Background. The likelihood of suicidal behaviour is elevated amongst people with psychosis or bipolar disorder. This study aimed to understand how carers experience supporting family members with psychosis or bipolar disorder who have also experienced suicidal behaviour. Methods. A qualitative thematic analysis of online peer forum posts was carried out on the Relatives Education and Coping Toolkit (REACT) website, an online intervention for carers of people with psychosis and bipolar disorder. Analysis was based on 178 posts by 29 forum users. Posts were selected based on their relevance to suicidal behaviour. Results. Three themes were generated. “Suicide as the ultimate threat” highlights fears emerging from carers’ difficulties with understanding and managing suicidal behaviour. “Bouncing from one crisis to another” reflects carers’ experiences of recurring crises and the challenges of relying on emergency healthcare support. “It definitely needs to be easier to get help” emphasises carers’ desires to be acknowledged by healthcare professionals and included in support offered to service users. Conclusions. Digital platforms, including online forums, brief interventions such as safety planning, and interagency crisis models, hold the potential to meet carers’ needs in this context. However, further research is required to investigate the effectiveness and implementation of these approaches.