Cassava (Bitter Manioc Linamarin) and Apricot Kernel (Amygdalin / Laetrile) Ingestion: Delayed Gut Cyanide Poisoning¶

Eating improperly soaked or undercooked bitter cassava (Manihot esculenta, manioc/yuca), chewing bitter apricot kernels, crushed peach/cherry/plum pits, or bitter almonds, or swallowing alternative-medicine "Vitamin B17" (amygdalin or laetrile) supplements causes life-threatening delayed gastrointestinal Hydrogen Cyanide (HCN) poisoning. Call your local emergency number (911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom) or consult our international emergency numbers directory immediately, and tell the dispatcher that the patient requires intravenous Hydroxocobalamin (Cyanokit) or the Cyanide Antidote Kit (Sodium Thiosulfate / Sodium Nitrite). While awaiting paramedics, align your immediate care with our cyanide and industrial gas inhalation first aid guide, differentiate the bright-red blood of cyanide toxicity from chocolate-brown methemoglobinemia, and prepare for status epilepticus prolonged seizures or CPR.

Unlike inhaled hydrogen cyanide gas (which causes collapse within 10 to 60 seconds), swallowing cyanogenic glycosides, specifically linamarin (in bitter cassava, lima beans, and flaxseed) or amygdalin / prunasin (in bitter apricot kernels, bitter almonds, Rosaceae fruit stones, and bamboo shoots), features a deceptive 30-minute to 4-hour symptom-free latency window. During this silent period, plant and intestinal beta-glucosidase and hydroxynitrile lyase enzymes steadily hydrolyze the swallowed glycosides inside the alkaline small intestine and colon, releasing a continuous, lethal surge of hydrogen cyanide (HCN) into the portal bloodstream. Absorbed cyanide binds with extreme affinity to the ferric (Fe3+) iron atom of mitochondrial cytochrome c oxidase (Complex IV), completely halting cellular aerobic respiration even though the patient's arteries and veins remain saturated with oxygen (arterialization of venous blood). Without rapid administration of 100% supplemental oxygen, gastrointestinal decontamination, and intravenous Hydroxocobalamin (5 grams IV) or Sodium Thiosulfate (12.5 grams IV) + Sodium Nitrite (300 mg IV), victims rapidly progress from dizziness, vomiting, and deep gasping tachypnea (Kussmaul breathing) to refractory high-anion-gap lactic acidosis (serum lactate > 8 to 10 mmol/L), generalized seizures, bradycardic arrest, and death.

+-------------------------------------------------------------------------+
|       CYANOGENIC GLYCOSIDE DELAYED GUT CYANIDE TRIAGE TIMELINE          |
+-------------------------------------------------------------------------+
|  0 TO 60 MINUTES (THE SILENT ENZYMATIC HYDROLYSIS WINDOW):              |
|  * Victim eats bitter Apricot Kernels, Laetrile, or Bitter Cassava      |
|  * Plant beta-glucosidase (emulsin/linamarase) + Human gut microflora   |
|    cleave Amygdalin/Linamarin -> Mandelonitrile/Acetone Cyanohydrin     |
|    -> Lethal HYDROGEN CYANIDE (HCN) absorbed across intestinal wall     |
|  * Immediate Action: Call 911/112/999; give Activated Charcoal (< 1-2h) |
+-------------------------------------------------------------------------+
|  30 MINUTES TO 4 HOURS (ONSET OF CELLULAR HYPOXIA / HISTOTOXIC SHOCK):  |
|  * Early Signs: Headache, dizziness, anxiety, nausea/vomiting, cherry-  |
|    red flushed skin, tachycardia, and deep gasping hyperventilation     |
|  * Late Signs: Coma, tonic-clonic seizures, hypotension, bradycardia    |
|  * Lab Clues: Venous blood looks bright "cherry-red" (PvO2 > 50-60 mmHg)|
|    + Serum Lactate > 8 to 10 mmol/L (confirms acute cyanide poisoning)  |
+-------------------------------------------------------------------------+
|  DEFINITIVE HOSPITAL ANTIDOTAL RESCUE:                                  |
|  * Give 100% High-Flow Oxygen (ALWAYS safe & beneficial in cyanide)     |
|  * 1st Choice Antidote: IV Hydroxocobalamin (Cyanokit) 5 g (70 mg/kg)   |
|    + IV Sodium Thiosulfate 12.5 g (25% solution, 50 mL) for slow release|
|  * 2nd Choice Antidote: IV Sodium Nitrite (300 mg) + Sodium Thiosulfate |
+-------------------------------------------------------------------------+

