Increasing research has been conducted on individuals presenting with self-harm at emergency departments (EDs). However, less is known about individuals presenting to EDs with only self-harm ideation. We aimed to describe the characteristics of those attending Irish hospitals with self-harm ideation and investigate any differences in comparison to those presenting with suicide ideation. A prospective cohort study was conducted on Irish ED presentations due to suicidal and self-harm ideation. Data were obtained from the service improvement data set of a dedicated nurse-led National Clinical programme for the assessment of those presenting to Irish emergency departments due to Self-harm and Suicide-related Ideation (NCPSHI). A total of 10 602 anonymized presentation data were analysed from 1 January 2018 to 31 December 2019. Descriptive analysis was conducted to compare those with suicidal and self-harm ideation on sociodemographic and care interventions. Being female and aged <29 were more prevalent among the self-harm ideation presentations. Compared to the self-harm ideation group, a higher proportion of those with suicidal thoughts received an emergency care plan (63% vs 58%, p = 0.002) and General Practitioner letter sent within 24 h of presentation (75% vs 69%, p = 0.045). Little variation was found between hospitals for self-harm ideation in both years. Our study suggests that females and younger populations are more prevalent in hospital presentations due self-harm ideation, while presentations related to suicidal ideation are more often made by males and involving substance use. Attention should be given to the relationship between clinicians' attitudes towards care provision and the content of suicide-related ideation ED disclosure.