apricot seeds toxicology cyanide

What toxin is found in bitter apricot kernels?

  1. Cardiac glycoside
  2. Cyanogenic glycoside
  3. Dinitrophenol
  4. Lysergic Acid

2. Cyanogenic glycoside


Apricot kernels contain a cyanogenic glycoside called amygdalin which is hydrolyzed to hydrogen cyanide in the gastrointestinal tract [1]. There are over 2,000 species of cyanogenic glycoside producing plants, including apricots, almonds, peaches, and cassava [2]. The amount of hydrogen cyanide in each kernel varies and ranges from 540 to 2,000 mg/kg [2]. The lethal dose range reported for cyanide in humans is 0.56-1.5 mg/kg [3]. Grinding or chewing the kernel increases toxicity [4]. The ingestion of approximately 20-30 apricot kernels in adults, and fewer in children, may lead to severe toxicity [2, 3, 5].

Although poisoning by ingestion of cyanogenic foods is much more common in tropical countries, there have been reported cases in the US [1, 3]. Additionally, children appear to develop more toxic effects from cyanogenic foods when compared to adults [1]. Despite described adverse effects in literature and investigation by the US FDA, these products continue to be marketed as natural anticancer agents [2].

How does cyanide produce toxicity? [1,6,7]

  • Cyanide inhibits cellular respiration in all aerobic organisms by blocking cytochrome oxidase.
  • This enzyme functions in the electron transport chain within the mitochondria and plays a key role in the conversion of catabolic products of glucose into ATP.
  • When cytochrome oxidase is inhibited, ATP molecules are not formed.
  • This causes a shift from aerobic to anaerobic cellular respiration and therefore results in lactic acidosis and systemic side effects.

What are the symptoms of cyanide poisoning? [1,6,7]

  • Dizziness, confusion, headache
  • Shortness of breath
  • Weakness and malaise
  • Nausea and vomiting
  • Hypotension, seizures, coma, apnea, arrhythmias
  • Death due to cardiorespiratory arrest

How do you diagnose cyanide poisoning? [7]

  • Diagnosis is based largely upon the history and clinical presentation.
  • Cyanide levels can be obtained for confirmation but do not generally return in a clinically relevant time frame.
  • Laboratory findings suggestive of cyanide poisoning include:
    • Elevated lactate
    • Anion gap metabolic acidosis
    • Reduced arterial to venous oxygen difference as an indicator of reduced oxygen utilization.

How to you treat cyanide poisoning? [1, 5-8]

  • If left untreated, cyanide toxicity can be fatal.
  • Antidotal therapy includes hydroxocobalamin, sodium nitrite, and sodium thiosulfate.
  • PREFERRED: Hydroxocobalamin (more favorable safety profile)
    • Binds to cyanide, forming cyanocobalamin (i.e., vitamin B12)
    • Cyanocobalamin is more easily excreted in the urine or detoxified by rhodanese.
    • Urine discoloration is seen after administration as seen in ALiEM Toxicology Visual Pearl: Discolored Skin and Urine [9].
    • Adult dose: 5 grams IV
    • Pediatric dose: 70 mg/kg IV up to 5 grams
  • ALTERNATIVE: Sodium nitrite
    • Induces methemoglobin, which binds to cyanide to form cyanmethemoglobin, which restores mitochondrial function
    • Nitrite-induced methemoglobinemia can be dangerous and even fatal in those with undiagnosed G6PD deficiency, anemia, and in the pediatric population.
    • When methemoglobin is present, the oxygen carrying capacity of red blood cells is reduced.
    • Dosing for 3% sodium nitrite solution [8]:
      • Adults: 300 mg (10 mL) no faster than 5 mL/min
      • Pediatrics: 6 mg/kg (0.2 mL/kg) up to 10 mL no faster than 5 mL/min
  • Sodium thiosulfate
    • Acts as a sulfur donor, converting cyanide to a less toxic thiocyanate which is subsequently excreted in the urine.
    • May be used alone, or in conjunction with either sodium nitrite or hydroxocobalamin
    • Dosing for 25% solution:
      • Adults: 12.5 grams (50 mL)
      • Pediatrics: 250-412 mg/kg (1-1.65 mL/kg) not to exceed 50 mL or 12.5 grams

Bedside Pearls

  • Ingestion of large quantities of cyanogenic foods can result in cyanide toxicity.
  • Children may be more susceptible than adults to the toxic effect of cyanogenic foods.
  • Standard cyanide antidotes can be used to treat the toxic effects from ingestion of cyanogenic glycosides.
  • Hydroxocobalamin is the preferred antidote for cyanide poisoning.


  1. Geller RJ, Barthold C, Saiers JA, Hall AH. Pediatric cyanide poisoning: causes, manifestations, management, and unmet needs. Pediatrics. 2006 ;118(5):2146-58. PMID: 17079589
  2. Chaouali N, Gana I, Dorra A, Khelifi F, Nouioui A, Masri W, Belwaer I, Ghorbel H, Hedhili A. Potential Toxic Levels of Cyanide in Almonds (Prunus amygdalus), Apricot Kernels (Prunus armeniaca), and Almond Syrup. ISRN Toxicol. 2013 ;2013:610648. PMID: 24171123
  3. Suchard JR, Wallace KL, Gerkin RD. Acute cyanide toxicity caused by apricot kernel ingestion. Ann Emerg Med. 1998 ;32(6):742-4. PMID: 9832674
  4. Tatli M, Eyüpoğlu G, Hocagil H. Acute cyanide poisoning due to apricot kernel ingestion. Journal of Acute Disease. 2017;6(2): 87-88. DOI: 10.12980/jad.6.2017JADWEB-2016-0075.
  5. Cigolini D, Ricci G, Zannoni M, Codogni R, De Luca M, Perfetti P, Rocca G. Hydroxocobalamin treatment of acute cyanide poisoning from apricot kernels. BMJ Case Rep. 2011;2011:bcr0320113932. PMID: 22694886
  6. Borron SW. Recognition and treatment of acute cyanide poisoning. J Emerg Nurs. 2006;32(4 Suppl):S12-S18. PMID: 16860672.
  7. Holstege CP, Kirk MA. Cyanide and Hydrogen Sulfide. In: Nelson LS, Howland M, Lewin NA, Smith SW, Goldfrank LR, Hoffman RS. eds. Goldfrank’s Toxicologic Emergencies, 11e. McGraw Hill; 2019. Accessed August 20, 2023.
  8. Howland M. Nitrites (Amyl and Sodium) and Sodium Thiosulfate. In: Nelson LS, Howland M, Lewin NA, Smith SW, Goldfrank LR, Hoffman RS. eds. Goldfrank’s Toxicologic Emergencies, 11e. McGraw Hill; 2019.
  9. Malashock H. ACMT Toxicology Visual Pearls: Discolored Skin and Urine. (2017, July 10). ACMT Visual Pearls, Tox Medications. Accessed August 20, 2023.
Maureen Nsofor, MD

Maureen Nsofor, MD

Pediatric Emergency Medicine Fellow
Atrium Health’s Carolinas Medical Center
Maureen Nsofor, MD

Latest posts by Maureen Nsofor, MD (see all)

Christine Murphy, MD

Christine Murphy, MD

Associate Professor of Emergency Medicine
Medical Toxicologist
Department of Emergency Medicine
Atrium Health’s Carolinas Medical Center