Final answer:
The action that might be taken against a registered nurse's nursing license if they are convicted of stealing narcotics is a temporary suspension.
Step-by-step explanation:
When a registered nurse is convicted of stealing narcotics from the medical-surgical unit, the action that might be taken against their nursing license is a temporary suspension. Stealing narcotics is a serious violation of ethical and legal standards, and it poses a significant risk to patient safety. The nursing board will typically launch an investigation into the nurse's conduct and may temporarily suspend their license during the investigation.