Objectives We aimed to investigate the characteristics of adolescents with Bipolar disorder-I with irritability and agitation (Mania+IA) compared to those without irritability and agitation (Mania-IA) in a multi-center representative sample. Methods Data of 145 patients from three tertiary-care inpatient units between 2016 and 2021 were obtained. Psychomotor agitation was defined as a score of >= 3 on the YMRS "Increased Motor Activity--Energy" item, irritability as a score of >= 4 on the YMRS 'irritability' item, and severity anchors of speech and thought disturbance on the YMRS '6 and 7' items. Results Previous manic episodes (p = 0.013), involuntary hospitalization (p = 0.006), psychotic features (p = 0.001), formal thought disorder (p = 0.010) and aggressive/disruptive behavior (p = 0.021) were more frequent in the Mania+IA group. Conversely, depressive episodes (p = 0.006) and family history of depression (p = 0.024) were more frequent in the Mania-IA group. The Mania+IA had poorer functioning at the time of discharge. Conclusions Irritability and agitation were closely related to complications, psychotic symptoms and thought disorder. Assessment and monitoring of psychomotor agitation and irritability may help child and adolescent psychiatrists to predict clinical difficulties and appropriate interventions.