AdultPediatricDosage Forms & Strengths tablet 100mg 300mg powder for injection 500mg/vial Gout Mild: 100 mg/day PO initially; increased weekly to 200-300 mg/day Moderate to severe: 100 mg/day PO initially; increased weekly to 400-600 mg/day Antineoplastic-Induced Hyperuricemia PO: 600-800 mg divided q8-12hr, starting 1-2 days before chemotherapy IV: 200-400 mg/m²/day; not to exceed 600 mg/m²/day; may administer as single infusion or in equally divided doses at 6, 8, 12 hr intervals beginning 1-2 days before chemotherapy Dosing Considerations Minimum PO dosage: 100-200 mg/day Maximum PO dosage: 800 mg/day Dosing Modifications Renal impairment CrCl 10-20 mL/min: 200 mg/day CrCl 3-10 mL/min: 100 mg/day CrCl <3 mL/min: 100 mg/day at extended intervals Dosage Forms & Strengths tablet 100mg 300mg powder for injection 500mg/vial Hyperuricemia 10 mg/kg/day PO divided q12hr; not to exceed 600 mg/day Antineoplastic-Induced Hyperuricemia PO (<6 years): 150 mg/day divided q8hr PO (6-10 years): 300 mg/day in single daily dose or divided q8hr PO (>10 years): 600-800 mg/day, starting 1-2 days before chemotherapy IV: 200 mg/m²/day initially, starting 1-2 days before chemotherapy Interaction CheckerEnter a drug name and allopurinolNo Results No Interactions Found Interactions FoundContraindicatedSerious - Use AlternativeSignificant - Monitor CloselyMinorAll Interactions Sort By: SeverityName Contraindicated (0)Serious - Use Alternative (12)azathioprineallopurinol increases levels of azathioprine by decreasing metabolism. Avoid or Use Alternate Drug. Increased risk of bone marrow toxicity.benazeprilbenazepril increases toxicity of allopurinol by unspecified interaction mechanism. Avoid or Use Alternate Drug. May increase risk for allergic or hypersensitivity reactions to allopurinol. Monitor for symptoms of hypersensitivity reactions if both drugs must be used together.captoprilcaptopril, allopurinol. Mechanism: unknown. Avoid or Use Alternate Drug. Risk of anaphylaxis, Stevens Johnson syndrome.captopril increases toxicity of allopurinol by Mechanism: unspecified interaction mechanism. Avoid or Use Alternate Drug. May increase risk for allergic or hypersensitivity reactions to allopurinol Monitor for symptoms of hypersensitivty reactions if both drugs must be used together.didanosineallopurinol increases levels of didanosine by unknown mechanism. Contraindicated.enalaprilenalapril, allopurinol. Mechanism: unknown. Avoid or Use Alternate Drug. Risk of anaphylaxis, Stevens Johnson syndrome.perindoprilperindopril, allopurinol. Mechanism: unknown. Avoid or Use Alternate Drug. Risk of anaphylaxis, Stevens Johnson syndrome.pexidartiniballopurinol and pexidartinib both increase Other (see comment). Avoid or Use Alternate Drug. Pexidartinib can cause hepatotoxicity. Avoid coadministration of pexidartinib with other products know to cause hepatoxicity.pretomanidallopurinol, pretomanid. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Pretomanid regimen associated with hepatotoxicity. Avoid alcohol and hepatotoxic agents, including herbal supplements and drugs other than bedaquiline and linezolid.protamineallopurinol increases effects of protamine by decreasing metabolism. Avoid or Use Alternate Drug.ropeginterferon alfa 2bropeginterferon alfa 2b, allopurinol. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Myelosuppressive agents can produce additive myelosuppression. Avoid use and monitor patients receiving the combination for effects of excessive myelosuppression.theophyllineallopurinol increases levels of theophylline by decreasing metabolism. Avoid or Use Alternate Drug.warfarinallopurinol increases effects of warfarin by anticoagulation. Avoid or Use Alternate Drug.Monitor Closely (15)acalabrutinibacalabrutinib, allopurinol. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration may increase risk of myelosuppressive effects.aluminum hydroxidealuminum hydroxide decreases levels of allopurinol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.amoxicillinallopurinol decreases toxicity of amoxicillin by Other (see comment). Use Caution/Monitor. Comment: Allopurinol may increase potential for allergic or hypersensitivity reactions to amoxicillin.calcium carbonatecalcium carbonate decreases levels of allopurinol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.cyclophosphamideallopurinol increases toxicity of cyclophosphamide by decreasing metabolism. Use Caution/Monitor.dichlorphenamidedichlorphenamide and allopurinol both decrease serum potassium. Use Caution/Monitor.dichlorphenamide, allopurinol. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Both drugs can cause metabolic acidosis.ethambutolethambutol decreases effects of allopurinol by Other (see comment). Use Caution/Monitor. Comment: Hyperuricemia reported with ethambutol and precipitation of gout reported; uric acid lowering agents may be require dosage adjustment.hydroxyureaallopurinol, hydroxyurea. Other (see comment). Use Caution/Monitor. Comment: Combination may increase risk of myelosuppression.mercaptopurineallopurinol increases levels of mercaptopurine by decreasing metabolism. Use Caution/Monitor. Potential for increased myelosuppression.methotrexateallopurinol decreases effects of methotrexate by Other (see comment). Use Caution/Monitor. Comment: Combination may increase risk of myelosuppression.mipomersenmipomersen, allopurinol. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Both drugs have potential to increase hepatic enzymes; monitor LFTs.sodium bicarbonatesodium bicarbonate decreases levels of allopurinol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.sodium citrate/citric acidsodium citrate/citric acid decreases levels of allopurinol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.thioguanineallopurinol, thioguanine. unknown mechanism. Use Caution/Monitor. Potential for increased myelosuppression.valoctocogene roxaparvovecallopurinol and valoctocogene roxaparvovec both increase Other (see comment). Use Caution/Monitor. Medications that may cause hepatotoxicity when combined with valoctogene roxaparvovec may potentiate the risk of elevated liver enzymes. Closely monitor these medications and consider alternative medications in case of potential drug interactions.Minor (3)ampicillinampicillin, allopurinol. Mechanism: unknown. Minor/Significance Unknown. Increased incidence of rash.cyclosporineallopurinol increases levels of cyclosporine by unknown mechanism. Minor/Significance Unknown.tacrolimusallopurinol increases levels of tacrolimus by unknown mechanism. Minor/Significance Unknown.acalabrutinibMonitor Closely (1)acalabrutinib, allopurinol. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration may increase risk of myelosuppressive effects.aluminum hydroxideMonitor Closely (1)aluminum hydroxide decreases levels of allopurinol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.amoxicillinMonitor Closely (1)allopurinol decreases toxicity of amoxicillin by Other (see comment). Use Caution/Monitor. Comment: Allopurinol may increase potential for allergic or hypersensitivity reactions to amoxicillin.ampicillinMinor (1)ampicillin, allopurinol. Mechanism: unknown. Minor/Significance Unknown. Increased incidence of rash.azathioprineSerious - Use Alternative (1)allopurinol increases levels of azathioprine by decreasing metabolism. Avoid or Use Alternate Drug. Increased risk of bone marrow toxicity.benazeprilSerious - Use Alternative (1)benazepril increases toxicity of allopurinol by unspecified interaction mechanism. Avoid or Use Alternate Drug. May increase risk for allergic or hypersensitivity reactions to allopurinol. Monitor for symptoms of hypersensitivity reactions if both drugs must be used together.calcium carbonateMonitor Closely (1)calcium carbonate decreases levels of allopurinol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.captoprilSerious - Use Alternative (2)captopril, allopurinol. Mechanism: unknown. Avoid or Use Alternate Drug. Risk of anaphylaxis, Stevens Johnson syndrome. captopril increases toxicity of allopurinol by Mechanism: unspecified interaction mechanism. Avoid or Use Alternate Drug. May increase risk for allergic or hypersensitivity reactions to allopurinol Monitor for symptoms of hypersensitivty reactions if both drugs must be used together.cyclophosphamideMonitor Closely (1)allopurinol increases toxicity of cyclophosphamide by decreasing metabolism. Use Caution/Monitor.cyclosporineMinor (1)allopurinol increases levels of cyclosporine by unknown mechanism. Minor/Significance Unknown.dichlorphenamideMonitor Closely (2)dichlorphenamide and allopurinol both decrease serum potassium. Use Caution/Monitor. dichlorphenamide, allopurinol. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Both drugs can cause metabolic acidosis.didanosineSerious - Use Alternative (1)allopurinol increases levels of didanosine by unknown mechanism. Contraindicated.enalaprilSerious - Use Alternative (1)enalapril, allopurinol. Mechanism: unknown. Avoid or Use Alternate Drug. Risk of anaphylaxis, Stevens Johnson syndrome.ethambutolMonitor Closely (1)ethambutol decreases effects of allopurinol by Other (see comment). Use Caution/Monitor. Comment: Hyperuricemia reported with ethambutol and precipitation of gout reported; uric acid lowering agents may be require dosage adjustment.hydroxyureaMonitor Closely (1)allopurinol, hydroxyurea. Other (see comment). Use Caution/Monitor. Comment: Combination may increase risk of myelosuppression.mercaptopurineMonitor Closely (1)allopurinol increases levels of mercaptopurine by decreasing metabolism. Use Caution/Monitor. Potential for increased myelosuppression.methotrexateMonitor Closely (1)allopurinol decreases effects of methotrexate by Other (see comment). Use Caution/Monitor. Comment: Combination may increase risk of myelosuppression.mipomersenMonitor Closely (1)mipomersen, allopurinol. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Both drugs have potential to increase hepatic enzymes; monitor LFTs.perindoprilSerious - Use Alternative (1)perindopril, allopurinol. Mechanism: unknown. Avoid or Use Alternate Drug. Risk of anaphylaxis, Stevens Johnson syndrome.pexidartinibSerious - Use Alternative (1)allopurinol and pexidartinib both increase Other (see comment). Avoid or Use Alternate Drug. Pexidartinib can cause hepatotoxicity. Avoid coadministration of pexidartinib with other products know to cause hepatoxicity.pretomanidSerious - Use Alternative (1)allopurinol, pretomanid. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Pretomanid regimen associated with hepatotoxicity. Avoid alcohol and hepatotoxic agents, including herbal supplements and drugs other than bedaquiline and linezolid.protamineSerious - Use Alternative (1)allopurinol increases effects of protamine by decreasing metabolism. Avoid or Use Alternate Drug.ropeginterferon alfa 2bSerious - Use Alternative (1)ropeginterferon alfa 2b, allopurinol. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Myelosuppressive agents can produce additive myelosuppression. Avoid use and monitor patients receiving the combination for effects of excessive myelosuppression.sodium bicarbonateMonitor Closely (1)sodium bicarbonate decreases levels of allopurinol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.sodium citrate/citric acidMonitor Closely (1)sodium citrate/citric acid decreases levels of allopurinol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.tacrolimusMinor (1)allopurinol increases levels of tacrolimus by unknown mechanism. Minor/Significance Unknown.theophyllineSerious - Use Alternative (1)allopurinol increases levels of theophylline by decreasing metabolism. Avoid or Use Alternate Drug.thioguanineMonitor Closely (1)allopurinol, thioguanine. unknown mechanism. Use Caution/Monitor. Potential for increased myelosuppression.valoctocogene roxaparvovecMonitor Closely (1)allopurinol and valoctocogene roxaparvovec both increase Other (see comment). Use Caution/Monitor. Medications that may cause hepatotoxicity when combined with valoctogene roxaparvovec may potentiate the risk of elevated liver enzymes. Closely monitor these medications and consider alternative medications in case of potential drug interactions.warfarinSerious - Use Alternative (1)allopurinol increases effects of warfarin by anticoagulation. Avoid or Use Alternate Drug. 1-10% Rash (1.5%) Nausea (1.3%) Renal failure (1.2%) Vomiting (1.2%) Frequency Not Defined Amblyopia Arthralgias Blood dyscrasias Bronchospasm Cardiovascular abnormalities Cataracts Confusion Decrease in libido Dizziness Ecchymosis Electrolyte abnormalities Epistaxis Foot drop Hematuria Hepatotoxicity Hypotonia Iritis Kidney function abnormality Macular retinitis Malaise Neuritis Pharyngitis Pruritus Skin edema Stevens-Johnson syndrome Sweating Tinnitus Contraindications Patients with a history of severe reaction to any formulation of this drug Cautions Discontinue at first sign of allergic reactions (first sign of rash, vasculitis, or Stevens-Johnson syndrome, drug rash with eosinophilia and systemic symptoms (DRESS) and/or generalized vasculitis, irreversible hepatotoxicity) The HLA-B*58:01 allele is a genetic marker for severe skin reactions indicative of hypersensitivity to allopurinol; patients who carry the HLA-B*58:01 allele are at a higher risk of allopurinol hypersensitivity syndrome (AHS); however, hypersensitivity reactions reported in patients who do not carry this allele; frequency of this allele is higher in individuals of African, Asian (e.g., Han Chinese, Korean, Thai), and Native Hawaiian/Pacific Islander ancestry; prior to starting therapy, consider testing for the HLA-B*58:01 allele in genetically at-risk populations; therapy not recommended in HLA-B*58:01 positive patients unless benefits clearly outweigh risks Myelosuppression reported; use caution when administering other drugs known to cause myelosuppression Hepatotoxicity (reversible) reported Not for treatment of asymptomatic hyperuricemia Use with caution in renal impairment Risk of hypersensitivity increased in patients treated with angiotensin-converting emzyme (ACE) inhibitors When taken with amoxicillin or ampicillin, may increase risk of skin rash During concomitant treatment, reduce dosages of azathioprine and mercaptopurine to 25-33% of usual Occurrence of hypersensitivity reactions may be increased in patients with renal impairment, especially in patients who are receiving thiazide diuretics; reduce dose in patients with impaired renal function Risk of hypersensitivity may increase with concomitant administration of thiazides Maintain fluid intake necessary to yield urine output of at least 2 L/day in adults Pregnancy Available limited published data on allopurinol use in pregnant women do not demonstrate a clear pattern or increase in frequency of adverse developmental outcomes. Among approximately 50 pregnancies described in published literature, 2 infants with major congenital malformations have been reported with following maternal allopurinol exposure. Advise pregnant women of the potential risk to a fetus Animal data Based on findings in animals, this drug may cause fetal harm when administered to a pregnant woman; adverse developmental outcomes described in exposed animals; this drug and its metabolite oxypurinol shown to cross placenta following administration of maternal allopurinol Reproductive studies performed in rats and rabbits at doses up to twenty times usual human dose (5 mg/kg per day) concluded that there was no impaired fertility or harm to fetus due to allopurinol; there is a published report of a study in pregnant mice given 50 or 100 mg/kg allopurinol intraperitoneally on gestation days 10 or 13; there were increased numbers of dead fetuses in dams given 100 mg/kg allopurinol but not in those given 50 mg/kg There were increased numbers of external malformations in fetuses at both doses of allopurinol on gestation