Despite the fact that today most of the patients with psychological disturbances assume some form of psychotropic drug treatment, clinical psychologists may have little familiarity with psychopharmacology and are substantially unaware of subtle and yet pervasive potential effects of medications in clinical presentations. In their training, psychologists are generally exposed, at best, to some general principles of drug action. Standard psychopharmacology textbooks tend to omit the subtle psychological changes that may occur during psychotropic drug treatment. Clinical pharmacopsychology consists of the application of clinical psychology to the full understanding of pharmacological effects. The domains of clinical pharmacopsychology encompass the clinical benefits of psychotropic drugs, the characteristics that predict responsiveness to treatment, the vulnerabilities induced by treatment (side effects, behavioural toxicity, iatrogenic comorbidity), and the interactions between drug treatment and psychological variables. The DSM-5 refers to a patient population that no longer exists: subjects who display various manifestations of psychological distress who do not receive any form of drug treatment for it. Any type of psychotropic drug treatment, particularly after long-term use, may increase the risk of experiencing additional psychopathological problems that do not necessarily subside with discontinuation of the drug. The changes may be persistent and not limited to a short phase, such as in the case of withdrawal reactions, and cannot be subsumed under the generic rubrics of adverse events or side effects.