Anisocoria (unequal pupil size) occurring acutely can be indicative of serious neurological pathology. However, in healthcare professionals who handle nebulised medicines, acute anisocoria is often caused by benign conditions such as mydriasis (abnormal pupil dilation) triggered by exposure to certain drugs and occurring unilaterally. This article reports on the case of an emergency nurse who developed acute anisocoria while on shift. It describes the initial assessment and further investigations, outlines the differential diagnosis, and discusses the implications for emergency nursing practice. Drug-induced mydriasis should be considered in healthcare professionals presenting with acute anisocoria, especially in the absence of red-flag symptoms. Increased awareness of this benign and self-limited condition could promote the safer handling of nebulised medicines and a more nuanced application of ‘gloves off’ recommendations.