Allopurinol and Probenecid: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Probenecid
No brand names on recordAllopurinol
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
An increase in probenecid concentration
Interaction Deep Dive
Two reports indicate that concomitant administration of allopurinol and probenecid have resulted in prolongation of the probenecid half-life and increases in the probenecid plasma concentration. Discontinuation of allopurinol results in probenecid levels returning to control values within three days. It has been postulated that allopurinol or its major active metabolite is an inhibitor of probenecid metabolism12.
Why it happens (mechanism)
Inhibition of probenecid metabolism
Common questions
Can I take Allopurinol and Probenecid together?
An increase in probenecid concentration Always confirm with your pharmacist or prescriber before making any change.
How serious is the Allopurinol and Probenecid interaction?
It is rated minor. Usually limited clinical impact.
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.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Allopurinol or Probenecid 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 (2)
- Tjandramaga TB & Cucinell SA: Interaction of probenecid and allopurinol in gouty subjects (abstract). Fed Proc 1971; 30:392.
- Tjandramaga TB, Cucinell SA, Israili ZH, et al: Observations on the disposition of probenecid in patients receiving allopurinol. Pharmacology 1972; 8:259-272. PubMed
Keep reading about Probenecid
Keep reading about Allopurinol
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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