Borderline personality disorder: symptoms, causes and treatment

Key points

• Borderline personality disorder (BPD) is a diagnosis for a long-standing pattern of difficulty with emotions, self-image, impulses and relationships [2].
• UK services also call it emotionally unstable personality disorder (EUPD), and ICD-11 uses a severity rating with a borderline pattern qualifier [7][8].
• BPD is not untreatable. In a 16-year follow-up of 290 patients, 99% reached at least a two-year period of remission [6].
• NICE recommends structured psychological therapy, and says drug treatment should not be used specifically for BPD or its individual symptoms [1].
• It is often confused with bipolar disorder and complex PTSD, and most people diagnosed report childhood trauma or neglect [2][9][10].

What borderline personality disorder is

Borderline personality disorder is a mental health diagnosis given when someone has a long-standing pattern of intense, rapidly changing emotions, an unsteady sense of who they are, impulsive behaviour, and relationships that swing between extremes. The NHS calls it a disorder of mood and of how a person relates to others, and the most commonly recognised personality disorder [2].

If you need help now. Samaritans: call 116 123, free, 24/7. Shout: text 85258. NHS 111, then choose the mental health option. Call 999 if anyone is in immediate danger.

Three labels describe the same thing. BPD and emotionally unstable personality disorder (EUPD) are used interchangeably in the UK, and EUPD appears often in NHS records [8]. ICD-11, the classification the NHS uses, has replaced the separate personality disorder types with a severity rating plus trait descriptions, and keeps a borderline pattern qualifier [7].

The Adult Psychiatric Morbidity Survey 2023/4 found that 1.9% of adults aged 16 and over in England screened positive for BPD, 2.5% of women and 1.3% of men [5]. Screening positive is not a diagnosis.

Symptoms

The NHS groups symptoms into four areas: emotional instability, disturbed thinking or perception, impulsive behaviour, and intense but unstable relationships [2]. They usually appear in adolescence and range from mild to severe [2].

Emotions and sense of self:

• intense feelings such as rage, sorrow, shame or panic that shift quickly [2]
• long stretches of feeling empty [8]
• an unclear or changing sense of identity [8]
• anger that feels out of proportion and hard to control [8]

Thinking and perception:

• suspicious thoughts, or feeling detached from oneself, under stress [8]
• brief unusual experiences, such as hearing a voice for a few minutes [2]

Behaviour:

• self-harm, and thoughts of suicide [8]
• impulsive acts that carry risk, such as heavy drinking, drug use or spending [8]

Relationships:

• a strong fear of being abandoned [8]
• closeness and conflict alternating, sometimes within a single day [2]

Self-harm and suicidal thoughts are part of the diagnostic picture [1]. The pattern is commonly mistaken for bipolar disorder or complex PTSD [9][10].

Types

Borderline personality disorder has no recognised subtypes. What differs is the label, so this section sets out the three systems a UK reader may meet.

• Borderline personality disorder (BPD). The DSM-5-TR category, listing nine features including fear of abandonment, unstable relationships, identity difficulty, impulsivity, self-harm, emptiness and anger, and at least five are needed [8].
• Emotionally unstable personality disorder (EUPD). The ICD-10 name, still widely used in NHS services and meaning the same thing in UK practice [8].
• ICD-11 personality disorder with borderline pattern. ICD-11 rates severity as mild, moderate or severe, adds trait descriptions such as negative affectivity, detachment and disinhibition, then allows a borderline pattern qualifier [7].

Most people see BPD or EUPD on their paperwork [8].

Causes and risk factors

There is no single cause. The NHS states that the causes are unclear and that BPD appears to result from a combination of genetic and environmental factors [2].

• Family history. Inherited risk is thought to play a part, though no specific gene has been identified [8].
• Brain differences. Differences have been described in areas involved in regulating emotion and decision-making, though they describe groups, not individuals [8].
• Childhood adversity. Most people diagnosed have experienced trauma or neglect in childhood [2]. NICE notes that many people using these services have experienced rejection, abuse and trauma [1].

Two common beliefs are not supported. The diagnosis is not a statement about someone’s character, and borderline does not mean a person is close to something worse: it is an old term that stayed in use [2].

How it is diagnosed

A GP is usually the first step. If BPD is suspected the GP refers to a community mental health team, where the assessment is normally carried out by a specialist in personality disorders, usually a psychologist or psychiatrist [3].

The assessment is a conversation, not a test: there is no blood test or scan. The clinician asks about thoughts and feelings, what a person finds easy and difficult, and how they are managing day to day [3].

NICE advises primary care to consider referral when someone has repeatedly self-harmed, shown persistent risk-taking or marked emotional instability [1]. Anyone under 18 goes to CAMHS [1]. No reliable national figure for waiting times exists, and waits vary by area.

A diagnosis describes a pattern and points to the treatments researched for it [1].

Treatment

NICE recommends structured psychological therapy as the main treatment, and advises against brief interventions of less than three months’ duration for BPD [1].

• Dialectical behaviour therapy (DBT). NICE says a full DBT programme should be considered for women for whom reducing repeated self-harm is a priority [1]. That wording reflects the trials available when the guideline was written in 2009, and NHS services offer DBT more widely than it implies. It combines weekly individual sessions, group skills sessions and telephone contact during a crisis [4].
• Mentalisation-based therapy (MBT). Builds the ability to recognise what is going on in one’s own mind and in other people’s. A course usually lasts around 18 months [4].
• Therapeutic communities and arts therapies. Structured group settings and creative therapies are offered in some NHS services [4].

