Symptoms and Signs of Cyanide Poisoning

Medical Author:
Medically Reviewed on 3/11/2019

Doctor's Notes on Cyanide Poisoning

Cyanide is a potentially deadly poison that makes the human body’s cells unable to use oxygen. Signs and symptoms may be difficult to relate to the poison; for example, weakness, confusion, unusual behavior, shortness of breath, sleepiness, headache, vomiting, abdominal pain, abnormal heartbeats, coma, seizures and death. Chronic cyanide poisoning can occur over a long time periods with gradual onset of symptoms and signs. Acute cyanide poisoning has a rapid onset of almost immediate sudden collapse and may exhibit seizures and a coma before death. Other subtle signs are an unusual pink or cherry-red coloration of the skin and the breath may smell like bitter almonds.

Accidental or intentional exposure to cyanide or compounds that contain cyanide is the cause of cyanide poisoning. Accidental exposures to the poison include fires, especially those that burn rubber, plastic and silk - they can produce cyanide fumes. Industrial exposures to cyanide occur in chemical research labs, photography labs, plastic, fiber and metal processing plants. Potassium cyanide is used in metal extraction plants and to make chemicals such as insecticides. Cigarette smoke is the most common source of cyanide exposure for most people. Some plants, especially seed pits from plants like apricot, bitter almonds, peaches, pears and apples, contain cyanide containing glycosides that can cause poisoning if the seed pits are ingested in large amounts. Laetrile, a cancer treating drug from Mexico not approved for use by the FDA, has the side effect of potential cyanide poisoning. Although most chemicals like solvents, plastics and others containing cyanide compounds have been taken off the market, some may still be available.

Intentional exposure to cyanide usually happens when a person wants to commit suicide or wants to harm or kill someone. Intentional exposures to cyanide-containing pills or tablets can cause a rapid and painful death. However, small amounts of cyanide placed in foods also can be deadly over time.

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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.