Psychiatryniche
A 29-year-old woman with borderline personality disorder has been in dialectical behaviour therapy for four months. Her self-harm has fallen from weekly to once in the past two months. She reports that her mood still swings several times a day with what is happening between her and her friends. There is no sustained low mood, her sleep, appetite and weight are unchanged, and she has no psychotic symptoms. She takes no medicines and is not using contraception. Her general practitioner asks whether a mood stabiliser should be added. Which one of the following is the most appropriate management of her mood instability?