Do this now¶

1. Call emergency services and Poison Control immediately, even if the person still feels completely normal. Dial 911 (US and Canada), 112 (European Union), 999 (United Kingdom), 000 (Australia), or 111 (New Zealand). Tell the dispatcher the exact substance swallowed (bitter apricot kernels, laetrile / amygdalin tablets, bitter cassava / manioc, or bitter almonds), how many kernels or grams were chewed, and the time of ingestion so the receiving hospital can prepare Hydroxocobalamin (Cyanokit) and Sodium Thiosulfate at the resuscitation bay before the patient crashes.
2. Never induce vomiting, and never perform mouth-to-mouth resuscitation without a barrier mask. If a patient who swallowed cyanogenic glycosides or cyanide salts vomits, gastric acid converts cyanide into volatile hydrogen cyanide (HCN) gas (which smells weakly like bitter almonds to the 40% to 60% of people genetically able to detect the odor). If the patient stops breathing, use a bag-valve-mask (BVM) or a one-way pocket CPR mask with high-flow oxygen rather than direct mouth-to-mouth contact.
3. Administer high-flow 100% Oxygen as soon as paramedics arrive. Even though pulse oximetry (SpO2) will read 98% to 100% because poisoned cells cannot extract oxygen from the blood, administering 100% normobaric oxygen increases dissolved plasma oxygen tension, competes with cyanide at cytochrome c oxidase binding sites, and enhances the antidotal synergy of sodium thiosulfate and hydroxocobalamin.
4. Withhold oral Vitamin C (Ascorbic Acid) supplements. If someone took apricot kernels or oral laetrile, check whether they also took high-dose Vitamin C. High-dose oral Vitamin C (> 1 to 3 grams) accelerates the gastrointestinal conversion of amygdalin into hydrogen cyanide and depletes endogenous cysteine stores needed by the liver's rhodanese detoxifying enzyme.
5. Save the package, seed bag, or leftover cassava root. Bring the container of apricot kernels, B17 supplement bottle, or raw cassava tuber to the emergency department. Count or estimate the exact number of kernels eaten: chewing just 5 to 10 bitter apricot kernels in a young child or 20 to 60 bitter apricot kernels (0.5 to 3.5 mg/kg of cyanide equivalent) in an adult can produce life-threatening or fatal cyanide poisoning.

Decision tree: Delayed gut cyanogenic glycoside triage and antidote selection¶

flowchart TD
    A["Ingestion of Bitter Cassava, Bitter Apricot Kernels, Fruit Pits, or Laetrile (Amygdalin)"] --> B{"What Was Ingested & How?"}
    B -->|"1-3 Whole Uncrushed Cherry/Plum/Peach Pits or a Few Apple Seeds"| C["Low Risk: Intact seed coat prevents Amygdalin release; Observe at home unless chewed"]
    B -->|"Chewed/Ground Bitter Apricot Kernels, Bitter Almonds, Laetrile Tablets, or Bitter Cassava"| D["HIGH RISK FOR DELAYED GUT HCN POISONING (Latency 30 min to 4 hours)"]
    D --> E["Call 911/112/999; Apply 100% High-Flow Oxygen; Give Activated Charcoal (1 g/kg up to 50-100 g) if < 1-2 Hours and Awake"]
    E --> F["Order Stat Venous Blood Gas (VBG), Arterial Blood Gas (ABG), Serum Lactate, and Basic Metabolic Panel"]
    F --> G{"Assess Clinical Severity & Serum Lactate"}
    G -->|"Asymptomatic & Lactate < 3.0 mmol/L"| H["Observe in ED/ICU for Minimum 6 to 12 Hours (Delayed Gut Hydrolysis); Repeat Lactate q1-2h"]
    G -->|"Altered Mental Status, Seizures, Hypotension, Tachypnea, OR Lactate >= 8-10 mmol/L"| I["IMMEDIATE ANTIDOTE ADMINISTRATION (Do NOT wait for lab cyanide levels)"]
    I --> J{"Which Cyanide Antidote Is Immediately Available?"}
    J -->|"Hydroxocobalamin (Cyanokit) Available (1st Choice)"| K["Infuse Hydroxocobalamin 5 g IV (70 mg/kg in kids) over 15 min + Add Sodium Thiosulfate 12.5 g IV for ongoing gut release"]
    J -->|"Only Nitrite + Thiosulfate Kit Available"| L["Give Sodium Nitrite 300 mg IV (10 mL of 3%) over 2-4 min (Check Hemoglobin first) -> Follow with Sodium Thiosulfate 12.5 g IV"]

