Introduction: The diagnosis of borderline personality disorder is complex as is its pharmacologic treatment. Lamotrigine may offer promise in the treatment of this condition.

Objective: To assess the use of lamotrigine to treat symptoms of affective instability in patients with borderline personality disorder.

Methods: Charts of patients treated with lamotrigine in a private practice during the period of 2003–2004 were reviewed. Patients were included in the analysis if they had been given a clinical diagnosis of borderline personality disorder as defined in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-Text Revision, had continued to display affective instability while taking their previous medications before being treated with lamotrigine; had received a Clinical Global Impression-Severity score before and after lamotrigine therapy; had been treated with lamotrigine, as monotherapy or adjunctive therapy, at a dose ranging from 50–200 mg/day; and continued to take lamotrigine for at least 3 months.

Results: The charts of 13 patients were reviewed and included in the analysis. All patients were female, 19–43 years of age, and had reported continuing symptoms of affective instability despite treatment with two to seven psychotropic drugs, including, but not limited to, fluoxetine, paroxetine, escitalopram, buproprion, and clonazepan. The duration of lamotrigine treatment, before the end of the period covered by the chart review was 3–15 months. The patients had initial Clinical Global Impression-Severity scores of 5 or 6 and a final scores of 1 or 2, except for one patient with an initial score of 3 and a final score of 1 and one patient with an initial score of 6 and a final score of 7.

Conclusion: Lamotrigine seems to be a safe and effective option for the treatment of patients with symptoms of affective instability associated with borderline personality disorder.