If a patient is diagnosed with contact dermatitis after using a sunscreen containing PABA, which substance should be avoided?

The correct choice focuses on the relationship between PABA (para-amino benzoic acid) and benzocaine. Benzocaine is an ester local anesthetic structurally similar to PABA. Patients with a sensitivity to PABA may also react to benzocaine, which could trigger or exacerbate contact dermatitis. Therefore, avoiding benzocaine in a patient with a known sensitivity to PABA is prudent to prevent any adverse dermatological reactions.

In contrast, lidocaine, articaine, and mepivacaine are amide local anesthetics that do not share the same chemical structure or potential cross-reactivity with PABA or its derivatives. This makes them safer options in this situation, as they are less likely to provoke similar allergic reactions or contribute to the patient's dermatitis.

Overall, the rationale for avoiding benzocaine is based on its molecular similarity to PABA, which could lead to a higher risk of allergic or irritant responses in individuals sensitized to PABA-containing products.