Allopurinol and Aluminum Hydroxide: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Allopurinol
Aluminum Hydroxide
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
Decreased allopurinol effectiveness
Interaction Deep Dive
The concurrent use of aluminum hydroxide and allopurinol has been reported to result in a decreased ability of allopurinol to reduce uric acid concentrations. The result was a 50% increase in uric acid concentrations when both drugs were taken together1. Recommend taking aluminum hydroxide at least 3 hours after allopurinol administration.
Why it happens (mechanism)
Decreased allopurinol absorption
Literature reports
1 report — tap to read
a) In three patients on chronic hemodialysis, combined allopurinol therapy (300 mg daily) with aluminum hydroxide (5.7 g daily) failed to result in reductions in uric acid serum concentrations; however, spacing the dose of allopurinol 3 hours prior to antacid administration resulted in expected decreases in uric acid levels. In one patient, rechallenge with concomitant use of both drugs resulted in an increase in uric acid concentrations (from 8.9 to 13.4 mg%) 1.
Common questions
Can I take Allopurinol and Aluminum Hydroxide together?
Decreased allopurinol effectiveness Always confirm with your pharmacist or prescriber before making any change.
How serious is the Allopurinol and Aluminum Hydroxide 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 Aluminum Hydroxide 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 (1)
- Weissman I & Krivoy N: Interaction of aluminum hydroxide and allopurinol in patients on chronic hemodialysis. Ann Intern Med 1987; 107:787. PubMed
Keep reading about Allopurinol
Keep reading about Aluminum Hydroxide
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist