Which anesthetic is contraindicated for patients allergic to para-aminobenzoic acid?

Topical benzocaine is contraindicated for patients allergic to para-aminobenzoic acid (PABA) because benzocaine is an ester-type local anesthetic, and its chemical structure is closely related to PABA. Esters, such as benzocaine, are metabolized in the body to PABA, which can provoke allergic reactions in susceptible individuals. Those who are allergic to PABA should avoid ester local anesthetics to prevent an allergic response.

On the other hand, EMLA (a combination of lidocaine and prilocaine), lidocaine, and prilocaine are amide-type local anesthetics. Amides do not possess the same chemical structure as PABA and are usually well-tolerated by patients with PABA allergies, making them safer alternatives for anesthesia in these cases.