Island Hospital

Reviewed/Revised May 2021 | Modified Sep 2022

Borderline personality disorder is characterized by a pervasive pattern of instability in relationships, self-image, moods, and behavior and hypersensitivity to possible rejection and abandonment.

  • People with borderline personality disorder fear rejection and abandonment, partly because they do not want to be alone.

  • Doctors diagnose borderline personality disorder based on specific symptoms, including frequently changing relationships, self-image, and mood and self-destructive, impulsive behavior.

  • Psychotherapy can reduce suicidal behaviors, help relieve depression, and help people with this disorder function better, but drugs are sometimes used to lessen symptoms.

People with borderline personality disorder often have difficulty tolerating being alone and may resort to self-destructive actions to cope with or to avoid being alone. They may make frantic efforts to avoid abandonment, including creating crises. For example, they may attempt suicide as a way to communicate their distress and to get other people to rescue and care for them.

Estimates of how common borderline personality disorder vary. It probably occurs in between 2% to almost 6% of the general population in the United States. It is diagnosed more often in women than in men. With time, symptoms tend to lessen in most people.

Other disorders are also often present. They include

Causes of BPD

Genes and environmental factors may contribute to the development of borderline personality disorder.

Certain people may have a genetic tendency to react poorly to life stresses, making them more likely to develop borderline personality disorder as well as other mental disorders. Also, borderline personality disorder tends to run in families, further suggesting that this tendency may be partly inherited. First-degree relatives of people with this disorder are 5 times more likely to have the disorder than the general population.

Stresses during early childhood may contribute to the development of borderline personality disorder. Many people with borderline personality disorder were physically or sexually abused, separated from caregivers, and/or lost a parent when they were children. The insecurity of their attachment to their caregivers contributes to the symptoms of borderline personality disorder.

Symptoms of BPD

People with borderline personality disorder often appear more stable than they feel inside.

Fear of abandonment

People with borderline personality disorder fear abandonment, partly because they do not want to be alone. Sometimes they feel that they do not exist at all, often when they do not have someone who cares for them. They often feel empty inside.

When people with this disorder feel that they are about to be abandoned, they typically become fearful and angry. For example, they may become panicky or furious when someone important to them is a few minutes late or cancels an engagement. They assume these missteps are caused by how the person feels about them rather than by unrelated circumstances. They may believe that a cancelled engagement means the other person rejects them and that they are bad. The intensity of their reaction reflects their sensitivity to rejection.

People with borderline personality disorder can empathize with and care for another person but only if they feel that other person will be there for them whenever needed. Although they desire intimate relationships and care for others, it is difficult for them to sustain stable relationships. They tend to have very high expectations of how the people they feel close to should act, and their feelings about a relationship may fluctuate rapidly and intensely.


People with borderline personality disorder have difficulty controlling their anger and often become inappropriately and intensely angry. They may express their anger with biting sarcasm, bitterness, or angry tirades. Their anger is often directed at close friends, romantic partners, family members, and sometimes doctors because they feel neglected or abandoned.

After the outburst, they often feel ashamed and guilty, reinforcing their feeling of being bad.


People with borderline personality disorder tend to change their view of others abruptly and dramatically. For example, they may idealize someone early in the relationship, spend a lot of time together, and share everything. Suddenly, they may feel that the person does not care enough and become disillusioned. Then they may belittle or become angry with the person.

They may be needy one minute and righteously angry about being mistreated the next. Their attitude fluctuates based on their perception of the availability and support of the others. When feeling supported, they can be vulnerable and needy, and when feeling threatened or let down, they can become angry and devalue others.

People with borderline personality disorder may also abruptly and dramatically change their self-image, shown by suddenly changing their goals, values, opinions, careers, or friends.

The changes in mood usually last only a few hours and rarely last more than a few days. Mood may change because people with this disorder are so sensitive to signs of rejection or criticism in their relationships.

Impulsive behavior and self-harm

Many people with borderline personality disorder act impulsively, often resulting in self-harm. They may gamble, engage in unsafe sex, binge eat, drive recklessly, have substance use problems, or overspend.

Suicide-related behaviors Suicidal Behavior Suicide is death caused by an intentional act of self-harm that is designed to be lethal. Suicidal behavior includes completed suicide, attempted suicide, and suicidal ideation. Suicide usually... read more , including suicidal attempts and threats and self-injury Nonsuicidal Self-Injury Nonsuicidal self-injury is a self-inflicted act that causes pain or superficial damage but is not intended to cause death. Although the methods people use to hurt themselves, such as cutting... read more (for example, by cutting or burning themselves), are very common. Although many of these self-destructive acts are not intended to end life, risk of suicide in these people is 40 times that of the general population. About 8 to 10% of people with borderline personality disorder die by suicide. These self-destructive acts are often triggered by rejection, perceived abandonment, or by disappointment in someone they are close to. People may also harm themselves to express their feelings of being bad or to revive their ability to feel when they are not feeling real or feeling detached from themselves (called dissociation Depersonalization/Derealization Disorder Depersonalization/derealization disorder involves a persistent or recurring feeling of being detached from one’s body or mental processes, like an outside observer of one's life (depersonalization)... read more ). Sometimes, people with borderline personality disorder engage in self-harm to distract themselves from painful emotions.

