A client arrives in the emergency department with confusion, restlessness, and increased muscle spasms after taking cyclobenzaprine previously. What is the most likely explanation?

• A. The client stopped taking cyclobenzaprine abruptly.
• B. The medication caused tolerance and required a higher dose.
• C. The symptoms indicate an infection.
• D. The patient is experiencing an allergic reaction.

Answer: (C)

Acute confusion with restlessness in the emergency setting is most consistent with delirium, and infection is a common trigger for delirium in adults. While cyclobenzaprine can cause CNS effects and anticholinergic symptoms, sudden changes in mental status accompanied by agitation point toward delirium due to an underlying infection (such as urinary tract infection or pneumonia) rather than a simple drug withdrawal, tolerance, or an allergic reaction. The approach is to assess for infection and other delirium precipitants, monitor vitals, obtain relevant labs and imaging as indicated, treat the infection, and ensure patient safety.