Laetrile / AmygdalinBanned Substance

• The FDA has never approved laetrile or amygdalin as safe and effective for any medical use in the United States [1].
  
  Legally it is an unapproved "new drug," which is why selling it or shipping it across state lines is a federal offence. ^[1]

• A 1970 Investigational New Drug application from the McNaughton Foundation was approved and then rejected [1].
  
  Preclinical animal evidence indicated laetrile was unlikely to work as an anticancer agent, and there were separate questions about how the proposed study would be conducted. ^[1]

• United States v. Rutherford (1979) asked whether the FDA's safety-and-effectiveness requirement could be waived for terminally ill patients seeking an unapproved drug [2].
  
  The Supreme Court answered unanimously that it could not. Nothing in the Food, Drug and Cosmetic Act's legislative history exempts the dying, and Congress had wanted exactly that group shielded from fraudulent remedies. ^[2]

• The Rutherford ruling settled only the federal interstate-shipment ban, and a gap it left open is still worth naming.
  
  Court challenges in Oklahoma, Massachusetts, New Jersey and California had already made laetrile legal inside more than 20 US states during the 1970s [1]. Per NCI, that state-versus-federal split was never fully resolved for intrastate use. ^[1]

• Enforcement did not stop with the ruling. In 2006 a federal judge in Miami granted the FDA a preliminary injunction halting laetrile sales by three internet sellers [3].
  
  In May 2024 the FDA warned the public after state lab testing found toxic amygdalin levels in bitter apricot seed products sold online [8]. ^[8]

• Laetrile's promoters have long framed the ban as a suppression campaign by the FDA, the pharmaceutical industry and organised medicine.
  
  That account is not supported by the clinical evidence NCI and Cochrane reviewed — the trials were run, and they found no anticancer effect [1]. ^[1]

• Laetrile's harms are cyanide's harms. Hydrogen cyanide is released when amygdalin is broken down in the body, especially in the gut [1].
  
  Documented effects run from nausea, headache and dizziness through liver damage, low blood pressure, drooping eyelid, nerve damage affecting walking and fever, to confusion, coma and death. ^[1]

• Swallowing it is considerably more dangerous than injecting it. Gut bacteria carry beta-glucosidase, the enzyme that splits cyanide off the molecule [1].
  
  Raw almonds, crushed fruit pits, celery, peaches, bean sprouts and carrots supply the same enzyme, and high oral doses of vitamin C do the same job. ^[1]

• A 2015 Cochrane systematic review found no randomised or quasi-randomised controlled trials showing laetrile or amygdalin works against cancer [10].
  
  Its authors called the risk-benefit balance for cancer patients "unambiguously negative," given the cyanide-poisoning risk after oral use. A repeat search through June 2018 turned up no new eligible studies [11]. ^[10]

• Daily long-term exposure produces chronic cyanide poisoning rather than a single acute crisis [7].
  
  Reported consequences include nerve damage, vision problems, hearing loss and balance problems. ^[7]

• In one published case, a 73-year-old cancer patient swallowed 1,500 mg of amygdalin as prescribed [5].
  
  He developed encephalopathy, lactic acidosis and shock, and recovered in hospital after hydroxocobalamin, the cyanide antidote. ^[5]

• The biochemical rationale promoters offer is itself disputed. They argue tumours are rich in beta-glucosidase and poor in rhodanese, so cyanide would be liberated selectively inside a tumour [1].
  
  NCI's review notes some enzyme-distribution differences have been observed experimentally. Clinical toxicology sources counter that beta-glucosidase is far more abundant in the intestine and liver than in tumours, which undercuts the selective-release argument. ^[1]

• Amygdalin was isolated in 1830 by two French chemists [1].
  
  By 1845 it was being given as an anticancer agent in Russia, where a positive result was reported for the first patient. ^[1]

• The first recorded US use as a cancer therapy came in the early 1920s, in pill form [1].
  
  That formulation was judged too toxic and the work was abandoned. In the 1950s a purportedly nontoxic intravenous version was patented under the name Laetrile. ^[1]

• Laetrile surged back as an alternative cancer therapy through the 1970s.
  
  By 1978, more than 70,000 people in the United States were reported to have received it [1]. ^[1]

• 1970 — the McNaughton Foundation's application to study laetrile formally was approved, then rejected [1].
  
  1979 — the Supreme Court decided the Rutherford case [2].
  
  1980 — the federal ban on interstate shipment was upheld, and US laetrile use fell sharply afterwards. ^[1]

• An NCI-sponsored phase II trial completed in 1982 gave IV amygdalin to 175 evaluable patients for 21 days, then oral maintenance [1].
  
  One patient met response criteria, a partial response lasting 10 weeks. 54% had measurable disease progression by the end of the IV phase, and all had progressed seven months after finishing. ^[1]

• 2006 — the FDA obtained a preliminary injunction closing three internet laetrile sellers [3].
  
  The substance carried on being marketed online afterwards under the aliases amygdalin and "vitamin B17." ^[3]

• 2015 — a Cochrane systematic review found no controlled trials of laetrile for cancer and called its risk-benefit balance unambiguously negative [10].
  
  May 2024 — the FDA warned consumers after state lab testing found toxic amygdalin levels in bitter apricot seed products sold online [8]. ^[10]

• Laetrile is still manufactured and administered as an anticancer therapy today, mainly by clinics in Mexico and by some clinics inside the United States [1].
  
  The federal ban has not stopped that. ^[1]

These are poisoning figures from toxicology and case literature, not a dosing range.

Oral amygdalin is estimated at roughly 40 times more potent than the intravenous form at liberating cyanide, because of enzymatic conversion in the gut [5]. A single 500 mg laetrile tablet may hold between 2.5 and 25 mg of hydrogen cyanide, depending on formulation [6].

In the documented case, 1,500 mg of amygdalin swallowed at once yielded an estimated 90 mg of cyanide — about 1.8 times a commonly cited 50 mg minimum lethal dose [5].

Lethal-dose estimates disagree across sources, and none is a precise cutoff.

EFSA's contaminants panel cites 0.5–3.5 mg/kg body weight [4]. A Wikipedia toxicology summary cites 0.6–1.5 mg/kg, and LITFL gives a flat 60–90 mg for an adult.

Raw apricot kernels carry the same compound. EFSA estimates an adult stays under its acute reference dose at about three small kernels (~370 mg), and a toddler at roughly half a kernel [4]. ^[4]

Symptoms typically begin within about 30 minutes of ingestion and progress quickly [5].

Early signs are vomiting, abdominal pain, weakness, difficulty breathing, bluish skin or lips, and lightheadedness [8]. Severe poisoning brings seizures, stupor, abnormal heart rhythms, metabolic acidosis, dangerously low blood pressure and cardiovascular collapse.

The FDA's instruction is to stop using the product and contact a healthcare provider immediately, even if the exposure was not recent [8]. For serious symptoms, call 911 or your state poison control centre.

In hospital, hydroxocobalamin is now the generally preferred antidote — its cobalt atom binds cyanide more tightly than cytochrome oxidase does, pulling it away from cells [5]. It is often paired with sodium thiosulfate, which supplies the sulfur that the body's own rhodanese enzyme needs to convert cyanide into thiocyanate [13].

Older kits — dicobalt edetate, or amyl nitrite and sodium nitrite regimens — still appear in toxicology literature. Dicobalt edetate carries meaningful toxicity of its own if given when cyanide poisoning is not actually present, which is why it now sits second [13]. ^[8]