On medication, NICE is direct: drug treatment should not be used specifically for BPD or for the individual symptoms or behaviour associated with it, and antipsychotics should not be used for medium or long-term treatment [1]. Short-term sedative medication may be considered cautiously in a crisis, for no longer than one week [1]. No medicine is licensed in the UK for BPD, although medication may be prescribed for a separate condition such as depression [4]. Any change is a decision for the person and their prescriber.

Living with borderline personality disorder

Ask your team for a written crisis plan. NICE says it should name the triggers that lead to a crisis, the self-management strategies that work for you, and how to reach services when those are not enough [1].

Changes of therapist or team are difficult. NICE says endings and transfers should be discussed with you beforehand and phased rather than abrupt [1].

You can decide how much to tell an employer or university. You do not need to give a diagnosis to ask for adjustments such as predictable hours or time off for appointments.

When to speak to a professional

Make a GP appointment if intense emotions, impulsive behaviour or unstable relationships have lasted months and are affecting your work, study, family life or safety [2].

Ask for referral to a community mental health team if you have self-harmed more than once, are taking risks that worry you, or your emotions shift intensely several times a day [1]. Under 18, the route is CAMHS [1].

If you are told you cannot be helped because of this diagnosis, NICE says otherwise: people with BPD should not be excluded from any health or social care service because of their diagnosis or self-harm [1].

Get urgent help the same day if you are thinking about ending your life or cannot keep yourself safe. Samaritans: 116 123. Shout: text 85258. NHS 111, then the mental health option. Call 999 in an emergency.

Common questions

Is BPD the same as bipolar disorder?

No. Bipolar mood episodes last days or weeks. In BPD, mood shifts are intense, short-lived and can happen several times a day, often triggered by something in a relationship [9]. The two need different treatments, and can occur together: around 20% of people with bipolar II and 10% with bipolar I also have BPD [9].

Is BPD the same as complex PTSD?

No, although they overlap and both are often linked with trauma. ICD-11 keeps them separate. One small study of 97 women found the clearest differences were trauma-related: more trauma exposure, more severe post-traumatic symptoms and more dissociation in the complex PTSD group [10]. Some people meet the criteria for both.

Can you recover from borderline personality disorder?

The evidence is more positive than the diagnosis’s reputation suggests. In a 16-year study of 290 patients, 99% achieved at least a two-year period of symptom remission [6]. Recovery defined more strictly, to include social and working life, was attained by 60% for at least two years and by 40% for at least eight years [6].

Why do people say BPD is a stigmatised diagnosis?

Because people who hold it report being treated as difficult rather than unwell. Rethink Mental Illness records that people with BPD have sometimes been excluded from NHS services because of their diagnosis [8]. NICE guidance states that this should not happen [1].

Clinical review pending

References

1. National Institute for Health and Care Excellence. Borderline personality disorder: recognition and management. NICE clinical guideline CG78, published 28 January 2009. https://www.nice.org.uk/guidance/cg78/chapter/Recommendations
2. NHS. Overview: Borderline personality disorder. nhs.uk, page last reviewed 4 November 2022, review due 4 November 2025. https://www.nhs.uk/mental-health/conditions/borderline-personality-disorder/overview/
3. NHS. Diagnosis: Borderline personality disorder. nhs.uk, page last reviewed 4 November 2022, review due 4 November 2025. https://www.nhs.uk/mental-health/conditions/borderline-personality-disorder/diagnosis/
4. NHS. Treatment: Borderline personality disorder. nhs.uk, page last reviewed 4 November 2022, review due 4 November 2025. https://www.nhs.uk/mental-health/conditions/borderline-personality-disorder/treatment/
5. NHS England Digital. Adult Psychiatric Morbidity Survey: Survey of Mental Health and Wellbeing, England, 2023/4. Chapter 8: Personality disorder, published 27 November 2025. https://digital.nhs.uk/data-and-information/publications/statistical/adult-psychiatric-morbidity-survey/survey-of-mental-health-and-wellbeing-england-2023-24/personality-disorder
6. Zanarini MC, Frankenburg FR, Reich DB, Fitzmaurice G. Attainment and stability of sustained symptomatic remission and recovery among patients with borderline personality disorder and axis II comparison subjects: a 16-year prospective follow-up study. American Journal of Psychiatry, 2012, volume 169, issue 5, pages 476 to 483. https://psychiatryonline.org/doi/10.1176/appi.ajp.2011.11101550
7. Bach B, Kramer U, Doering S, et al. The ICD-11 classification of personality disorders: a European perspective on challenges and opportunities. Borderline Personality Disorder and Emotion Dysregulation, 2022, volume 9, article 12. https://link.springer.com/article/10.1186/s40479-022-00182-0
8. Rethink Mental Illness. Borderline personality disorder (BPD) / Emotionally unstable personality disorder (EUPD): symptoms and treatment. rethink.org. https://www.rethink.org/advice-and-information/about-mental-illness/mental-health-conditions/borderline-personality-disorder-bpd/
9. Bipolar UK. Bipolar and borderline personality disorder (BPD). bipolaruk.org. https://www.bipolaruk.org/about-bipolar/other-conditions/borderline-personality-disorder-BPD/
10. Simon JJ, Spiegler K, Coulibaly K, et al. Beyond diagnosis: symptom patterns across complex PTSD and borderline personality disorder. Frontiers in Psychiatry, 2025, volume 16, article 1668821. https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2025.1668821/full