Allopurinol and Vidarabine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Allopurinol
Vidarabine
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
Neurotoxicity, tremors, impaired cognitive function
Interaction Deep Dive
Case reports of concurrent use have demonstrated an increased incidence of neurotoxicity (rhythmic tremors, impaired mentation, pain, itching and nausea). In most cases, the onset of toxicity occurred after 3 to 4 days of concurrent treatment13.
Why it happens (mechanism)
Decreased metabolism
Literature reports
2 reports — tap to read
a) Two patients with chronic lymphocytic leukemia who were receiving vidarabine and allopurinol 300 mg daily developed severe neurotoxicity consisting of coarse rhythmic tremors of extremities and facial muscles and impaired mentation which developed on the fourth day of vidarabine treatment. It was postulated that since allopurinol affects purine metabolism, perhaps concomitant use may increase levels of hypoxanthine arabinoside, the major metabolic product, leading to toxicity 1.
b) Neurological toxicity was reported in a 32-year-old female receiving vidarabine and allopurinol 2.
Common questions
Can I take Allopurinol and Vidarabine together?
Neurotoxicity, tremors, impaired cognitive function Always confirm with your pharmacist or prescriber before making any change.
How serious is the Allopurinol and Vidarabine interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
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 Allopurinol or Vidarabine 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 anything you'd monitor while I'm on both?
References (3)
- Friedman HM & Grasela T: Adenine arabinoside and allopurinol: possible adverse drug interaction (letter). N Engl J Med 1981; 304:423. DOI
- Collignon PJ & Sorrell TC: Neurological toxicity associated with vidarabine therapy. Aust N Z J Med 1983; 13:627.
- Ross AH, Julia A, & Balakrishnan C: Toxicity of adenine arabinoside in humans. J Infect Dis 1976; 133(suppl):A192-A198. PubMed
Keep reading about Allopurinol
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