When Pain Relief Turns Perilous: Uncovering the Hidden Dangers and Advanced Management of Benzocaine-Induced Methemoglobinemia.

Benzocaine-induced methemoglobinemia is a rare complication associated with benzocaine, a local anesthetic known for its rapid pain relief. Acquired methemoglobinemia occurs when hemoglobin is oxidized to a ferric state, impairing oxygen binding. This condition can lead to respiratory distress and potentially fatal outcomes if not promptly diagnosed and treated. We present the case of a 61-year-old Caucasian female admitted with respiratory distress after lumbar stenosis surgery. She developed acute hypoxemic respiratory failure due to pneumonia. Although initially responsive to antibiotics and oxygen, her condition worsened overnight despite non-invasive bilevel-positive airway pressure (BiPAP) therapy. The use of benzocaine spray for throat pain led to suspected methemoglobinemia. She was treated with high-dose vitamin C and methylene blue, resulting in significant improvement. This case report aims to raise awareness among healthcare workers and emphasizes that timely recognition and management are crucial for better outcomes.