A 66-year-old woman has been acting off for two days after recently starting a new antibiotic four days ago. What is the most appropriate next step?

• A. Discharge home with instructions
• B. Refer to ED
• C. Begin benzodiazepines
• D. Increase fluid intake

Answer: (B)

Acute delirium in an older adult after starting a new antibiotic signals a possible medication-related delirium or another serious medical issue, and it requires urgent evaluation. In the emergency department, clinicians can promptly assess mental status, vital signs, oxygenation, glucose, electrolytes, and organ function, while reviewing all medications to identify the offending agent and rule out causes such as infection, dehydration, or metabolic imbalances. This setting also allows for safe management and monitoring, discontinuation or substitution of the suspected antibiotic if needed, and appropriate treatment and safety measures for delirium. Discharging home would be unsafe because delirium in an elderly patient can mask life-threatening problems and lead to poor outcomes, benzodiazepines are not appropriate here since they can worsen delirium, and simply increasing fluids does not address the underlying cause.