Which local anesthetic is most likely to cause allergic reactions?

Bupivacaine is most likely to cause allergic reactions due to its chemical structure and the potential for the presence of preservatives or additives that may provoke allergic responses in susceptible individuals. Although true allergic reactions to local anesthetics are relatively rare, amide-type anesthetics, such as bupivacaine, can sometimes elicit hypersensitivity reactions in some patients.

In contrast, lidocaine, prilocaine, and articaine are also amides and are generally well tolerated. Allergic reactions to these anesthetics are uncommon and often associated with specific formulations or additional components rather than the anesthetic agent itself. Additionally, the incidence of allergic reactions is higher with ester-type local anesthetics, but among the commonly used amide local anesthetics, bupivacaine is noted for its potential to elicit allergic responses more frequently than the others listed.