The aim of this paper is to determine, according to the reviewed literature, the changes in the mental health of nurses and the factors that influenced the aforementioned during the COVID-19 pandemic. The MEDLINE database via PubMed was used to create this paper, after filtering the results 11, more precisely 19, studies remained, among which one prospective study and four meta-analyses, or systematic reviews, were selected. Poor mental health outcomes for nurses due to the pandemic have been identified; almost half of the respondents (about 40%) were exposed to high levels of stress, which has a cause-and-effect relationship with sleep difficulties, about one third of the respondents suffered from anxiety and/or depression, and about 19% of the respondents showed symptoms of PTSD. The phenomenon of adaptation to the newly created situation was also noticed; part of the respondents showed signs of improved mental health after a certain time, which is shown in detail through five synthesized findings. Health services should provide psychological help to their employees; by applying healthy coping skills and therapeutic interventions, nurses will be able to free themselves from the negative effects of the pandemic. Accordingly, emphasis on the importance of mental health should be encouraged during the education of health workers.