Laetrile/Amygdalin (PDQ®)–Patient Version

NOTE: There is either no new research on this topic or the recent published research is weak and not appropriate for inclusion in the summary. Therefore, the information in this summary is no longer being updated and is provided for reference purposes only.

1. What is laetrile (amygdalin)?

   Laetrile is a compound that has been used as a treatment for people with cancer. Laetrile is another name for amygdalin. Amygdalin is a bitter substance found in fruit pits, such as apricots, raw nuts, lima beans, clover, and sorghum. It makes hydrogen cyanide which is changed into cyanide when taken into the body. Hydrogen cyanide is thought to kill cancer cells. Laetrile is also called Vitamin B-17, although it has not been approved as a vitamin by the American Institute of Nutrition Vitamins.

2. How is laetrile given?

   Laetrile is given by mouth (orally) as a pill. It can also be given by injection into a vein (IV) or muscle (intramuscular). Laetrile is commonly given by IV at first, then orally as maintenance therapy (treatment given to help extend the benefit of previous therapy).

   Laetrile treatments are given in Mexico and some U.S. clinics. Sometimes laetrile is given in combination with a metabolic therapy program (special diet, high-dose vitamins, and pancreatic enzymes).

3. Have any laboratory or animal studies been done using laetrile?

   In laboratory studies, tumor cells are used to test a substance to find out if it is likely to have any anticancer effects. In animal studies, tests are done to see if a drug, procedure, or treatment is safe and effective in animals. Laboratory and animal studies are done before a substance is tested in people.

   Laboratory and animal studies have tested the effects of laetrile in laboratory experiments. For information on laboratory and animal studies done using laetrile, see the Laboratory/Animal/Preclinical Studies section of the health professional version of Laetrile/Amygdalin.

4. Have any studies of laetrile been done in people?

   No controlled clinical trials of laetrile have been reported. Anecdotal reports and case reports have not shown laetrile to be an effective treatment for cancer.

   Benzaldehyde, which is made when laetrile is broken down by the body, has been tested for anticancer activity in people. In two clinical series, patients with advanced cancer who had not responded to standard therapy were treated with benzaldehyde. Some patients had a complete response, while some had a decrease in tumor size. The response to benzaldehyde only lasted during treatment. Most of the patients had been treated with chemotherapy or radiation therapy.

   The National Cancer Institute requested case reports from practitioners who believed their patients were helped by treatment with laetrile. An expert panel concluded that 2 of 67 patients had complete responses and 4 had a decrease in tumor size.

   Findings from 2 clinical trials conducted by the National Cancer Institute reported the following:

   • A phase I study tested doses, schedules, and ways to give amygdalin in 6 cancer patients. Researchers found that amygdalin caused very few side effects at the prescribed doses when given by mouth or by IV. Two patients who ate raw almonds while taking amygdalin had side effects.
   • A phase II study with 175 patients looked at what types of cancer might benefit from treatment with amygdalin. Most of the patients in this study had breast, colon, or lung cancer. In about half of the patients, cancer had grown by the end of the treatment. Cancer had grown in all patients 7 months after treatment ended. Patients reported improved symptoms, such as the ability to work or do other activities. These improvements did not last after treatment ended.
5. Have any side effects or risks been reported from laetrile?

   The side effects of laetrile treatment include the following:

   • Nausea and vomiting.
   • Headache.
   • Dizziness.
   • Blue color of the skin caused by a lack of oxygen in the blood.
   • Liver damage.
   • Very low blood pressure.
   • Droopy upper eyelid.
   • Trouble walking caused by damaged nerves.
   • Fever.
   • Confusion.
   • Coma.
   • Death.

   The side effects of laetrile depend on the way it is given. Side effects are worse when laetrile is given by mouth. While taking laetrile, side effects get worse when:

   • Eating raw almonds or crushed fruit pits.
   • Eating certain types of fruits and vegetables, such as celery, peaches, bean sprouts, and carrots.
   • Taking high doses of vitamin C.
6. Is laetrile approved by the FDA for use as a cancer treatment in the United States?

