Allopurinol has 34 known drug interactions based on U.S. FDA drug labeling data. Of these, 2 are contraindicated combinations that should be avoided entirely. 17 are classified as major interactions requiring close medical supervision. Notable interactions include combinations with Capecitabine, Pegloticase, Amoxicillin. Patients taking Allopurinol should inform their healthcare provider of all current medications — including over-the-counter drugs and supplements — to avoid potentially harmful combinations. Data sourced from OpenFDA and the NIH National Library of Medicine.
- Total
- 34
- Contraindicated
- 2
- Major
- 17
- Moderate
- 10
- Minor
- 4
Contraindicated (2)
- Allopurinol + Capecitabine— Avoid concomitant use; allopurinol may decrease concentration of capecitabine's active metabolites, reducing efficacy.
- Allopurinol + Pegloticase— Discontinue and refrain from initiating treatment with allopurinol when using pegloticase.
Major (17)
- Allopurinol + Amoxicillin— 7 DRUG INTERACTIONS • The following drugs may increase the risk of serious skin reactions: bendamustine, thiazide diuret…
- Allopurinol + Ampicillin— 7 DRUG INTERACTIONS • The following drugs may increase the risk of serious skin reactions: bendamustine, thiazide diuret…
- Allopurinol + Andthiazide— May increase risk of skin rash and hypersensitivity; renal impairment further increases risk. Monitor kidney function an…
- Allopurinol + Azathioprine— Concomitant use requires dose reduction of azathioprine as recommended in its prescribing information.
- Allopurinol + Bendamustine— Concomitant use may increase the risk of severe skin rash and hypersensitivity reactions.
- Allopurinol + Bleomycin— Increases bone marrow suppression in patients with neoplastic disease (except leukemia). Blood count monitoring recommen…
- Allopurinol + Chlorpropamide— Intervention Avoid the use of allopurinol tablets during treatment with capecitabine Chlorpropamide Clinical Impact Allo…
- Allopurinol + Cyclophosphamide— Increases bone marrow suppression in patients with neoplastic disease (except leukemia). Blood count monitoring recommen…
- Allopurinol + Cyclosporine— Allopurinol increases cyclosporine concentrations, increasing risk of adverse reactions. Increase monitoring frequency a…
- Allopurinol + Dicumarol— Allopurinol prolongs the half-life of anticoagulant dicumarol.
- Allopurinol + Doxorubicin— Increases bone marrow suppression in patients with neoplastic disease (except leukemia). Blood count monitoring recommen…
- Allopurinol + Fluorouracil— Allopurinol may decrease anti-tumor activity due to suppression of phosphorylation of 5-fluorouracil. Concomitant admini…
- Allopurinol + Mechloroethamine— Increases bone marrow suppression in patients with neoplastic disease (except leukemia). Blood count monitoring recommen…
- Allopurinol + Mercaptopurine— Concomitant use requires dose reduction of mercaptopurine as recommended in its prescribing information.
- Allopurinol + Procarbazine— Increases bone marrow suppression in patients with neoplastic disease (except leukemia). Blood count monitoring recommen…
- Allopurinol + Warfarin— CYP1A2 inhibitor that increases warfarin effect and INR; requires close INR monitoring
- Allopurinol + Warfarin Sodium— CYP1A2 inhibitor that increases warfarin effect and INR; requires closer INR monitoring.
Moderate (10)
- Allopurinol + Amoxicillin And Clavulanate Potassium— Concurrent administration increases incidence of rashes compared to amoxicillin alone. Mechanism unclear but may be rela…
- Allopurinol + Amoxicillin Oral Susp— Concurrent use increases the incidence of rashes compared to Amoxicillin alone. The mechanism is unclear.
- Allopurinol + Ampicillin Injection— Concurrent administration substantially increases incidence of skin rashes compared to ampicillin alone. Mechanism of po…
- Allopurinol + Ampicillin Sodium— Concurrent administration substantially increases incidence of skin rashes compared to ampicillin alone. Mechanism of po…
- Allopurinol + Ampicillin Sodium And Sulbactam Sodium— Concurrent administration of allopurinol and ampicillin substantially increases the incidence of rashes in patients comp…
- Allopurinol + Pentostatin— Both drugs associated with skin rashes. Combined use did not increase rash incidence in clinical studies, but one report…
- Allopurinol + Purixan— PURIXAN dose should be reduced when co-administered with allopurinol due to interaction.
- Allopurinol + Riluzole— Hepatotoxic drug; riluzole-treated patients taking this may have increased risk for hepatotoxicity.
- Allopurinol + Theophylline— Allopurinol at doses ≥600 mg/day decreases theophylline clearance, resulting in approximately 25% increase in serum conc…
- Allopurinol + Vonoprazan Fumarate— Increased incidence of rashes reported with concurrent allopurinol and amoxicillin use compared to amoxicillin alone.
Minor (4)
- Allopurinol + Prazosin— Prazosin has been administered without adverse drug interaction with allopurinol in limited clinical experience.
- Allopurinol + Prazosin Hydrochloride— Administered without adverse drug interaction in limited clinical experience.
- Allopurinol + Terazosin— Terazosin has been used concomitantly with allopurinol in at least 50 patients with no interactions observed.
- Allopurinol + Terazosin Hydrochloride— Used concomitantly with terazosin in at least 50 patients with no interactions observed.