Signs and symptoms of acute cyanide poisoning are not well characterized due to its rare occurrence. Commonly mentioned characteristics of bitter almond odor and cherry red skin have poor clinical utility.
Recently published review of 65 articles (102 patients) showed that most patients experienced following signs and symptoms:
Unresponsive: 78%
Respiratory failure: 73%
Hypotension: 54%
Cardiac arrest: 20%
Seizure: 20%
Cyanosis: 15%
Odor: 15%
Cherry red skin: 11%
There is no clear toxidrome for cyanide poisoning.
In a poisoned patient, health care providers should consider cyanide in their differential diagnosis in the presence of severe metabolic and lactic acidosis (lactic acid > 8 in isolated cyanide poisoning or > 10 in smoke/fire victim).
References
Parker-Cote JL et al. Challenges in the diagnosis of acute cyanide poisoning. Clin Toxicol 2018 Feb 8:1-9. doi: 10.1080/15563650.2018.1435886. [Epub ahead of print]
