Which clinical observation would help differentiate between cocaine intoxication and anxiety disorder?

Pupil size is a critical clinical observation that can help differentiate between cocaine intoxication and anxiety disorder. Cocaine, as a stimulant, typically causes mydriasis (dilated pupils) due to its effects on the autonomic nervous system. In contrast, during an anxiety attack, pupil size may not necessarily change in the same way and can even remain normal.

This distinction is important because it provides healthcare providers with a quick and observable factor that can inform diagnosis and subsequent management of the patient. For instance, a patient exhibiting dilated pupils, in conjunction with other signs of stimulant use, would suggest cocaine intoxication rather than simply an anxiety disorder.

In contrast, while sweating, heart rate changes, and dysphoria can occur in both conditions, they are less reliable for making a definitive differentiation. Sweating can be a common symptom in both anxiety and cocaine intoxication, heart rate can increase in response to both states, and dysphoria, while potentially more pronounced in cocaine withdrawal, is not specific enough to distinguish the two conditions effectively.