Local anesthetics work by reversibly blocking sodium channels and inhibiting nerve impulse conduction. They are classified as esters or amides and include drugs like lidocaine, bupivacaine, and procaine. Amides are metabolized in the liver while esters are metabolized by plasma cholinesterase. Adverse effects include CNS effects like dizziness and cardiovascular effects like hypotension resulting from high systemic levels. Local anesthetics provide benefits of conscious sedation during surgery but risks include potential systemic toxicity if inadvertently injected intravenously or an overdose is given.