Internet-Acquired Sodium Nitrite as an Emerging Suicide Method: Clinical Presentation and Management of Profound Methemoglobinemia

Abstract

Sodium nitrite (NaNO2), an industrial food preservative, has emerged as an accessible means for suicide with increasing online availability. This compound induces methemoglobinemia by oxidising haemoglobin, impairing oxygen transport and causing potentially fatal tissue hypoxia. We report the case of a 30-year-old male who presented to the emergency department after intentionally ingesting approximately 5000 mg of sodium nitrite purchased online. The patient arrived in a confused state, exhibiting severe cyanosis, tachypnoea, and a blood oxygen saturation of 40%. Laboratory analysis revealed a methaemoglobin level of 58%. Despite diagnostic limitations and treatment delays, the patient was successfully treated with two doses of intravenous methylene blue (1 mg/kg), resulting in complete normalisation of methaemoglobin levels within 24 hours. This case highlights critical challenges in managing sodium nitrite poisoning, including misleading standard pulse oximetry readings and the importance of recognising clinical indicators such as “chocolate brown” blood. Despite significant methemoglobinemia (58%), the successful treatment outcome underscores the efficacy of methylene blue therapy when administered promptly. The increasing accessibility of sodium nitrite online poses a significant public health concern. Healthcare providers should maintain a high level of suspicion for methemoglobinemia in patients presenting with unexplained cyanosis resistant to oxygen therapy, prioritise cooximetry for accurate diagnosis, and ensure the immediate availability of methylene blue. This case emphasises the need for improved regulation of industrial chemicals with lethal potential and enhanced mental health interventions.

Keywords

• methemoglobinemia
• sodium nitrite
• methylene blue
• cyanosis; hypoxia

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