Among the early signs of a true allergic reaction (rather than a non-allergic side effect) to local anesthesia, which is the most specific early indicator?

A true allergic/anaphylactic reaction classically begins with skin/mucosal findings — urticaria (hives), pruritus, or flushing — as the earliest, most specific manifestation, before any progression to respiratory or cardiovascular involvement. Diaphoresis, nausea, and lightheadedness are nonspecific autonomic symptoms that also occur with vasovagal syncope or other non-allergic reactions, making them far less specific for a true drug allergy.