Hydrogen Sulfide Toxicity Medication

Updated: Feb 25, 2022
  • Author: David Vearrier, MD, MPH; Chief Editor: Michael A Miller, MD  more...
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Medication Summary

Antidotal treatment of hydrogen sulfide (H2 S) poisoning is based on the creation of methemoglobinemia. Symptomatic treatment includes the use of bronchodilators for patients with bronchospasm.


Cyanide Antidotes

Class Summary

Nitrite administration leads to formation of methemoglobinemia. H2 S has a much greater affinity for methemoglobin than for cellular cytochromes, leading to lower metabolic toxicity.

Sodium thiosulfate & sodium nitrite (Nithiodote)

Although approved for use in cyanide poisoning, sodium nitrite is the initial drug of choice for hydrogen sulfide poisoning. Because high methemoglobin concentrations can cause fatal reduction of oxygenation and perfusion, methemoglobin concentrations should be closely monitored and kept below 30%.

Sodium thiosulfate should not be used in the treatment of hydrogen sulfide poisoning. In the classic cyanide antidote kit, sodium nitrite and sodium thiosulfate are provided. The nitrites cause the formation of methemoglobinemia, scavenging both cyanide and hydrogen sulfide. In cyanide poisoning, sodium thiosulfate enhances the activity of the enzyme rhodanese, a mammalian enzyme that likely evolved in response to the ubiquitous presence of cyanide in nature. Rhodanese catalyzes the transfer of sulfate from sodium thiosulfate to cyanide to form thiocyanate, a less toxic form that is excreted by the kidneys. This does not share the crossover treatment that sodium nitrites do with hydrogen sulfide (ie, it is useless in hydrogen sulfide poisoning).