Pharmacogenetic testing (PGx) is an important diagnostic tool for achieving an optimal balance between the effectiveness and safety of psychotropic drugs, especially those requiring long-term use. The most prescribed medications in psychiatric practice are antipsychotics (APs). Despite the long period of use of APs, their safety profile remains insufficiently high. Due to the high incidence of adverse drug reactions (ADRs), from the central nervous system (CNS) and other organs and tissues of the human body. Therapeutic drug monitoring can help predict and diagnose AP-induced ADRs only if the patient is receiving APs. PGx helps to individually select an AP, its dose and clarify the risk of ADRs before prescribing an AP, or at the start of therapy. This explains the importance of PGx in psychiatrist practice. However, to date, most practicing psychiatrists rarely use predictive PGx or do not use this method. PGx is more often prescribed in the case of a long history of un-successful AP-therapy, or in the case of the development of serious ADRs, the risk of which could be significantly reduced if predictive PGx was used. This case report of PGx in a 56-year-old woman with severe bipolar disorder demonstrates that the trajectory of ADRs and socialization could be significantly improved if this method was prescribed before the initiation of APs, rather than in the event of the development of serious ADRs.