A patient who is intoxicated has mydriasis. Which substance could he have been using?

• A. Sedatives
• B. PCP
• C. Opioids
• D. Cocaine

Answer: (D)

Pupillary dilation occurs with heightened sympathetic activity or reduced parasympathetic input. In intoxication, substances that boost sympathetic signaling commonly cause mydriasis. Cocaine blocks the reuptake of norepinephrine and dopamine, amplifying sympathetic nerve activity. This leads to dilated pupils along with signs like tachycardia, hypertension, agitation, and sweating. The other options usually don't produce dilation: sedatives and opioids tend to cause constricted pupils, and while PCP can cause various effects, the classic pupil finding is not as consistent as with cocaine. So the presence of mydriasis in this intoxicated patient most strongly suggests cocaine use.