The International Classification of Diseases, 10th Edition (ICD-10), is a widely used diagnostic system in the UK, and it provides a set of criteria for diagnosing Borderline Personality Disorder (BPD).

In the ICD-10, BPD is referred to as Emotionally Unstable Personality Disorder. The diagnostic code for this disorder is F60.3. The criteria for Emotionally Unstable Personality Disorder in ICD-10 include:

1. Marked tendency to act unexpectedly and without consideration of the consequences: This criterion reflects impulsivity and a lack of regard for the potential negative outcomes of one’s actions.
2. Marked and persistent instability of mood: Individuals with this disorder may experience intense and rapid mood swings, leading to emotional instability.
3. Interpersonal relationships that are often characterized by alternating between extremes of idealization and devaluation: This criterion captures the pattern of unstable and intense relationships commonly seen in BPD, where individuals may rapidly shift between idealizing and devaluing others.
4. Disturbances in and uncertainty about self-image, aims, and internal preferences: This criterion reflects the identity disturbance characteristic of BPD, where individuals may struggle with a clear understanding of their self-image, goals, and values.
5. Chronic feelings of emptiness: Similar to the DSM-5 criteria, ICD-10 includes a criterion for chronic feelings of emptiness as a characteristic of emotionally unstable personality disorder.
6. Inappropriate, intense anger or difficulty controlling anger: This criterion captures the difficulty individuals with BPD have in managing and expressing anger appropriately.
7. Transient, stress-related paranoid ideation or severe dissociative symptoms: Similar to DSM-5, ICD-10 includes criteria related to stress-related paranoid thoughts or severe dissociative symptoms in response to stress.

The diagnostic criteria for BPD are outlined in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which is a widely used classification system for mental health disorders – it is mostly used in the US but is also referred to here in the UK. The criteria include:

1. Frantic efforts to avoid real or imagined abandonment: Individuals with BPD may go to extreme lengths to avoid being abandoned by friends or loved ones. This fear of abandonment can lead to impulsive behaviours, such as self-harm or threats of suicide.
2. A pattern of unstable and intense interpersonal relationships: People with BPD often have tumultuous relationships characterized by extreme idealization and devaluation. They may idolize someone one moment and then quickly shift to feeling intense anger or disappointment.
3. Identity disturbance: Individuals with BPD may have an unstable self-image or sense of self. They may struggle with a lack of a clear understanding of who they are, their values, or their goals.
4. Impulsivity in at least two areas that are potentially self-damaging: This can include reckless driving, substance abuse, binge eating, or other impulsive behaviours that may lead to negative consequences.
5. Recurrent suicidal behaviour, gestures, or threats, or self-mutilating behaviour: People with BPD may engage in self-harming behaviours, such as cutting or burning, or they may have a history of suicidal thoughts or attempts.
6. Affective instability: Individuals with BPD often experience intense and rapidly changing emotions. Mood swings, irritability, and intense episodes of anxiety or depression are common.
7. Chronic feelings of emptiness: People with BPD may describe a persistent sense of emptiness or boredom, and they may have difficulty finding meaning or purpose in life.
8. Inappropriate, intense anger or difficulty controlling anger: Individuals with BPD may struggle to control their anger, leading to frequent outbursts or difficulty in expressing anger in a healthy way.
9. Transient, stress-related paranoid ideation or severe dissociative symptoms: This can involve feeling detached from oneself, experiencing distortions in perception, or having paranoid thoughts, particularly in response to stress.

To receive a diagnosis of BPD, an individual must meet specific criteria outlined in the ICD-10 or DSM-5, and the symptoms must cause significant impairment in social, occupational, or other areas of functioning. It’s important to note that a mental health professional, such as a psychiatrist or psychologist, should conduct a thorough assessment for an accurate diagnosis and appropriate treatment planning.