The focus of this research was to explore school leadership in post-primary schools using an adapted Schmidt Toxic Leadership Scale ©, which the authors recalibrated to examine both constructive and destructive leadership, the impact on individuals professional and personal lives, and on staff morale. Using a mixed methods approach, data were collected from 111 teaching professionals via online survey. Findings indicated a notable emergence of toxic leadership experiences which is reported in this paper. In addition, participants reported various and concerning negative consequences including: decreased job satisfaction, professional agency, and staff morale; reduced performance; increased attrition; increased negative behaviours including incivility; stifled career development; reduced self-confidence; depression; stress and anxiety; fear; tearfulness; humiliation; anger; mistrust; exhaustion; burnout; health issues; migraines; weight gain; substance abuse, suicidal thoughts, as well as, negative consequences on personal/home life. The results indicate that the quality of leadership was perceived to influence the health of respondents and had a bearing on their occupational wellbeing. Further research is needed to understand the nature of toxic leadership in education and its effects on organisational members.