Immunological and serological studies of patients with allergy to local anesthetics

Local anesthetics are frequently used in dental treatment. Allergic reactions to local anesthetics are very rare, and reportedly accounts for about 0.6% of all drug-induced adverse reactions. Amide-type local anesthetics, such as lidocaine, which are used in recent years, are estimated to have an even lower incidence of allergic reactions. However, patients who have once had on allergic reaction to a local anesthetic are sometimes concerned about such reactions when visiting a doctor. We interview such patients about the conditions when the local anesthetic was used, the condition of resuscitation, the presence or absence of systemic diseases, history of allergic reactions, familial history, and others. During the past 10 years, nine patients (four males and five females) were finally suspected to have allergies to local anesthetics. Allergic reactions occurred during dental treatment in four patients and during surgical operations in five patients.The type of allergy was I in eight patients and IV in one patient. In the patients with type I allergy, definitive diagnosis by patch test and intradermal reaction test had been performed at other medical institutions. At our department, we performed patch test, drug lymphocyte stimulation test (DLST), intradermal reaction test, and other tests in the nine patients. Based on the results of these tests, challenge tests with lidocaine were done in eight patients, and dental treatment was performed safely. In one patient, type N allergy occurred, and we now have difficulty treating this patient. In the remaining one patient, promethazine hydrochloride was used instead of local anesthetics, and we were able to successfully complete dental treatment because adequate aresthesia was induced.