Dental procedures are usually performed under local anesthesia, with undergoing complications, like over dosage, toxicity, hypersensitivity and anaphylaxis. The allergic risk involves any of the maneuvers performed during an intervention in the dental medicine cabinet. There are differences between the real allergic reactions and pseudo allergy, differences between groups of local anesthetics, and a need for more knowledge about the additional substances that add supplemental risk (sulfates, latex). Three aspects are to be clarified: how to recognize the patients with real risk, how to prevent the reaction and most important, how to react and treat. Thus, it becomes essential to shed some light on the notions of allergy risk and real allergy risk in the cabinet, with a description of the allergens, of the clinical and laboratory diagnosis methods, as well as of the prevention and treatment measures that can be adopted in case of an allergic incident.