Pathophysiology: How plant glycosides turn into Hydrogen Cyanide (HCN) inside the human gut¶

Over 2,500 plant species synthesize cyanogenic glycosides as a natural chemical defense against herbivores. In the intact plant leaf, root, or seed, the cyanogenic glycoside is stored safely inside cellular vacuoles, physically separated from its activating hydrolytic enzymes (beta-glucosidase and hydroxynitrile lyase), which sit in the plant cell wall or cytoplasm.

1. The two-step enzymatic cleavage of Amygdalin and Linamarin¶

+-------------------------------------------------------------------------+
|       BIOCHEMICAL CONVERSION OF AMYGDALIN & LINAMARIN TO CYANIDE        |
+-------------------------------------------------------------------------+
|                                                                         |
|  PATHWAY 1: APRICOT KERNELS, BITTER ALMONDS, PEACH/CHERRY PITS, LAETRILE|
|  Amygdalin (D-mandelonitrile-beta-D-gentiobioside)                      |
|      |                                                                  |
|      |  Step 1: Beta-Glucosidase (Plant 'Emulsin' when chewed OR        |
|      |          Human intestinal microflora beta-glucosidase in gut)    |
|      v                                                                  |
|  Prunasin + Glucose  --->  Mandelonitrile + Glucose                     |
|                                  |                                      |
|                                  |  Step 2: Hydroxynitrile Lyase OR     |
|                                  |  Spontaneous dissociation in         |
|                                  |  alkaline duodenum (pH > 6.5)        |
|                                  v                                      |
|              Benzaldehyde  +  HYDROGEN CYANIDE (HCN)                    |
|              (Almond odor)    (Lethal Complex IV inhibitor)             |
|                                                                         |
+-------------------------------------------------------------------------+
|  PATHWAY 2: BITTER CASSAVA (MANIOC / YUCA), LIMA BEANS, BAMBOO SHOOTS   |
|  Linamarin (alpha-hydroxyisobutyronitrile-beta-D-glucopyranoside)       |
|      |                                                                  |
|      |  Step 1: Linamarase (plant beta-glucosidase) OR Gut bacteria     |
|      v                                                                  |
|  Acetone Cyanohydrin + Glucose                                          |
|      |                                                                  |
|      |  Step 2: Hydroxynitrile Lyase OR Spontaneous breakdown at pH > 5 |
|      v                                                                  |
|  Acetone  +  HYDROGEN CYANIDE (HCN)                                     |
+-------------------------------------------------------------------------+

