Symptoms and Signs of Cyanide Poisoning

Medical Author:
Medically Reviewed on 9/23/2021

Doctor's Notes on Cyanide Poisoning

Cyanide is a potentially deadly poison that makes the human body's cells unable to use oxygen. Call 911 and poison control. Signs and symptoms include

These symptoms and signs may be difficult to relate to the poison. Chronic cyanide poisoning can occur over long time periods with a 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, and 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 U.S. 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.

What Are the Treatments for Cyanide Poisoning?

Treatment of cyanide poisoning is often a medical emergency. The patient should be isolated from the source. An antidote needs to be administered quickly if suspected due to the rapid action of cyanide. Do not wait for laboratory confirmation. Antidotes are administered intravenously usually in a hospital ICU by medical caregivers. The antidotes are as follows:

Medical professionals will perform other treatments like administering supplemental oxygen and continuous cardiac monitoring. If symptoms are severe, intubation may be required. Note that symptoms may be delayed for several hours post-exposure, so most will need a 24-hour observation. The observation period often includes evaluating the following;

  • Respiratory symptoms, especially oxygenation
  • Cardiac symptoms
  • Hemodynamic instability
  • Cerebral edema
  • Serum chemistries, especially lactate
  • Blood gases

Reevaluate the patient about 7-10 days after the hospital discharge to evaluate for neuropsychiatric symptoms (a Parkinson-like syndrome).

Must Read Articles:


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