BMJ Case Reports 2017; doi:10.1136/bcr-2017-220814
  • Reminder of important clinical lesson

An unusual presentation of chronic cyanide toxicity from self-prescribed apricot kernel extract

Press Release
  1. Joel Smith
  1. Departments of Anaesthesia and Perioperative Medicine, Alfred Hospital, Melbourne, Victoria, Australia
  1. Correspondence to Dr Alex Konstantatos, a.konstantatos{at}
  • Accepted 6 July 2017
  • Published 11 September 2017


Hypoxia under general anaesthesia is a potentially life-threatening condition. A seemingly well 67-year-old man appeared hypoxic with peripheral pulse oximetric measurement during routine anaesthesia. Postoperatively, the patient admitted to daily self-prescription of apricot kernel extract for a period of 5 years. Apricot kernel is a commonly taken extract used for a range of ailments, and is associated with cyanide toxicity, which was confirmed through blood analysis. Our explanation for the hypoxic measurement was the presence of free cyanide interfering with functioning of the peripheral pulse oximeter. On cessation of the apricot kernel extract, peripheral oxygen saturations returned to normal. Cardiac and respiratory causes together with rare haemoglobinopathies were excluded. This case illustrates how chronic dosing of complementary medicines can result in harmful toxicities, which may carry potential for serious consequences and how these chronic toxicities may present to physicians in atypical ways.


  • Contributors AK initially managed and consented the patient. MSK investigated the biomedical equipment. AK, MSK, AB and JS conducted and interpreted further testing with patient and helped prepare the manuscript.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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