• Why oral Laetrile / Amygdalin is 40 times more toxic than intravenous Laetrile: Fraudulent "Vitamin B17" promoters historically claimed laetrile was safe because intravenous injections in animals caused minimal immediate toxicity. When injected intravenously, sterile amygdalin bypasses the digestive tract and is excreted > 90% unchanged in the urine because human blood and tissues lack beta-glucosidase enzymes. When taken by mouth, however, human colonic and small-intestinal bacteria possess abundant beta-glucosidase activity. Even if a person boils apricot kernels to denature the plant's own emulsin enzyme, or swallows purified pharmaceutical laetrile tablets, their own intestinal bacteria cleave the glycoside 1 to 4 hours later in the lower ileum and colon, flooding the portal vein with lethal hydrogen cyanide (HCN).
• Why Bitter Cassava poisons families during droughts and food shortages: Cassava cultivars are classified into "sweet" cassava (< 50 milligrams of HCN equivalent per kilogram of fresh root, located mostly in the outer peel) and "bitter" cassava (100 to > 500 milligrams of HCN per kilogram distributed throughout the entire starchy flesh). During severe droughts, cassava plants increase their linamarin content three- to five-fold. Safe traditional preparation of bitter cassava requires peeling, grating/crushing, soaking/fermenting in water for 3 to 5 days (allowing endogenous linamarase to convert linamarin into acetone cyanohydrin), and then sun-drying or roasting at high heat to volatilize the acetone cyanohydrin and HCN gas. If a hungry family boils un-soaked bitter cassava roots for only 20 minutes, or eats half-soaked cassava within 24 hours, the heat denatures the linamarase enzyme before the linamarin is broken down, leaving intact linamarin and acetone cyanohydrin in the food. Once swallowed, acetone cyanohydrin spontaneously decomposes into lethal HCN inside the alkaline duodenum, while gut bacteria hydrolyze the remaining linamarin over the next 2 to 6 hours.

Comparison of dietary cyanogenic glycoside sources and clinical toxicity¶

Bedside diagnosis: How to confirm acute Cyanide poisoning before reference labs return¶

Quantitative whole-blood cyanide testing takes hours or days at reference laboratories and is never available in time to guide emergency resuscitation. Clinicians confirm acute gut cyanide poisoning at the bedside in 5 minutes using three immediate diagnostic fingerprints:

1. "Arterialization" of Venous Blood (Cherry-Red Venous Blood and Narrow A-V O2 Gap)¶

• Mechanism: Because cyanide locks mitochondrial cytochrome c oxidase (Complex IV) in its oxidized (Fe3+) state, peripheral tissues cannot extract oxygen from passing oxyhemoglobin.
• Bedside sign: When the nurse or phlebotomist draws a peripheral venous blood sample, the venous blood looks bright "cherry-red" (indistinguishable from arterial blood) rather than dark purple-red.
• Blood gas confirmation: Compare a simultaneous Arterial Blood Gas (ABG) and central/peripheral Venous Blood Gas (VBG):
• While arterial PaO2 and pulse oximetry (SpO2) remain normal (97% to 100%) early on, the venous oxygen saturation (ScvO2 or SvO2) exceeds 85% to 90% and venous PvO2 exceeds 50 to 60 mmHg.
• The arteriovenous oxygen difference (A-V O2 gradient) narrows to less than 1 to 2 vol%, proving histotoxic cellular hypoxia (shared only by cyanide, hydrogen sulfide, sodium azide, and high-oxygen resuscitation).
• Fundoscopic confirmation: Direct ophthalmoscopy of the retina shows retinal veins that are the exact same bright red color as the retinal arteries.

2. Serum Lactate >= 8 to 10 mmol/L (The Gold-Standard Surrogate Marker)¶

• Because aerobic ATP synthesis is shut down (producing only 2 ATP molecules per glucose via anaerobic glycolysis instead of 36 ATP), cells convert pyruvate rapidly into lactic acid.
• Clinical toxicology studies (Baud et al., New England Journal of Medicine) established that in a non-smoke-inhalation poisoning patient, a plasma lactate concentration of >= 8 mmol/L (72 mg/dL) (or >= 10 mmol/L in smoke inhalation) has > 90% sensitivity and specificity for severe acute cyanide poisoning (blood cyanide > 40 micromoles/L or > 1.0 mg/L) and correlates linearly with intracellular cyanide burden.

3. The Biphasic Hemodynamic and Respiratory Curve¶

• Phase 1 (Early Chemoreceptor Stimulation, 30 to 90 minutes): Cyanide directly stimulates the carotid body chemoreceptors, triggering a sudden "cyanide gasp" followed by marked hyperventilation / tachypnea (Kussmaul breathing), sinus tachycardia, hypertension, headache, vertigo, confusion, and flushing.
• Phase 2 (Late Hypoxic Decompensation, 1 to 4 hours): As intracellular ATP collapses in the brainstem and myocardium, the patient abruptly transitions to apnea / bradypnea, profound sinus bradycardia or AV block, severe arterial hypotension, generalized tonic-clonic seizures, decerebrate posturing, and pulseless electrical activity (PEA) or asystole.

