Written by and the CAM-Cancer Consortium.
Updated January 1, 1970

Is it safe ?

Adverse events

Cyanide is believed to be the active cancer-killing ingredient in Laetrile, which has caused concern over toxicity. Adverse events linked with Laetrile treatment are like the symptoms of cyanide poisoning. These symptoms include: nausea and vomiting, headache, dizziness, bluish discolouration of the skin due to lack of oxygen in the blood, liver damage, abnormally low blood pressure, difficulty walking, droopy eyelids, fever and mental confusion, coma and death. Several deaths have been attributed to Laetrile17,18. If taking Laetrile orally, the potential risk of cyanide poisoning symptoms are increased if any from the list of foods containing Laetrile are eaten (see above) or high doses of vitamin C are taken19. A recent adverse drug reaction case of severe life-threatening accidental cyanide poisoning has been reported in Australia. The report suggests a patient increased her risk of cyanide toxicity by co-ingesting amygdalin with a megadose of Vitamin C (4800mg)20. More severe adverse events (i.e. cyanide poisoning) are seen when Laetrile is administered orally than when it is given by injection, as intestinal bacteria contain enzymes that promote the release of cyanide in the digestive system21.

A review concluded that the risk of people developing cyanide poisoning who ingest Laetrile is high6.


In addition to the above serious concerns, for those with liver problems/damage Laetrile may compromise liver function18. Furthermore, this treatment should be avoided by pregnant or breast-feeding women.


Ascorbic acid (vitamin C) may increase the toxicity of Laetrile/Amygdalin/B1719.


, CAM-Cancer Consortium. [online document]. http://www.cam-cancer.org. January 1, 1970.

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