How does topical anesthesia work on the nose or throat?

Topical anesthesia, also known as surface anesthesia, is a method of administering local anesthetics directly to mucous membranes, such as those found in the nose and throat.1

These anesthetics work by temporarily blocking the conduction of nerve impulses along sensory nerve fibers, which prevents the transmission of pain signals to the brain. At a molecular level, the anesthetic drug penetrates the fatty membrane of the nerve fibers. Once inside, it blocks the ion channels that allow sodium ions to flow during nerve excitation. By preventing this influx of sodium, the anesthetic stops the electrical currents necessary to propagate a nerve impulse, effectively inducing a localized loss of sensation.1

Because these fibers are thin and highly susceptible to the drug, pain sensation is typically the first to be blocked, providing relief for conditions like a sore throat or facilitating minor medical procedures in these regions.1