BACKGROUND Medication safety is an integral dimension of patient safety and one of the 11 principles in the World Health Organization Patient Safety Curriculum Guide. Medication errors can occur by all members of the health care provider; however, they are prevalent in nurses and nursing students. This study aimed to explore and describe medication errors from the perspective of Iranian internship nursing students and faculty. METHODS The present study was done in 2023 using a descriptive qualitative method. Seventeen internship nursing students and five faculty were selected using a purposeful sampling method. Data were collected through in-depth, semi-structured interviews. We used qualitative content analysis for data analysis. RESULTS Data analysis revealed three categories, namely, determinants of error, disclosing/conceal, and psychological consequences of the error, and 12 subcategories. CONCLUSIONS Inadequate medication knowledge and students' inattention to the principles of medication administration have paved the ground for medication errors by internship nursing students, thus threatening patient safety. Effective clinical supervision and training by instructors experienced in teaching and clinical practice can help address this challenge. Reassuring the students and creating a safe and anonymous reporting climate encourages students to report errors.