   The U.S. Food and Drug Administration (FDA) has not approved laetrile as a treatment for cancer or any other medical condition. Laetrile is made in Mexico. The way that laetrile is made is not regulated by the FDA, so batches of laetrile may vary in purity and contents.

Complementary and alternative medicine (CAM)—also called integrative medicine—includes a broad range of healing philosophies, approaches, and therapies. A therapy is generally called complementary when it is used in addition to conventional treatments; it is often called alternative when it is used instead of conventional treatment. (Conventional treatments are those that are widely accepted and practiced by the mainstream medical community.) Depending on how they are used, some therapies can be considered either complementary or alternative. Complementary and alternative therapies are used in an effort to prevent illness, reduce stress, prevent or reduce side effects and symptoms, or control or cure disease.

Unlike conventional treatments for cancer, complementary and alternative therapies are often not covered by insurance companies. Patients should check with their insurance provider to find out about coverage for complementary and alternative therapies.

Cancer patients considering complementary and alternative therapies should discuss this decision with their doctor, nurse, or pharmacist as they would any type of treatment. Some complementary and alternative therapies may affect their standard treatment or may be harmful when used with conventional treatment.

It is important that the same scientific methods used to test conventional therapies are used to test CAM therapies. The National Cancer Institute and the National Center for Complementary and Integrative Health (NCCIH) are sponsoring a number of clinical trials (research studies) at medical centers to test CAM therapies for use in cancer.

Conventional approaches to cancer treatment have generally been studied for safety and effectiveness through a scientific process that includes clinical trials with large numbers of patients. Less is known about the safety and effectiveness of complementary and alternative methods. Few CAM therapies have been tested using demanding scientific methods. A small number of CAM therapies that were thought to be purely alternative approaches are now being used in cancer treatment—not as cures, but as complementary therapies that may help patients feel better and recover faster. One example is acupuncture. According to a panel of experts at a National Institutes of Health (NIH) meeting in November 1997, acupuncture has been found to help control nausea and vomiting caused by chemotherapy and pain related to surgery. However, some approaches, such as the use of laetrile, have been studied and found not to work and to possibly cause harm.

The NCI Best Case Series Program which was started in 1991, is one way CAM approaches that are being used in practice are being studied. The program is overseen by the NCI’s Office of Cancer Complementary and Alternative Medicine (OCCAM). Health care professionals who offer alternative cancer therapies submit their patients’ medical records and related materials to OCCAM. OCCAM carefully reviews these materials to see if any seem worth further research.

When considering complementary and alternative therapies, patients should ask their health care provider the following questions:

National Center for Complementary and Integrative Health (NCCIH)

The National Center for Complementary and Integrative Health (NCCIH) at the National Institutes of Health (NIH) facilitates research and evaluation of complementary and alternative practices, and provides information about a variety of approaches to health professionals and the public.

CAM on PubMed

NCCIH and the NIH National Library of Medicine (NLM) jointly developed CAM on PubMed, a free and easy-to-use search tool for finding CAM-related journal citations. As a subset of the NLM's PubMed bibliographic database, CAM on PubMed features more than 230,000 references and abstracts for CAM-related articles from scientific journals. This database also provides links to the websites of over 1,800 journals, allowing users to view full-text articles. (A subscription or other fee may be required to access full-text articles.)

Office of Cancer Complementary and Alternative Medicine

The NCI Office of Cancer Complementary and Alternative Medicine (OCCAM) coordinates the activities of the NCI in the area of complementary and alternative medicine (CAM). OCCAM supports CAM cancer research and provides information about cancer-related CAM to health providers and the general public via the NCI website.

National Cancer Institute (NCI) Cancer Information Service

U.S. residents may call the Cancer Information Service (CIS), NCI's contact center, toll free at 1-800-4-CANCER (1-800-422-6237) Monday through Friday from 9:00 am to 9:00 pm. A trained Cancer Information Specialist is available to answer your questions.

Food and Drug Administration

The Food and Drug Administration (FDA) regulates drugs and medical devices to ensure that they are safe and effective.

Federal Trade Commission

The Federal Trade Commission (FTC) enforces consumer protection laws. Publications available from the FTC include: