Which question is most critical for the nurse to ask a client hearing voices that urge self-harm?

The most critical question for a nurse to ask a client who is hearing voices that urge self-harm focuses on assessing the immediate risk of harm to the client. This question directly addresses the client's safety and is essential for determining whether urgent intervention is needed. If the client is contemplating self-harm or has a plan to carry it out, timely information can inform crisis intervention strategies, including potential hospitalization or therapy adjustments.

Engaging in conversations that only explore when the voices occur, how long they have been present, or the reasons for their return, while potentially informative, do not provide the immediate information necessary to ensure the client's safety. The priority in situations involving self-harm is to ascertain whether there’s an active risk, making the question regarding self-harm the most pertinent in this scenario.