An alarming case of benzocaine-induced methemoglobinemia was reported after a routine medical procedure. An 87-year-old man, recently admitted to hospital with septic shock caused by obstructive pyelonephritis, faced life-threatening complications following the use of a benzocaine spray. Medical staff stabilised the patient and transferred him to general care. They applied a 20% benzocaine spray to numb the nasopharyngeal area, easing the insertion of a nasogastric tube required for feeding due to his ongoing dysphagia and appetite loss.

Hours after the procedure, the man became unresponsive, with his blood oxygen levels dangerously dropping to 85% despite high oxygen therapy. When re-admitted to the intensive care unit, medical staff noticed chocolate-brown arterial blood, a sign of methemoglobinemia. Blood tests revealed his methemoglobin levels exceeded 28%, confirming the life-threatening reaction to the benzocaine spray. Immediate intervention with intravenous methylene blue led to improvements in both his oxygen levels and consciousness.

Risks of Benzocaine-Induced Methemoglobinemia

Benzocaine-induced methemoglobinemia is a recognised but rare complication of benzocaine use. Methemoglobinemia can occur even with routine medical procedures, emphasising the need for heightened awareness among healthcare professionals. The authors stress that early recognition and treatment with methylene blue are critical to reversing the condition and preventing severe outcomes. Source: Critical Care Medicine Journal

The Mayo Clinic warns that benzocaine, commonly used as a topical anaesthetic, may cause a rare but serious blood disorder called methemoglobinemia. This condition can lead to dangerously low oxygen levels in the blood, posing life-threatening risks if not promptly addressed. The clinic advises caution when using benzocaine sprays, particularly in vulnerable populations such as the elderly or those with pre-existing health conditions. Source: Mayo Clinic

A Tragic Reminder for Healthcare Professionals

Despite surviving the acute crisis, the patient sadly died weeks later due to complications of septic shock, further compounded by respiratory failure. This tragic case highlights the risks associated with benzocaine-related oxygen deficiency in procedures once considered low-risk.

Healthcare professionals warn against the casual use of substances in clinical settings without a thorough understanding of their potential dangers. While benzocaine sprays are common for pain relief, cases like this remind us of the critical need to prioritise safety and alternative measures to avoid preventable harm.

Source: Jama Network