Abstract
Sulfhemoglobinemia (SulfHb) is a rare condition characterized by the presence of sulfhemoglobin in the blood, resulting from the incorporation of a sulfur atom into the hemoglobin molecule. This alteration prevents hemoglobin from effectively binding and transporting oxygen, leading to clinical symptoms such as cyanosis and tissue hypoxia. We report the case of a 59-year-old female patient who was admitted to the emergency department for desaturation. The patient presented with persistent lip cyanosis and exertional dyspnea over several months. Blood analyses revealed leukocytosis and the detection of sulfhemoglobin. A diagnosis of SulfHb induced by metoclopramide intoxication was established. The treatment involved discontinuing metoclopramide and administering oxygen. The patient was subsequently monitored monthly during outpatient consultations, and the sulfhemoglobin levels were no longer detectable three months after discharge. This case highlights the synergy between metoclopramide overdose, CYP2D6 inhibition by duloxetine, and exposure to sulfur donors in promoting sulfhemoglobin formation. It underscores the importance of a systematic medication review and the early use of co-oximetry in any unexplained desaturation to avoid diagnostic and management delays. The case underscores the importance of vigilance in prescribing and monitoring pharmacological treatments. Rapid recognition of SulfHb and the utilization of appropriate diagnostic tools are essential to ensure optimal patient care.