Aim: This study aims to explore the experiences and mediating factors of nurses' responses to electronic device alarms in critical care units (CCUs).Background: Alarm fatigue occasionally has adverse consequences for patient safety.Methods: This qualitative study was designed and analysed following Giorgi's descriptive phenomenological approach. Seventeen nurses were theoretically sampled, reaching information saturation. Semistructured interviews were used to collect the data. Results: Three central themes explained nurses' experiences: general perceptions about alarms (basic equipment of the CCU), strategies to reduce false alarms (training in the configuration of monitors, customization of the alarms to fit he patient's condition. teamwork and taking advantage of the development of technology) and key elements of the response to alarms (information about patient's condition, nurses' clinical experience, type of CCU, 'cry-wolf' phenomenon and nurse/patient ratio). Conclusions: To reduce false alarms, nurses need further postgraduate training, training on monitors and customizing alarms to fit the patient's health status. The complex process of deciding to respond to an alarm includes environmental, professional variables and patient status. Implications for Nursing Management: Nurse managers should ensure that nurses have sufficient experience and training in the CCU, improve the nurse/patient ratio, promote teamwork and ensure that the devices are the latest generation.