Borderline personality disorder is a mental-health condition that affects emotional regulation, self-image, behaviour and relationships. Symptoms vary between people and can improve substantially with appropriate treatment and support.
Possible features
- Emotions that feel intense and change quickly
- Strong fear of rejection or abandonment
- Unstable or conflict-filled relationships
- An uncertain or rapidly changing sense of self
- Impulsive actions that may cause harm
- Feelings of emptiness, anger or shame
- Self-harm, suicidal thoughts or brief stress-related dissociation
These experiences can overlap with trauma-related conditions, depression, bipolar disorder, anxiety, ADHD, substance-use disorders and eating disorders. Diagnosis requires a careful specialist assessment rather than a checklist alone.
Assessment
A qualified mental-health professional considers long-term patterns, current difficulties, personal history, strengths, safety and other possible conditions. The assessment should be respectful and collaborative. A diagnosis should never be used to blame or dismiss a person.
Treatment
Structured psychotherapy is the main treatment. Approaches may include dialectical behaviour therapy, mentalisation-based treatment and other evidence-based therapies. Treatment can help with emotional regulation, relationships, impulsivity and self-harm. Medicines do not treat the disorder itself but may sometimes be used for a coexisting condition or a specific short-term symptom.
Self-management and support
A crisis plan, regular routines, sleep, avoiding alcohol or drugs that worsen impulsivity, grounding skills and support from trusted people can help. Family members and carers may also benefit from education and support while respecting the person’s privacy and independence.
When to seek urgent help
Seek immediate help if you may harm yourself or someone else, cannot stay safe, have taken an overdose or are experiencing a severe mental-health crisis. Call emergency services when there is immediate danger or a serious medical emergency.
Sources
- NHS: Borderline personality disorder
- NHS: Borderline personality disorder treatment
- National Institute of Mental Health: Borderline Personality Disorder
Reviewed: 28 August 2026