What is cyanide
Last updated: April 1, 2026
Key Facts
- Cyanide binds to iron in mitochondrial cytochrome c oxidase, blocking cellular respiration and ATP energy production
- As little as 50-100 mg of potassium cyanide (approximately the size of a few grains of salt) is lethal to an adult human
- Cyanide has legitimate industrial uses in metal processing, electroplating, photography, pesticide manufacturing, and producing certain plastics
- Chronic low-level cyanide exposure can result from smoking tobacco, as tobacco plants naturally contain trace cyanide compounds
- Cyanide antidotes include hydroxocobalamin and sodium thiosulfate, which work best when administered within minutes of exposure
What is Cyanide?
Cyanide is a toxic chemical compound containing a carbon-nitrogen bond that is lethal to most organisms at very small concentrations. It exists in multiple forms: hydrogen cyanide (a colorless gas with a bitter almond smell), cyanide salts (solid compounds like potassium cyanide and sodium cyanide), and organic cyanide compounds. Cyanide's extreme toxicity and rapid action make it one of the most dangerous poisons known, affecting the body's ability to process oxygen at the cellular level.
How Cyanide Affects the Body
Cyanide prevents cells from using oxygen through a mechanism that disrupts cellular respiration. Specifically, cyanide binds to the iron in cytochrome c oxidase, an enzyme in the mitochondrial electron transport chain responsible for cellular energy production. When this enzyme is inhibited, cells cannot produce ATP (adenosine triphosphate), the energy currency required for all cellular functions. Tissues with the highest metabolic demands—the brain and heart—are affected first. Within minutes of exposure to lethal doses, organ failure and death occur. Victims essentially suffocate at the cellular level despite adequate oxygen in the bloodstream.
Routes of Exposure
Cyanide can enter the body through multiple routes: inhalation of hydrogen cyanide gas, ingestion of cyanide salts or compounds, or dermal absorption through skin contact. Hydrogen cyanide gas is volatile and rapidly absorbed through the lungs, making inhalation exposure particularly dangerous. The lethal dose varies by route and form—ingestion of cyanide salts is extremely dangerous, with fatal doses measured in tens of milligrams. The speed of onset depends on exposure route; inhalation causes symptoms within seconds to minutes, while ingestion symptoms may develop within minutes to hours.
Industrial and Legitimate Uses
Despite its toxicity, cyanide has important industrial and scientific applications. It's used in electroplating to deposit metal coatings, metal processing to extract gold and silver from ores, photography in certain film and printing processes, chemical synthesis for manufacturing plastics and other compounds, pesticide production, and laboratory testing. These industries maintain strict safety protocols and containment procedures to minimize exposure risks.
Natural Sources and Treatment
Cyanide compounds occur naturally in small amounts in many plants including cassava root, apple seeds, peach pits, and bitter almonds—though the concentrations are typically too low to cause harm through normal consumption. Tobacco smoke contains trace levels of cyanide. Medical treatment for acute cyanide poisoning involves antidotes like hydroxocobalamin, which binds cyanide and renders it harmless, or sodium thiosulfate, which converts cyanide to thiocyanate for excretion. These antidotes are most effective when administered within minutes of exposure. Supportive care including oxygen therapy and monitoring are also critical components of treatment.
Related Questions
Where is cyanide found naturally?
Cyanide compounds occur naturally in many plants including cassava root, apple seeds, peach pits, bitter almonds, and cherry pits in amounts too low to cause harm through normal consumption. Tobacco smoke also contains trace levels of cyanide.
What are symptoms of cyanide poisoning?
Acute cyanide poisoning symptoms develop rapidly and include rapid breathing, confusion, loss of consciousness, seizures, cardiac arrhythmias, and cardiovascular collapse. At high doses, death can occur within minutes. Chronic low-level exposure may cause neurological issues.
How is cyanide detected in the body?
Cyanide can be measured in blood samples, but detection is challenging because cyanide is rapidly metabolized and excreted. Forensic testing may include serum cyanide levels, tissue analysis, or examining post-mortem samples for cyanide metabolites.
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Sources
- ATSDR - Cyanide ToxicityCDC/ATSDR
- NIH PubChem - CyanideNIH