OBJECTIVE: Although previous studies largely emphasize the positive effects of patient participation in patient safety, negative effects have also been observed. This study focuses on bringing together the separate negative effects that have been previously reported in the literature. This study set out to uncover how these negative effects manifest themselves in practice within an obstetrics department. DESIGN: An exploratory qualitative interview study with 16 in-depth semistructured interviews. The information contained in the interviews was deductively analysed. SETTING: The study was conducted in one tertiary academic healthcare centre in the Netherlands. PARTICIPANTS: Patients (N=8) and professionals (N=8) from an obstetrics department. RESULTS: The results of this study indicate that patient participation in patient safety comes in five different forms. Linked to these different forms, four negative effects of patient participation in patient safety were identified. These can be summarised as follows: patients' confidence decreases, the patient-professional relationship can be negatively affected, more responsibility can be demanded of the patient than they wish to accept and the professional has to spend additional time on a patient. CONCLUSION: This study identifies and brings together four negative effects of patient participation in patient safety that have previously been individually identified elsewhere. In our interviews, there was a consensus among patients and professionals on five different forms of participation that would allow patients to positively participate in patient safety. Further studies should investigate ways to prevent and to mitigate the potential negative effects of patient participation.