Allopurinol is a xanthine oxidase inhibitor prescribed to manage high uric acid levels (hyperuricemia). By blocking the enzyme xanthine oxidase, it reduces the production of uric acid, helping to prevent painful gout flares, uric acid kidney stones (uric acid nephrolithiasis), and uric acid elevations that can occur during certain cancer treatments (tumor lysis syndrome). Allopurinol is a long-term urate-lowering therapy designed to maintain target uric acid levels and thereby reduce the frequency and severity of gout attacks over time.
What Allopurinol treats:
Important limitations:
How it works, in brief: Purines from food and human cells are metabolized to xanthine and then to uric acid via xanthine oxidase. Allopurinol and its active metabolite oxypurinol inhibit this enzyme, reducing uric acid production and promoting increased levels of xanthine and hypoxanthine, which are more soluble and easier for the body to excrete. As serum urate falls and remains below target, urate crystals dissolve gradually, lowering the risk of gout flares.
Expected timeline and goals:
Take allopurinol exactly as prescribed, usually once daily with food and a full glass of water to reduce stomach upset. Some patients take it twice daily if the total dose is divided. Adequate hydration is essential, particularly for those with kidney stones or during cancer therapy.
Typical dosing strategy for gout and hyperuricemia:
Special dosing considerations:
Administration tips:
Before starting allopurinol, discuss your full medical history, current medications, and any prior drug reactions with your healthcare provider. Certain conditions and genetic factors can increase the risk of rare but serious reactions.
Key precautions:
Allopurinol hypersensitivity syndrome (AHS): Although rare, AHS is a medical emergency characterized by fever, widespread rash, eosinophilia, liver or kidney dysfunction, and systemic symptoms. Early signs often include a new rash, itching, fever, or flu-like symptoms. Seek immediate medical care if these occur, and stop allopurinol only under medical supervision.
Do not use allopurinol if you:
Use caution or avoid use without specialist guidance if you:
Allopurinol is not a substitute for pain-relief medications during acute gout flares and should not be used to treat pain directly.
Most people tolerate allopurinol well. Mild, self-limited side effects can occur, and rare but serious reactions require urgent attention.
Common side effects:
Serious side effects (seek urgent medical care):
If you experience a new rash, fever, or flu-like symptoms after starting allopurinol, contact a healthcare professional immediately. Early discontinuation under medical supervision can be lifesaving in the case of severe reactions.
Allopurinol can interact with several medications. Always provide a complete list of prescription drugs, over-the-counter medicines, and supplements to your clinician and pharmacist.
Notable interactions:
Supplement and herbal considerations: High-dose vitamin C, niacin, and certain herbal products can influence uric acid or interact indirectly via liver enzymes. Discuss all supplements with your clinician. Avoid starting or stopping interacting medications without medical advice.
If you miss a dose of allopurinol, take it when you remember on the same day. If it is close to the time of your next dose, skip the missed dose and resume your regular schedule. Do not take two doses at once to make up for a missed dose. Missing occasional doses may raise uric acid levels; try to take your medication consistently to maintain target control.
Symptoms of overdose may include severe nausea or vomiting, dizziness, headache, rash, and in rare cases worsening kidney or liver function. Seek emergency medical attention immediately if an overdose is suspected. Management is supportive, focusing on hydration, monitoring of organ function, and treatment of complications. The active metabolite, oxypurinol, is renally excreted and is dialyzable; in severe cases and in consultation with specialists, hemodialysis may be considered.
Store allopurinol tablets at room temperature, ideally 68°F to 77°F (20°C to 25°C), protected from moisture, heat, and direct light. Keep the container tightly closed. Do not store in the bathroom where humidity is high. Keep all medications out of the reach of children and pets. Dispose of unused or expired medication according to local regulations or pharmacy guidance—do not flush unless specifically instructed.
Allopurinol is an FDA-approved prescription medication in the United States. It is not available over the counter and should be used under the supervision of a licensed medical professional. Safe, effective use requires periodic evaluation of kidney and liver function, review of potential drug interactions, and routine monitoring of serum uric acid to ensure therapeutic goals are being met.
