This guideline makes recommendations for the treatment and management of borderline personality disorder in adults and young people (under the age of 18) who meet criteria for the diagnosis in primary, secondary and tertiary care. The guideline also covers the treatment and management of people diagnosed with emotionally unstable personality disorder based on ICD-10 criteria

Borderline personality disorder is characterised by significant instability of interpersonal relationships, self-image and mood, and impulsive behaviour. There is a pattern of sometimes rapid fluctuation from periods of confidence to despair, with fear of abandonment and rejection, and a strong tendency towards suicidal thinking and self-harm. Transient psychotic symptoms, including brief delusions and hallucinations, may also be present. It is also associated with substantial impairment of social, psychological and occupational functioning and quality of life. People with borderline personality disorder are particularly at risk of suicide.

The extent of the emotional and behavioural problems experienced by people with borderline personality disorder varies considerably. Some people with borderline personality disorder are able to sustain some relationships and occupational activities. People with more severe forms experience very high levels of emotional distress. They have repeated crises, which can involve self-harm and impulsive aggression. They also have high levels of comorbidity, including other personality disorders, and are frequent users of psychiatric and acute hospital emergency services. While the general principles of management referred to in this guideline are intended for all people with borderline personality disorder, the treatment recommendations are directed primarily at those with more severe forms of the disorder.

Borderline personality disorder is present in just under 1% of the population, and is most common in early adulthood. Women present to services more often than men. Borderline personality disorder is often not formally diagnosed before the age of 18, but the features of the disorder can be identified earlier. Its course is variable and although many people recover over time, some people may continue to experience social and interpersonal difficulties.

Borderline personality disorder is often comorbid with depression, anxiety, eating disorders, post-traumatic stress disorder, alcohol and drug misuse, and bipolar disorder (the symptoms of which are often confused with borderline personality disorder). This guideline does not cover the separate management of comorbid conditions.

People with borderline personality disorder have sometimes been excluded from any health or social care services because of their diagnosis. This may be because staff lack the confidence and skills to work with this group of people.

This guideline draws on the best available evidence. However, there are significant limitations to the evidence base, notably, few randomised controlled trials (RCTs) of interventions, which have few outcomes in common. Some of the limitations are addressed in the research recommendations.

At the time of publication (January 2009), no drug has UK marketing authorisation for the treatment of borderline personality disorder, but this guideline contains recommendations about the use of drugs to manage crises, comorbid conditions and insomnia. The guideline assumes that prescribers will use a drug's summary of product characteristics to inform their decisions for each person.

NICE has developed a guideline on antisocial personality disorder: prevention and management.