What sign indicates that the patient has been abusing amphetamines?

Increased blood pressure is a common sign of amphetamine abuse. Amphetamines are stimulants that cause an increase in sympathetic nervous system activity. This can lead to elevated heart rate and higher blood pressure as the body's fight-or-flight response is activated. Individuals using these substances often experience heightened energy levels and increased physical activity, which can further contribute to cardiovascular changes including hypertension.

While other signs such as auditory hallucinations can occur in cases of severe intoxication or withdrawal, increased blood pressure is a more consistent and immediate physiological response that is directly linked to stimulant use. The other options do not align with the typical effects of amphetamines, which primarily stimulate rather than depress the central nervous system, differentiating them from other substances that may cause fatigue or constricted pupils.