Other symptoms

People with borderline personality disorder often sabotage themselves when they are about to reach a goal, so that others will perceive them as struggling. For example, they may drop out of school just before graduation or ruin a promising relationship.

When these people feel very stressed, they may have brief episodes of paranoia, symptoms that resemble psychosis (such as hallucinations), or dissociation. The stress is usually caused by feeling that no one cares for them (that is, feeling abandoned and alone) or feeling broken and worthless. Dissociation Depersonalization/Derealization Disorder Depersonalization/derealization disorder involves a persistent or recurring feeling of being detached from one’s body or mental processes, like an outside observer of one's life (depersonalization)... read more includes not feeling real (called derealization) or feeling detached from their body or thoughts (called depersonalization). These episodes are temporary and usually not severe enough to be considered a separate disorder.

Diagnosis of BPD

  • A doctor's evaluation, based on specific criteria

Doctors usually diagnose personality disorders based on criteria in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5 Classification and Diagnosis of Mental Illness In 1980, the American Psychiatric Association published the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III), marking the first attempt to approach the diagnosis... read more ), published by the American Psychiatric Association.

For doctors to diagnose borderline personality disorder, people must have a history of unstable relationships, self-image, and mood, and act impulsively, as shown by at least five of the following:

  • They make desperate efforts to avoid abandonment (actual or imagined).

  • They have unstable, intense relationships that alternate between idealizing and devaluing the other person.

  • They frequently change their self-image or sense of self.

  • They act impulsively in at least two areas that could cause them harm (such as unsafe sex, binge eating, or reckless driving)

  • They repeatedly engage in suicide-related behavior, including attempting or threatening to commit suicide and hurting themselves.

  • They have rapid changes in mood, which last usually only a few hours and rarely more than a few days.

  • They chronically feel empty.

  • They become inappropriately and intensely angry or have problems controlling anger.

  • They have temporary paranoid thoughts or severe dissociative symptoms (feeling unreal or detached from themselves), triggered by stress.

Also, symptoms must have begun by early adulthood.

Prognosis for BPD

In most people with borderline personality disorder, symptoms lessen dramatically and often resolve. However, these improvements do not necessarily translate into being able to maintain stable relationships or to hold a job. Treatments aim to help people function better as well as to reduce symptoms. However, symptoms typically improve more than overall function.

Treatment of BPD

  • Psychotherapy

  • Drugs

Identifying and treating coexisting disorders is important for effective treatment of borderline personality disorder.

Treatment includes psychotherapy and certain drugs.


The main treatment for borderline personality disorder is psychotherapy. Specific psychotherapies for borderline personality disorder can reduce suicide-related behaviors, help relieve depression, and help people function better.

These therapies include the following:

  • Dialectical behavioral therapy

  • Systems training for emotional predictability and problem solving (STEPPS)

  • Mentalization-based treatment

  • Transference-focused psychotherapy

  • Schema-focused therapy

  • General psychiatric management

Dialectical behavioral therapy provides weekly individual and group sessions and a therapist who is also available by telephone. The therapist acts as a behavior coach. The aim is to help people find better ways of responding to stress—for example, to resist urges to behave self-destructively.

STEPPS involves weekly group sessions for 20 weeks. People learn skills to manage their emotions, to challenge their negative expectations, and to better care for themselves. For example, they learn to distance themselves from what they are feeling at the moment. They learn to set goals, avoid illegal substances, and improve their eating, sleeping, and exercise habits. People are also asked to identify a support team of friends, family members, and health care practitioners who are willing to coach them when they are in crisis.

Mentalization refers to people's ability to reflect on and understand their own state of mind (what they are feeling and why) and the state of mind of others. Mentalization-based treatment helps people do the following:

  • Effectively regulate their emotions (for example, calm down when they are upset)

  • Understand how they contribute to their own problems and difficulties with others

  • Reflect on and understand how other people are thinking and feeling

It thus helps them relate to others with empathy and compassion, which also helps others understand and support them.

Transference-focused psychotherapy centers on the interaction between the person and the therapist. The therapist asks questions and helps the person examine exaggerated, distorted, and unrealistic self-images and reactions to various situations. The current moment (including how the person is relating to the therapist) is emphasized rather than the past. For example, when a timid, quiet person suddenly becomes hostile and argumentative, the therapist may ask whether the person noticed a shift in feelings and then ask the person to think about how the person was experiencing the therapist and self when things changed. The purposes are

  • To enable the person to develop a more stable and realistic sense of self and others

  • To learn to relate to others in a healthier way through transference to the therapist

Schema-focused therapy focuses on identifying lifelong maladaptive patterns of thinking, feeling, behaving, and coping (called schemas) and replacing negative thoughts, feelings, and behaviors with healthier ones.

General psychiatric management is designed for the general practitioner, rather than a specialist. It uses individual therapy once a week and sometimes drugs. To enhance self-reliance, therapy prioritizes the ability to work over improving relationships. It also teaches people with borderline personality disorder how to make sense of their symptoms and to understand what the goals and expected results of treatment are.

Supportive psychotherapy is also useful. The therapist's goal is to establish an emotional, encouraging, supportive relationship with the person and thus help the person develop healthy defense mechanisms, especially in interpersonal relationships. However, supportive treatments alone may not reduce the more immediate problems of borderline personality disorder (such as suicidal behavior and self-harm) as effectively as the other, more specific psychotherapies for borderline personality disorder.


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