This case study analyzes a clinical incident involving an 81-year-old patient, Patient A, admitted to a GP clinic and subsequently a local hospital. The patient's condition deteriorated after being administered Oral Lasix, leading to a cascade of medical errors, including misdiagnosis, lack of effective medication, and professional negligence. The analysis identifies key professional errors, such as improper medication administration, failure to conduct comprehensive assessments, and the unavailability of the treating doctor, which ultimately contributed to the patient's death from septicaemia. The study emphasizes the importance of thorough patient history documentation, comprehensive assessments, appropriate medication management, and adherence to professional standards. The report highlights the need for improved monitoring, efficient nursing plans, and ethical decision-making in critical care settings. The case underscores the implications for future nursing practice, emphasizing the significance of systematic assessments, timely interventions, and the crucial role of communication and collaboration among healthcare professionals to prevent similar incidents.