Step-by-step Hospital Antidote and Decontamination Protocol¶

Because gut hydrolysis of amygdalin and linamarin continues for hours inside the gastrointestinal tract (unlike a one-time inhalation of HCN gas), treating plant cyanogenic glycoside poisoning requires both immediate intravenous antidote rescue AND ongoing gastrointestinal decontamination + prolonged sulfur-donor infusion.

+-------------------------------------------------------------------------+
|       TWO COMPLEMENTARY ANTIDOTAL MECHANISMS FOR GUT CYANIDE            |
+-------------------------------------------------------------------------+
|  1. HYDROXOCOBALAMIN (CYANOKIT - VITAMIN B12a PRECURSOR):               |
|     Hydroxocobalamin (Co3+ - OH)  +  Cyanide (CN-)                      |
|                     |                                                   |
|                     v  (Direct equimolar chelation in blood & cells)    |
|     Cyanocobalamin (Vitamin B12 - Non-toxic, excreted in crimson urine) |
|     * Pros: Instant onset, does NOT lower blood pressure, does NOT form |
|       methemoglobin (safe in children, pregnancy, and anemia)           |
+-------------------------------------------------------------------------+
|  2. SODIUM THIOSULFATE (SULFUR DONOR FOR HEPATIC RHODANESE):            |
|     Thiosulfate (S2O3 2-) + Cyanide (CN-) ---[Rhodanese]---> Thiocyanate|
|     * Pros: Provides continuous sulfur substrate to detoxify ongoing    |
|       slow release of HCN from apricot kernels or cassava in the gut    |
|     * CRITICAL RULE: Infuse Hydroxocobalamin and Sodium Thiosulfate     |
|       through SEPARATE IV lines (or flush thoroughly between them)      |
+-------------------------------------------------------------------------+

Step 1: Gastrointestinal Decontamination (Activated Charcoal and Gastric Lavage)¶

• Even though activated charcoal has a relatively low gram-for-gram capacity for pure inorganic potassium cyanide (1 gram of charcoal adsorbs -35 mg of KCN), standard adult doses (50 to 100 grams of activated charcoal) easily adsorb lethal milligram quantities of un-hydrolyzed amygdalin, linamarin, and liberated HCN in the stomach and significantly improve survival in experimental and clinical poisonings.
• If the patient presents within 1 to 2 hours of ingesting crushed bitter apricot kernels, laetrile tablets, or bitter cassava, secure the airway (intubate if obtunded) and perform gastric aspiration/lavage to physically remove remaining seed fragments, followed immediately by Activated Charcoal (1 gram/kg, up to 50 to 100 grams).

Step 2: First-Line Intravenous Antidote: Hydroxocobalamin (Cyanokit)¶

Hydroxocobalamin (Cyanokit) is the universally preferred first-line antidote for acute cyanide poisoning across North America, Europe, the UK, and Australia because it directly binds intracellular and intravascular cyanide to form harmless cyanocobalamin (Vitamin B12) without compromising oxygen-carrying hemoglobin or causing nitrites-induced vasoplegic shock.

• Adult Dose: Reconstitute 5 grams (one 5 g vial or two 2.5 g vials) of Hydroxocobalamin in 200 milliliters of 0.9% sodium chloride and infuse intravenously over 15 minutes (-15 mL/minute).
• Pediatric Dose: Infuse 70 milligrams per kilogram (70 mg/kg, up to a maximum initial dose of 5 grams) intravenously over 15 minutes.
• Mandatory Repeat Dosing for Delayed Gut Hydrolysis: In apricot kernel, laetrile, or bitter cassava poisoning, patients frequently experience a rebound surge of cyanide 2 to 6 hours after the first 5 g Hydroxocobalamin dose as intestinal bacteria continue cleaving unabsorbed glycosides in the colon. If lactic acidosis (> 4 mmol/L), hypotension, or coma recurs or persists, infuse a second 5 gram (70 mg/kg pediatric) dose of Hydroxocobalamin over 15 minutes to 2 hours.
• Expected Side Effects (Harmless Chromaturia & Lab Interference): Hydroxocobalamin is an intense burgundy-red pigment. It immediately turns the patient's skin, tears, sweat, plasma, and urine deep crimson-red (chromaturia) for 2 to 7 days (and up to 28 days in urine). Warn the laboratory that hydroxocobalamin spectrophotometrically interferes with colorimetric assays for creatinine, bilirubin, transaminases, magnesium, and carboxyhemoglobin/methemoglobin co-oximetry, draw baseline blood tubes immediately before starting the red infusion.

