Ascorbic Acid (Vitamin C) and Amygdalin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ascorbic Acid (Vitamin C)
Amygdalin
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased metabolism of amygdalin, leading to increased cyanide levels
Interaction Deep Dive
Concomitant administration of amygdalin and high doses of ascorbic acid may lead to cyanide toxicity by increasing the conversion of amygdalin to hydrogen cyanide and by vitamin C dependent depletion of body stores cysteine, which is used to detoxify cyanide. A case report has described severe cyanide poisoning after the first therapeutic dose of amygdalin in a patient taking megadoses of vitamin C1.
Why it happens (mechanism)
Increased hydrolysis of amygdalin, leading to increased levels of the metabolite hydrogen cyanide, also reduced body stores of cysteine, which detoxifies cyanide.
Literature reports
1 report — tap to read
a) Life-threatening cyanide toxicity developed after the first dose of amygdalin in a 68-year old patient taking megadoses of ascorbic acid. Both supplements were part of a complementary treatment regimen used in addition to radiotherapy for locally advanced urothelial carcinoma of the bladder. The total daily intake of ascorbic acid was 4800 milligrams; the first amygdalin dose was 3000 milligrams. Approximately 2.5 hours after the ingestion of amygdalin, the patient presented to the emergency room complaining of dizziness and malaise; her Glasgow Coma Score (GCS) was 13 and her heart rate was 136 beats per minute. A short time later she had 2 generalized tonic-clonic seizures with a postictal GCS of 5. Intubation and mechanical ventilation were required. Serial blood gas analysis revealed severe lactic acidosis. The patient recovered after treatment with oral administration of activated charcoal and a 30 minute intravenous infusion of hydroxocobalamin (5 grams). The authors suggest that the mechanism of this interaction involved 2 factors: 1) the increased hydrolysis of amygdalin due to megadoses of vitamin C, which led to increased levels of hydrogen cyanide, and 2) the high doses of vitamin C may have decreased body stores of cysteine, an amino acid that facilitates the detoxification of cyanide 1.
Common questions
Can I take Ascorbic Acid (Vitamin C) and Amygdalin together?
Increased metabolism of amygdalin, leading to increased cyanide levels Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ascorbic Acid (Vitamin C) and Amygdalin interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Ascorbic Acid (Vitamin C) or Amygdalin need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Bromley J, Hughes BGM, Leong DCS, et al: Life-threatening interaction between complementary medicines: cyanide toxicity following ingestion of amygdalin and vitamin C. Ann Pharmacother 2005; 39:1566-1569. DOI
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