Which substance commonly causes allergic reactions to ester local anesthetics?

Which substance commonly causes allergic reactions to ester local anesthetics?

• A. Lidocaine
• B. Epinephrine
• C. PABA
• D. Benzocaine

Answer: (C)

Allergic reactions to ester local anesthetics are most commonly linked to para-aminobenzoic acid, PABA. Esters are hydrolyzed in the body to PABA, and in some individuals PABA can act as a sensitizing agent, triggering hypersensitivity reactions. Because of this, the presence of PABA is the classic culprit behind true allergies to ester local anesthetics. In contrast, many amide local anesthetics (like lidocaine) do not produce PABA, and epinephrine is a vasoconstrictor added to mixtures rather than an allergen. While benzocaine is itself an ester, the well-known allergenic association with ester anesthetics centers on PABA rather than the ester drug itself.

Allergic reactions to ester local anesthetics are most commonly linked to para-aminobenzoic acid, PABA. Esters are hydrolyzed in the body to PABA, and in some individuals PABA can act as a sensitizing agent, triggering hypersensitivity reactions. Because of this, the presence of PABA is the classic culprit behind true allergies to ester local anesthetics. In contrast, many amide local anesthetics (like lidocaine) do not produce PABA, and epinephrine is a vasoconstrictor added to mixtures rather than an allergen. While benzocaine is itself an ester, the well-known allergenic association with ester anesthetics centers on PABA rather than the ester drug itself.