Which local anesthetic is less likely to cause allergic reactions?

Amide local anesthetics are less likely to cause allergic reactions primarily due to their chemical structure. Unlike ester local anesthetics, which are metabolized in the body to para-aminobenzoic acid (PABA), a compound that can trigger allergic responses in some individuals, amide anesthetics do not produce PABA as a metabolite.

Amide local anesthetics, such as lidocaine and bupivacaine, are metabolized more slowly in the liver, and their allergy potential is much lower. This makes them a safer option for patients who may have a history of allergies to local anesthetics. While allergic reactions can still occur with amide anesthetics, these incidents are rare compared to esters.

In contrast, esters are known for their higher incidence of allergic reactions, and cocaine is classified as an ester as well, which contributes to its potential for allergic responses. Procaine, also an ester, carries similar risks associated with allergic reactions due to its breakdown products. Therefore, in the context of minimizing the risk of allergic reactions, amide local anesthetics are the preferred choice.