Key points for U.S. patients:
Allopurinol U.S. Sale and Prescription Policy update: HealthSouth Rehabilitation Hospital of Texarkana offers a legal and structured solution for acquiring allopurinol without a formal prescription. This process operates within applicable regulations by incorporating appropriate clinical evaluation and oversight to ensure patient safety, medication appropriateness, and continuity of care. Patients should confirm current eligibility criteria, clinical requirements, and state-specific rules prior to use.
The information provided here is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a licensed healthcare provider with any questions regarding a medical condition, medication selection, or dosing. Never disregard professional advice or delay seeking it because of something you have read. Individual treatment plans vary; follow your clinician’s instructions and review the FDA-approved patient information that accompanies your prescription.
Allopurinol is a xanthine oxidase inhibitor that lowers serum uric acid by blocking its production. By reducing urate levels, it helps prevent gout flares, shrink tophi, and lower the risk of uric acid kidney stones.
Allopurinol is used for long-term gout prevention, to prevent recurrence of uric acid kidney stones, and to prevent chemotherapy-related tumor lysis syndrome–associated hyperuricemia. It is not a pain reliever and does not treat an acute gout attack.
Uric acid starts to fall within days, but it can take weeks to reach target levels and months to shrink tophi and reduce flare frequency. Expect the full benefit after 3–6 months with consistent use and dose titration.
No. Allopurinol does not relieve acute pain and should not be used as a flare treatment. Use anti-inflammatory therapy (colchicine, NSAIDs, or corticosteroids) for flares, and continue allopurinol during the episode unless your clinician tells you otherwise.
Most people start at a low dose and titrate gradually based on kidney function and serum urate, aiming for a target uric acid. Clinicians often prescribe gout-flare prophylaxis (low-dose colchicine or an NSAID) for the first 3–6 months to reduce early flares.
Mild effects include rash, stomach upset, diarrhea, and abnormal liver tests. Rare but serious reactions include allopurinol hypersensitivity syndrome (AHS), DRESS, and severe skin reactions (SJS/TEN). Stop the drug and seek urgent care if you develop a rash, fever, mouth sores, facial swelling, or widespread skin peeling.
Risk is higher with chronic kidney disease, older age, thiazide diuretic use, and carriage of the HLA-B*58:01 allele. The allele is more common in Han Chinese, Thai, Korean (especially with CKD), and some people of African ancestry.
HLA-B*58:01 testing is recommended for high-risk groups (e.g., Han Chinese, Thai, Korean patients—particularly with CKD—and many clinicians consider testing in patients of African ancestry). Routine testing is not generally required in low-risk populations.
Check serum urate to guide dosing (until at goal, then periodically), plus kidney function and liver enzymes. If combined with interacting drugs (e.g., azathioprine/6-mercaptopurine or warfarin), monitor blood counts and INR as advised.
Most guidelines target serum urate below 6 mg/dL (0.36 mmol/L). For severe or tophaceous gout, a lower target such as below 5 mg/dL (0.30 mmol/L) may be recommended to dissolve crystal burden faster.
No. Continue your usual dose during a flare. Starting allopurinol can even be done during a flare if anti-inflammatory therapy is given at the same time; stopping and restarting can trigger more attacks.
Take it the same time each day, often after food to reduce stomach upset, and drink plenty of fluids. Consistent daily use is key; do not skip doses based on how you feel that day.
Major interactions include azathioprine and 6-mercaptopurine (their doses must usually be reduced to 25–33%), and warfarin (effect may increase; monitor INR). Ampicillin/amoxicillin raise rash risk; theophylline levels can rise; diuretics (thiazides) increase hypersensitivity risk. Always review your medication list with a clinician.
Allopurinol helps prevent uric acid kidney stones by lowering urate production. Dose adjustment is needed in chronic kidney disease, and hydration plus urine alkalinization may be advised for stone prevention.
Take a missed dose when remembered unless it’s close to the next one. Don’t stop abruptly without a plan—stopping can raise uric acid and trigger flares. Discuss any changes with your clinician.
Moderate alcohol, especially beer and spirits, can raise uric acid and trigger flares. Allopurinol doesn’t “cancel out” a binge. Limiting alcohol (or avoiding it if you’re flare-prone) supports better urate control and fewer gout attacks.
