# Evidence for Hydroxocobalamin in Cyanide Toxicity Caused by Smoke Inhalation: An Updated Systematic Review

## TL;DR

This review examines the use of hydroxocobalamin for cyanide poisoning from smoke inhalation, finding uncertain benefits and potential risks like kidney injury.

## Contribution

An updated systematic review analyzing the safety and efficacy of hydroxocobalamin in smoke inhalation-related cyanide toxicity.

## Key findings

- Mortality rates were similar between hydroxocobalamin and supportive treatment groups.
- Hydroxocobalamin was associated with acute kidney injury in some studies.
- One study suggested a potential link to methemoglobinemia.

## Abstract

Hydroxocobalamin is the first‐line treatment for confirmed cyanide poisoning. Its empiric use in patients with smoke inhalation injury—where cyanide toxicity is often suspected but not confirmed—remains controversial. Further research is needed to fully understand the benefits and risks associated with its use. This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines to provide a systematic review of the use of hydroxocobalamin for the treatment of cyanide poisoning secondary to smoke inhalation injury, with a particular focus on mortality and adverse reactions.

A systematic search of the Cochrane Library, PubMed, and Embase was conducted for studies on cyanide poisoning from smoke inhalation injury treated with hydroxocobalamin. The search was limited to studies from the inception of the journals until July 30, 2025. The quality of the studies was assessed using the Newcastle–Ottawa Scale.

Six studies, comprising a total of 1238 patients, were identified as meeting the inclusion criteria; however, they did not meet the quality threshold for meta‐analysis. Thus, only a systematic review was performed. Two studies reported mortality rates, which were found to be similar between the hydroxocobalamin and supportive treatment groups. In contrast, two studies indicated an association between hydroxocobalamin and acute kidney injury, whereas one study proposed a potential correlation with methemoglobinemia.

In light of the uncertain benefits and potential risks associated with hydroxocobalamin use for cyanide poisoning from smoke inhalation injury, its administration should be approached with caution. Well‐designed randomized controlled trials are urgently needed to establish optimal treatment strategies for this patient population.