Cyanide toxicity. Agency for Toxic Substances and Disease Registry

Cyanide is one of the most rapidly acting poisons. Cyanide poisoning is a hazard that may accompany enclosed-space fires, and its occurrence in persons with smoke-inhalation injuries may be underestimated. Acute cyanide exposure primarily causes central nervous system, cardiovascular and respiratory effects. Thyroid function abnormalities have been noted in persons chronically exposed to cyanide. Initial symptoms may be nonspecific. Death may occur in seconds after acute inhalation of hydrogen cyanide.