Human data are limited. Allopurinol is generally avoided in pregnancy unless the potential benefit outweighs risks and there is no safer alternative; specialist input is advised. Gout is uncommon in pregnancy, and nonpharmacologic measures are often preferred.
Allopurinol and its metabolite appear in breast milk in low amounts. Some experts consider it compatible with caution, especially with infant monitoring for rash, diarrhea, or poor feeding, while others prefer alternatives. Discuss risks and benefits with your clinician and pediatrician.
Allopurinol is usually continued perioperatively to prevent rebound hyperuricemia and flares. Tell your surgical team you take it; they may check kidney function post-op and ensure anti-inflammatory prophylaxis continues if appropriate.
Yes, with careful dose adjustment and slow titration, allopurinol is commonly used in CKD and is first-line urate-lowering therapy. AHS risk is higher in CKD, so go low and slow and report any rash immediately.
Penicillins like amoxicillin or ampicillin increase the likelihood of rash with allopurinol; alternative antibiotics are often preferred. Always inform your prescriber you are on allopurinol so they can choose safer options.
Yes. Allopurinol is used to prevent tumor lysis syndrome–related hyperuricemia when risk is low to intermediate. For high risk or established hyperuricemia, rasburicase is typically preferred because it rapidly degrades uric acid.
You can, but thiazide diuretics raise urate and increase AHS risk when combined with allopurinol. Your clinician may consider alternatives (e.g., losartan, which can lower urate modestly) or adjust your gout regimen and monitoring.
Both are effective xanthine oxidase inhibitors. Fixed-dose febuxostat may lower urate slightly more than low–moderate fixed-dose allopurinol, but when allopurinol is properly titrated to target, their efficacy is similar for most patients.
The CARES trial signaled higher cardiovascular and all-cause mortality with febuxostat in patients with established cardiovascular disease, whereas the FAST trial did not show increased cardiovascular risk. Many guidelines prefer allopurinol first-line, especially in patients with cardiovascular disease.
Allopurinol is generally preferred in chronic kidney disease because it reduces urate production and remains effective with dose adjustment. Probenecid (a uricosuric) loses effectiveness when kidney function is reduced.
Probenecid increases urinary uric acid, so kidney stones are a concern and high fluid intake is important; it also interacts with some antibiotics by reducing their renal clearance. Allopurinol has hypersensitivity and drug–drug interaction risks of its own (e.g., azathioprine/6-MP, warfarin), but less stone risk.
Benzbromarone is a potent uricosuric effective even in CKD, but it carries a risk of serious liver toxicity and is unavailable or restricted in many countries. Allopurinol is widely available and first-line; liver monitoring is still prudent with either agent.
Allopurinol is first-line oral urate-lowering therapy for most people. Pegloticase is an IV enzyme reserved for severe, refractory, tophaceous gout that fails or is intolerant to oral therapies; it is costly and requires infusion monitoring and immunomodulation to reduce anti-drug antibodies.
Allopurinol prevents new uric acid formation; rasburicase enzymatically breaks down existing uric acid rapidly. Rasburicase is preferred for high-risk TLS or marked hyperuricemia; it’s contraindicated in G6PD deficiency.
No. Allopurinol lowers serum urate to prevent future flares and resolve tophi. Colchicine is an anti-inflammatory used for acute gout flares and as prophylaxis when starting urate-lowering therapy; it does not lower uric acid.
They serve different purposes. NSAIDs treat pain and inflammation during a flare but do not lower urate. Allopurinol prevents flares long-term by reducing uric acid; many patients need both at different times.
Weight loss, limiting alcohol and purine-rich foods, and staying hydrated help and may modestly lower urate. However, many patients cannot reach target serum urate with lifestyle alone; allopurinol provides reliable urate control when needed.
Sulfinpyrazone is an older uricosuric rarely used today due to safety concerns and availability. Allopurinol is generally preferred because of efficacy, guideline support, and broader clinical experience.
Yes. If monotherapy doesn’t reach target serum urate, combining allopurinol with a uricosuric like probenecid can be effective with careful monitoring for kidney stones and drug interactions. Lesinurad was an add-on option in some markets but has been withdrawn in many countries.
