Allergy to local anesthetics in dentistry. Myth or reality?

BACKGROUND Local anesthetics are drugs frequently used in dentistry. Although they are usually well-tolerated drugs, sometimes, they can cause adverse reactions of different kinds and severity. True incidence of local anesthetics' allergic reactions is unknown. OBJECTIVES To evaluate the incidence of immediate adverse events in subjects who required local anesthetic injection to receive dental treatment; to assess the incidence of anaphylactic allergic reactions among those recorded as adverse events; to analyze the relationship between these patients' atopic antecedents and documented allergic reactions. MATERIAL AND METHODS A prospective, open-label, non-comparative study including a total of 5,018 subjects who received local anesthetics during dental treatment, despite their age, was carried on in 7 either private or public odontological assistance centers. All the reactions that could appear during the first hour following the anesthetic act were assessed. RESULTS Twenty-five adverse reactions were diagnosed, representing 0.5% of the studied population. None of them was due to an allergic cause. Most of them (22/25) were mild, quickly reversible, psychogenic or vasovagal reactions. One of the cases was related to defects of the anesthetic technique. The remaining two cases, which were initially considered as possibly due to an allergic cause, were discarded after being studied with skin and dose provocative challenge tests with the anesthetic. CONCLUSION The allergic reactions to the local anesthetics are very rare and most of the adverse reactions are psychogenic/vasovagal. These facts should be known by the physician and by the dentist in order to minimize the frequent fears and "myths" about the use of local anesthetics at the dentist office.