Step 3: Co-Administration of Intravenous Sodium Thiosulfate (12.5 Grams)¶

Because the body's natural cyanide-detoxifying enzyme, mitochondrial rhodanese (thiosulfate sulfurtransferase) in the liver and skeletal muscle, quickly runs out of endogenous sulfur donors during prolonged gut glycoside absorption, administering Intravenous Sodium Thiosulfate provides an inexhaustible supply of sulfane sulfur to convert cyanide into harmless thiocyanate (SCN-), which is excreted by the kidneys: * Adult Dose: 12.5 grams (50 milliliters of a 25% Sodium Thiosulfate solution) infused intravenously over 10 to 30 minutes. * Pediatric Dose: 250 milligrams per kilogram (1.0 mL/kg of 25% solution, or 412.5 mg/kg [1.65 mL/kg] depending on formulation hydration, up to 12.5 grams) intravenously over 10 to 30 minutes.

Step 4: Alternative Antidote Protocol (When Hydroxocobalamin Is Unavailable): Sodium Nitrite + Sodium Thiosulfate (Nithiodote) or Dicobalt Edetate (Kelocyanor)¶

In many developing regions where bitter cassava outbreaks occur, or in smaller rural clinics without Cyanokit, clinicians use the classic two-step Nitrite + Thiosulfate regimen: 1. Amyl Nitrite (Inhaled bridge before IV access): Crush an ampoule of amyl nitrite (0.3 mL) in gauze and hold it under the patient's nose (or over the bag-valve-mask intake) for 15 to 30 seconds of every minute while establishing IV access. 2. Intravenous Sodium Nitrite (3% solution): * Mechanism: Oxidizes 10% to 20% of circulating ferrous hemoglobin (Fe2+) into ferric methemoglobin (Fe3+). Because cyanide has a high affinity for Fe3+, methemoglobin pulls cyanide off mitochondrial cytochrome c oxidase to form cyanmethemoglobin. * Adult Dose: 300 milligrams (10 milliliters of 3% Sodium Nitrite) infused intravenously over 2 to 4 minutes (monitor blood pressure closely, as nitrites cause potent vasodilation and hypotension). * Pediatric Dose (Must Adjust for Hemoglobin to Prevent Fatal Methemoglobinemia): 6 to 10 mg/kg (0.2 to 0.33 mL/kg of 3% solution, maximum 300 mg), strictly reduced if the child is anemic (hemoglobin < 10 g/dL). Check methemoglobin levels at 30 minutes and keep total methemoglobin strictly below 20% to 30%. 3. Intravenous Sodium Thiosulfate (25% solution): Follow immediately (after flushing the line) with 12.5 grams (50 mL of 25% solution; pediatric 1.0 to 1.65 mL/kg) to convert cyanmethemoglobin permanently into urinary thiocyanate. 4. Dicobalt Edetate (Kelocyanor - UK/Commonwealth Legacy Stock): Administered as 300 mg (20 mL) IV over 1 minute followed immediately by 50 mL of 50% Dextrose. Because free cobalt causes severe cardiac arrhythmias, facial/laryngeal edema, and hypotension if no cyanide is present in the blood, Dicobalt Edetate must ONLY be given to patients with unequivocal, severe clinical cyanide poisoning (coma, apnea, or shock), never prophylactically to asymptomatic patients.

