March 2021

This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the use of laetrile/amygdalin in the treatment of people with cancer. It is intended as a resource to inform and assist clinicians who care for cancer patients. It does not provide formal guidelines or recommendations for making health care decisions.

This summary is reviewed regularly and updated as necessary by the PDQ Integrative, Alternative, and Complementary Therapies Editorial Board, which is editorially independent of the National Cancer Institute (NCI). The summary reflects an independent review of the literature and does not represent a policy statement of NCI or the National Institutes of Health (NIH).

Overview

This cancer information summary provides an overview of the use of laetrile as a treatment for people with cancer. The summary includes a history of laetrile research, a review of laboratory studies, the results of clinical trials, and possible side effects of laetrile use.

This summary contains the following key information:

  • Laetrile is another name for the natural product amygdalin, which is a chemical constituent found in the pits of many fruits and in numerous plants.
  • Hydrogen cyanide is thought to be the main anticancer compound formed from laetrile via in situ release.
  • Laetrile was first used as a cancer treatment in Russia in 1845, and in the United States in the 1920s.
  • Laetrile has shown little anticancer activity in animal studies and no anticancer activity in human clinical trials.
  • The side effects associated with laetrile toxicity mirror the symptoms of cyanide poisoning, including liver damage, difficulty walking (caused by damaged nerves), fever, coma, and death.
  • Laetrile is not approved for use in the United States.
  • Inappropriate advertisement of laetrile as a cancer treatment has resulted in a U.S. Food and Drug Administration investigation that culminated in charges and conviction of one distributor.

Many of the medical and scientific terms used in this summary are hypertext linked (at first use in each section) to the NCI Dictionary of Cancer Terms, which is oriented toward nonexperts. When a linked term is clicked, a definition will appear in a separate window.

Reference citations in some PDQ cancer information summaries may include links to external websites that are operated by individuals or organizations for the purpose of marketing or advocating the use of specific treatments or products. These reference citations are included for informational purposes only. Their inclusion should not be viewed as an endorsement of the content of the websites, or of any treatment or product, by the PDQ Integrative, Alternative, and Complementary Therapies Editorial Board or the National Cancer Institute.