Do true allergic reactions to local anesthetics exist?

Yes, but they are very uncommon. Usually, these reactions are seen with the ester anesthetics. These patients are either allergic to the paraben preservatives found in these preparations or to the ester metabolite, PABA. Parabens are known to cross react with PABA. Lidocaine is an excellent substitute in cases of true ester anesthetic allergy, as no cross-reactivity exists between the amide and ester groups of anesthetics. True allergic reactions to lidocaine are extremely rare. Most of the so-called allergic reactions to lidocaine are, in fact, due to vasovagal syncope or, less commonly, epinephrine side effects. However, patients may be allergic to the parabens and sodium metabisulfite preservatives. Preservative-free lidocaine is available.