With the impression of DID, aggression risk, and deliberate self-harming behavior, we prescribed mirtazapine 30 mg and risperidone 2 mg. After the first week of treatment, her personality switch decreased, and less aggression or self-harm was noted (A-DES scores: 127). Mild sedation and somnolence side effects were mentioned, but without extrapyramidal side effects. Her mother assisted her in receiving the biological treatment and monitored whether she took these medications because of the possibility of poor medication adherence. She mentioned that her original personality could control her mind and behavior longer after the mirtazapine and risperidone treatment. The other three personalities became diminished after medication treatment. The A-DES scores also decreased from 167 to 45, with significant improvement after 1 month of treatment. The symptoms changed mostly in the dimensions of behavioral control, thought control, body self-awareness, personality-switch frequency and duration, and better ability to recall what she did while another personality manipulated her mind and behavior. Her symptoms maintained stationary (A-DES: 41) under mirtazapine and risperidone combined treatment for the next 6 months until the present, with mild body-weight gain, around 1 kg in these 7 months.