The present invention provides methods for treating depression in a patient, comprising administering to the patient in need of the treatment a therapeutically effective amount of esketamine. In some embodiments, the depression is major depressive disorder or treatment resistant depression. In other embodiments, the therapeutically effective amount is clinically proven safe and/or effective. Also provided are methods to mitigate the risk or misuse or abuse of esketamine, instructions for use of the esketamine product, and methods for selling a drug product containing esketamine.