Which of the following is a sign of cholinergic overdose?

Constriction of pupils, also known as miosis, is indeed a sign of cholinergic overdose. This occurs due to the overstimulation of the parasympathetic nervous system, which is characteristically affected in such cases. Cholinergic agents, such as acetylcholine or drugs that mimic its action, lead to increased secretions and smooth muscle contraction, which includes constriction of the pupils via the action on the sphincter pupillae muscle.

In contrast, hypertension, tachycardia, and dry mouth are typically associated with adrenergic stimulation rather than cholinergic effects. They arise from the stimulation of the sympathetic nervous system, which results in increased heart rate, elevated blood pressure, and decreased salivation. Therefore, recognizing miosis as a sign of cholinergic overdose is critical for identifying and managing this condition effectively.