The incidence of allergic reactions to local anesthetics is low.p><p id="spar0010">Most cases involve a psychogenic reaction rather than an allergic reaction.p><p id="spar0015">Additives and preservatives added to local anesthetics may cause allergic reactions.p><p id="spar0020">Vascular resorption of epinephrine-containing local anesthetics may produce cardiovascular signs similar to an allergic reaction.p><p id="spar0025">Diagnosis of allergy to local anesthetics must be established by skin testing and provocative challenge.