Intravenous Hydroxocobalamin for Cyanide Poisoning From Smoke Inhalation: A Comprehensive Scoping Review

Smoke inhalation from closed-space fire can result in hydrogen cyanide (HCN) exposure, an underrecognized contributor to morbidity and mortality in burn and smoke inhalation victims. Hydroxocobalamin, a vitamin B12 precursor, is recommended by the American Heart Association for suspected HCN poisoning; however, evidence regarding its real-world use, particularly in the prehospital setting, remains fragmented. This scoping review aims to identify the existing literature on hydroxocobalamin administration for HCN toxicity secondary to smoke inhalation. BIOSIS Previews, Embase, PubMed, and MEDLINE were searched from inception through January 1, 2025. Data extracted included patient demographic characteristics, hydroxocobalamin dosing, pretreatment and posttreatment clinical data, and adverse events (AEs). We reported descriptive statistics. Of 591 titles and abstracts screened for eligibility, 34 full-text papers were reviewed, and 21 papers describing 512 unique patients were included. Hydroxocobalamin was administered in the prehospital setting in 235 (45.9%) of patients. Most patients received either 5 or 10 g total doses. Pretreatment HCN and blood lactate levels were described in 6 and 12 studies, respectively. Expected AEs included chromaturia and skin discoloration; acute kidney injury was also reported. Among 482 patients with known survival status, 318 (66.0%) survived to hospital discharge. Collectively, these results suggest that hydroxocobalamin was generally well-tolerated and associated with favorable patient outcomes, but evidence remains observational and heterogeneous. This review underscores critical gaps and highlights variability in the real-world use of hydroxocobalamin for HCN toxicity. Additional work is needed to further understand and address barriers to hydroxocobalamin use.