Acute cyanide poisoning - First aid and medical support

Last updated: 22 November 2024

This information is to assist in recognising symptoms of cyanide poisoning, and for the provision of timely and appropriate first aid and medical support. It applies to the transport, transfer, storage and use of cyanide on a mine site.

Health effects: Hydrogen cyanide (HCN) is a highly toxic and fast acting gas that is released from sodium cyanide solutions used in gold processing. At higher concentrations it may cause death rapidly. Debilitating, yet milder, symptoms may occur at much lower concentrations (10 - 30ppm). The regulated workplace exposure standard is currently a peak limitation of 10ppm (Safe Work Australia, April 2020 (Guide for preventing and responding to cyanide poisoning in the workplace). Cyanide gas concentrations above 50ppm are considered to be immediately dangerous to life and health (IDLH) (Centre for Disease Control, 1994. Hydrogen cyanide. Immediately Dangerous to Life or Health).

Early signs and mild symptoms may occur within minutes of exposure to HCN that include:

  • headache  
  • dizziness
  • feeling faint
  • weakness    
  • fatigue
  • shortness of breath
  • rapid heart rate
  • nausea and vomiting. 

Generally, milder symptoms resolve after cessation of exposure without any permanent damage. Symptoms may be delayed if there is skin contact with cyanide gas or solution, as cyanide uptake from skin absorption occurs at a slower rate than inhalation. Also, skin or mucosal contact with cyanide solutions can cause itching, discolouration and corrosion due to the alkalinity.

Inhalation of high concentrations of HCN gas or ingestion of cyanide salts or solutions may lead to low blood pressure, rapid collapse and loss of consciousness, convulsions, cardiac arrest and death. 

Emergency response planning