Safe preparation of Cassava and regulatory limits on Apricot Kernels¶

• How to detoxify Bitter Cassava at home (The WHO / FAO "Wetting Method"):
• Grate or pound the peeled cassava root into a fine mash or flour (rupturing cell walls so linamarase contacts linamarin).
• Soak / ferment the mash in water for 3 to 5 days (or if using already-dried cassava flour that still tastes bitter, mix the flour with water into a thin wet paste and spread it in a thin layer in the shade for 5 hours at 30 degrees Celsius so residual linamarase hydrolyzes the linamarin into volatile acetone cyanohydrin).
• Boil or roast thoroughly in an open pot so all acetone cyanohydrin and HCN gas evaporate into the air, and discard the soaking/boiling water.
• Regulatory warnings on Bitter Apricot Kernels:
• The European Food Safety Authority (EFSA) and UK Food Standards Agency (FSA) established an Acute Reference Dose (ARfD) of 20 micrograms/kg of cyanide, concluding that eating more than 1 to 3 small bitter apricot kernels in adults (or half of one small kernel in toddlers) exceeds the safe threshold. Both the EU (Regulation 2017/1237) and the UK ban the sale of raw bitter apricot kernels to consumers exceeding 20 mg/kg of hydrocyanic acid, and Australia/New Zealand prohibit the retail sale of raw apricot kernels as food entirely.
• In the United States and Canada, the US FDA bans laetrile (amygdalin) as an unapproved, fraudulent, and highly toxic substance, and Health Canada limits total extractable cyanide in sold apricot kernels to 20 ppm while warning adults never to consume bitter kernels.

Regional emergency and antidote access protocols¶

• United States and Canada: Call 911 immediately and dial 1-800-222-1222 (US Poison Help) or 1-844-POISON-X (1-844-764-7669 in Canada). Advanced life support (ALS) ambulances and hospital emergency departments across North America stock Hydroxocobalamin (Cyanokit, 5 g vials) and Nithiodote (Sodium Nitrite + Sodium Thiosulfate).
• United Kingdom and European Union: Call 999 (UK) or 112 (EU). Clinicians consult NPIS / TOXBASE (UK) or national EU poison centers (CAPTV, Giftnotruf). In the UK and EU, emergency departments stock Hydroxocobalamin (Cyanokit) and Sodium Thiosulfate in the immediate resuscitation antidote cupboard (Category A Antidotes required immediately at every acute hospital).
• Australia and New Zealand: Call 000 (Australia) or 111 (New Zealand), and consult the Poisons Information Centre (13 11 26 in Australia; 0800 764 766 in New Zealand) for immediate Cyanokit and Sodium Thiosulfate guidance.
• Sub-Saharan Africa, South America, and Southeast Asia: In cassava-staple regions (Democratic Republic of the Congo, Mozambique, Tanzania, Nigeria, Brazil, Indonesia, Philippines), where Cyanokit may not be stocked at rural clinics, immediate administration of 100% Oxygen + Activated Charcoal + Intravenous Sodium Thiosulfate (25%, 50 mL IV) + Intravenous Sodium Bicarbonate (to correct severe lactic acidosis) is life-saving and widely stocked.

Frequently asked questions¶

Why does cyanide poisoning from apricot kernels or bitter cassava take 1 to 4 hours to start?¶

Unlike inhaled hydrogen cyanide gas (which enters the lungs and bloodstream in seconds), apricot kernels and bitter cassava contain bound plant sugar compounds called cyanogenic glycosides (amygdalin and linamarin). These compounds are harmless until plant enzymes (activated by chewing) and human intestinal bacteria slowly snip off the sugar molecules inside the alkaline small intestine and colon, releasing free hydrogen cyanide gas into the blood 30 minutes to 4 hours after the meal.

Why is taking "Vitamin B17" (Laetrile) by mouth so much deadlier than intravenous injections?¶

Human blood and organs do not possess the beta-glucosidase enzyme required to break amygdalin down into cyanide, so when laetrile is injected into a vein, over 90% of it is excreted unchanged in the urine. When swallowed by mouth, however, the trillions of natural bacteria living inside the human small intestine and colon produce abundant beta-glucosidase enzymes that cleave oral laetrile directly into lethal hydrogen cyanide, making oral tablets roughly 40 times more toxic than intravenous doses.

