Background: It is reported that hospitalised adults require daily oral care to prevent respiratory infections and maintain oral health but patient oral health declines in hospital. Enhancing knowledge and attitudes has not proven effective for changing behaviours or improving oral health. Reports suggest that some nurses find providing oral care unpleasant, therefore, emotions may influence care provision. Aim: To understand how nurses’ and student nurses’ emotional experiences and reactions influence the provision of oral care for hospitalised adult patients. Methods: The initial study explored emotional experiences, reactions and oral care practices. Eight focus groups and ten one-to-one semi-structured interviews with 48 subjects were used to collect data. These were analysed with Grounded Theory. A second study developed and tested methods to measure student nurses’ emotions towards oral care. This used a self-report questionnaire, interviews and Stroop tests. In the final study, 248 student nurses completed a revised self-report questionnaire, a disgust sensitivity questionnaire and two oral care attitude measures; 41 participants additionally completed emotional Stroop tests, implicit association tests and interviews. Qualitative data were analysed with thematic analysis. Χ2 tests, correlations, and Principal Component Analysis were used to analyse quantitative data. Results: Nurses and student nurses experience emotions towards the social, moral and physical aspects of providing oral care; emotions vary with different situations. Unclean mouths are associated with unpleasantness. Failure to provide oral care evokes moral disgust and anxiety. Providing oral care can evoke anxiety and disgust in unpleasant situations, this leads to student nurses reporting altering oral care procedures. Conclusions: Nurses’ and student nurses’ emotions of disgust and anxiety influence oral care. Although these emotions can motivate nurses to provide care, anxiety and disgust can lead to the selection of procedures that avoid aspects of oral care thus reducing the quality of care provided. Nurses’ oral care training programmes need to address these emotions to improve the quality of oral care for patients in hospitals.