Which of the following is a symptom of lidocaine toxicity?

A metallic taste is a recognized symptom of lidocaine toxicity. This sensation occurs due to central nervous system involvement when lidocaine reaches toxic levels, affecting the neurons responsible for taste perception. As lidocaine is a local anesthetic, overdose can lead to increased plasma concentrations that might cross the blood-brain barrier, prompting neurological side effects, including the metallic taste.

Visual impairment and hypotension are also potential outcomes of lidocaine toxicity but are more indicative of advanced or severe toxicity, often accompanied by other systemic effects rather than being characteristic early signs. Hemolytic anemia does not typically relate to lidocaine toxicity, as it is associated with other conditions or drug reactions that do not involve lidocaine's anesthetic mechanisms.