As much as the ideal treatment goal for severe mental illnesses such as bipolar disorder and schizophrenia is to prevent or delay the recurrence or relapse of acute episodes, when the patient presents with an acute episode, the goal should be to manage behavioural symptoms, and return to prior levels of symptomatic control. In a serious mental illness, the management of the acutely agitated state may require rapid tranquillisation (RT) to control violent and/or disturbed behaviour when all other methods of de-escalation have failed. Current clinical practice guidelines for emergency interventions in the case of acutely disturbed behaviours favour calming the patient by reducing agitation with mild sedation, but not sleep, to allow continued interaction with the patient, to ensure an accurate diagnosis, and to enable patients to be actively engaged in treatment decisions. Pharmacotherapy is an essential element in RT and the available agents used may be unique and separate from the patient's regular course of treatment, primarily because agents used in RT may not be suitable for long-term treatment due to an unfavourable efficacy and safety profile. Therefore, the choice of pharmacotherapy is essential to achieve an effective RT and a smooth transition to standard care and routine daily life for the patient. Of the available agents for RT, aripiprazole demonstrated a favourable efficacy and safety profile both over the short-term - including in its intramuscular form (IM) - and in the long-term treatment of bipolar I disorder and schizophrenia. The objective of this article is to assess the available clinical data on IM aripiprazole as a treatment option for the rapid control of agitation and disturbed behaviours in these conditions and to provide a consensus statement based on the expertise of UK healthcare practitioners in acute treatment units.