What happens if a child accidentally swallows a whole cherry pit or peach stone without chewing it?¶

If a cherry pit, plum pit, peach stone, or apple seed is swallowed completely whole with its hard woody outer shell unbroken, the amygdalin stays locked safely inside the seed coat and the pit passes harmlessly out in the stool over 1 to 3 days. Cyanide poisoning only occurs when the seeds or pits are chewed, crushed, ground, blended, or cracked open before swallowing.

How do emergency doctors diagnose cyanide poisoning in 5 minutes if blood cyanide tests take days?¶

Doctors look for two unmistakable bedside signs of blocked cellular oxygen use: first, peripheral venous blood drawn from the arm looks bright "cherry-red" (just like arterial blood) with a venous oxygen saturation above 85% to 90% because poisoned mitochondria cannot extract oxygen from the blood; and second, the blood lactate level surges above 8 to 10 mmol/L due to sudden anaerobic metabolism.

Why do doctors give BOTH Hydroxocobalamin (Cyanokit) and Sodium Thiosulfate for apricot kernel poisoning?¶

A single 5-gram dose of Hydroxocobalamin (Cyanokit) immediately chelates the cyanide currently circulating in the blood and organs into harmless Vitamin B12, rescuing the heart and brain within minutes. However, because crushed apricot kernels or bitter cassava continue sitting in the intestines and releasing new cyanide for another 4 to 12 hours, adding intravenous Sodium Thiosulfate (through a separate or flushed IV line) supplies the liver's rhodanese enzyme with continuous sulfur to neutralize ongoing gut cyanide absorption.

What is "Konzo" and how is it linked to bitter cassava?¶

Konzo is a devastating, irreversible upper-motor-neuron paralysis of both legs (spastic paraparesis) that strikes children and women of childbearing age in rural Sub-Saharan Africa during droughts and famines. It occurs when families are forced to eat improperly soaked bitter cassava week after week while suffering from severe dietary protein deficiency (lacking the sulfur-containing amino acids methionine and cysteine needed by the liver to detoxify cyanide into thiocyanate).

To handle poisoning, airway, and cardiac emergencies effectively, consider completing a hands-on first aid and CPR course from the Red Cross, St John Ambulance, or a certified local training organization.

Related guides¶

• Cyanide, Hydrogen Sulfide, and Industrial Gas Inhalation First Aid
• Methemoglobinemia (Chocolate-Brown Blood), Benzocaine Spray, and Nitrate Poisoning
• Wild Mushroom Foraging (Amatoxin) and Poisonous Plant Ingestion
• Status Epilepticus, Prolonged Seizures, and Rescue Medications
• General Poisoning First Aid and Decontamination

Sources and official guidance¶

• World Health Organization (WHO) & Food and Agriculture Organization (FAO): Concise International Chemical Assessment Document 61: Hydrogen Cyanide and Cyanides: Human Health Aspects; Cyanogenic Glycosides in Cassava and Bamboo Shoots (Geneva).
• European Food Safety Authority (EFSA) Panel on Contaminants in the Food Chain: Acute health risks related to the presence of cyanogenic glycosides in raw apricot kernels and products derived from raw apricot kernels (EFSA Journal).
• U.S. Centers for Disease Control and Prevention (CDC) / ATSDR: Medical Management Guidelines for Hydrogen Cyanide, Sodium Cyanide, and Cyanogenic Compounds (United States).
• UK National Poisons Information Service (NPIS) / TOXBASE & Royal College of Emergency Medicine: Antidote Guidelines: Hydroxocobalamin (Cyanokit), Sodium Thiosulfate, and Sodium Nitrite in Acute Cyanide and Cyanogenic Glycoside Poisoning (United Kingdom).
• Baud FJ, Barriot P, Toffis V, et al. / Hall AH, Rumack BH: Elevated blood cyanide concentrations and plasma lactate in acute cyanide poisoning; Laetrile (Amygdalin) and Apricot Kernel Toxicity (New England Journal of Medicine / Annals of Emergency Medicine).