Diagnosis of borderline personality disorder requires clinical assessment by a qualified mental health professional. Diagnostic criteria include:

• Intense fear of abandonment
• A persistently unstable self-image
• A pattern of unstable relationships veering between extremes of idealization and devaluation
• Impulsive risky behavior
• Suicidal or self-harming behavior
• Frequent mood swings
• Chronic feelings of emptiness
• Difficulty controlling anger
• Paranoid thinking or dissociative symptoms

For a diagnosis, five or more of the criteria must be present, no later than early adulthood.