Pharmacology · single question
A 6-month-old develops cyanosis and shortness of breath after topical benzocaine for teething. Most likely adverse effect?
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Correct answer: A. Acute methemoglobinemia
- A. Correct. Benzocaine is a classic cause of methemoglobinemia — cyanosis unresponsive to oxygen, especially in infants. (FDA warns against use under 2 years.)
- B. Anaphylaxis presents with urticaria/angioedema/hypotension, not isolated cyanosis from altered hemoglobin.
- C. Local necrosis would be a tissue finding, not systemic cyanosis.
- D. CNS depression follows systemic toxicity, but the described cyanosis is characteristic of methemoglobinemia.