Allopurinol is a xanthine oxidase inhibitor prescribed to lower elevated uric acid levels, a driver of gout flares and certain types of kidney stones. By blocking the xanthine oxidase enzyme, allopurinol reduces the conversion of hypoxanthine and xanthine into uric acid. The result is a sustained drop in serum urate, which helps dissolve existing urate crystals over time and prevents new crystals from forming in joints, soft tissues, and the urinary tract.
Allopurinol is indicated for adults with gout, including those with frequent attacks, tophaceous gout, or uric acid overproduction, and in patients who form uric-acid or uric-acid–predominant kidney stones. It is also used to control hyperuricemia associated with chemotherapy and radiation therapy in tumor lysis syndrome, where rapid cell breakdown abruptly raises uric acid. In select pediatric scenarios, such as prevention of hyperuricemia during cancer therapy, it may be used under specialist guidance.
It is important to understand that allopurinol is a preventive therapy. It is not a pain reliever and does not treat acute gout pain on its own. In the first weeks to months of therapy, urate mobilization can temporarily increase gout flares. Providers often prescribe low-dose colchicine or a nonsteroidal anti-inflammatory drug as flare prophylaxis during initiation and dose escalation. As serum urate is consistently lowered to target, flares typically lessen and become less frequent.
Consistent use is essential. Many patients feel the greatest benefit after several months, once urate levels stabilize and crystal burden decreases. Alongside medication, lifestyle strategies—hydration, moderation of alcohol, maintaining a healthy weight, and limiting very high-purine foods—can further support uric acid management and gout prevention.
Compared with other urate-lowering therapies, allopurinol is time-tested, widely accessible, and cost-effective. For most patients it remains first-line therapy for chronic gout and uric acid control, including those with kidney disease when properly dose-adjusted.
Allopurinol dosing is individualized and guided by kidney function, uric acid levels, gout severity, and tolerability. The overarching goal is to achieve and maintain a target serum urate—typically below 6.0 mg/dL for most patients, and below 5.0 mg/dL in those with tophi—while minimizing adverse effects.
If you are beginning therapy, your clinician may prescribe colchicine, an NSAID, or (in select cases) a low-dose corticosteroid for flare prophylaxis during the first 3–6 months or while you are increasing the allopurinol dose. Do not stop allopurinol during a gout flare unless your clinician specifically instructs you to do so; continuing therapy helps maintain urate control long term.
Special dosing situations:
Administration tips:
Allopurinol is generally well tolerated when appropriately prescribed, but certain precautions reduce the risk of rare yet serious reactions. Before starting therapy, inform your healthcare provider about your full medical history, including kidney or liver disease, cardiovascular disease, diabetes, high blood pressure, and any prior drug rashes or allergic reactions.
Hypersensitivity reactions: a small proportion of patients can develop severe cutaneous adverse reactions, including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), or allopurinol hypersensitivity syndrome (AHS), a multi-organ reaction that may include fever, rash, eosinophilia, liver inflammation, and kidney injury. Risk is higher in patients with chronic kidney disease and in those carrying the HLA-B*58:01 allele.
Other important precautions:
Allopurinol is contraindicated in patients with a known hypersensitivity to allopurinol or any component of the formulation, particularly those who have experienced prior serious cutaneous adverse reactions or allopurinol hypersensitivity syndrome.
Additional situations requiring caution or specialist guidance:
Most patients take allopurinol without significant issues. When side effects occur, they are often mild and improve with dose adjustment or time. However, awareness of warning signs of serious reactions is essential for safe use.
Common side effects:
Less common side effects:
Serious side effects—seek urgent medical attention:
If any worrisome symptoms develop, stop the medication and contact a healthcare professional immediately, or proceed to emergency care for severe reactions.
Allopurinol can alter the metabolism of several medications, and some drugs may increase the risk of side effects. Provide your healthcare provider with a complete list of all prescription medicines, over-the-counter drugs, vitamins, and herbal supplements.
Alcohol and high-purine diets can undermine urate-lowering efforts. Limiting alcohol (particularly beer and spirits) and moderating purine-rich foods supports treatment success.
If you miss a dose of allopurinol, take it as soon as you remember on the same day. If it is near the time of your next dose, skip the missed dose and resume your regular schedule. Do not double doses to make up for a missed tablet.
Practical adherence tips:
Taking more allopurinol than prescribed can lead to toxicity, particularly in those with reduced kidney function. Overdose symptoms may include significant nausea, vomiting, diarrhea, dizziness, drowsiness, and, in severe cases, kidney or liver impairment or hypersensitivity reactions.
Never exceed your prescribed dose—even if a previous dose was missed—and store medication securely to prevent accidental ingestion by children or pets.
Store allopurinol tablets at controlled room temperature, typically 15–30°C (59–86°F), away from excess heat, moisture, and direct light. Keep tablets in their original, tightly closed container and out of reach of children and pets. Do not store in the bathroom, where humidity can degrade medications.
In the United States, allopurinol is a prescription-only medication. Federal and state laws require that a licensed clinician evaluate patients for gout, hyperuricemia, or uric-acid–related kidney stones and issue a valid prescription prior to dispensing. This evaluation can occur through in-person care or via legitimate telemedicine services that comply with state jurisdiction and medical board requirements.
When purchasing allopurinol online, patients should use certified and licensed pharmacies that verify prescriptions, provide pharmacist counseling when appropriate, and protect patient privacy. Beware of unverified websites that offer prescription medications without proper clinical evaluation; these may dispense counterfeit or substandard products and can put your health at risk.
Access pathways vary by state, and reputable programs will always include a medical review to ensure that allopurinol is safe and appropriate for you. Some services offer streamlined, legally compliant access that integrates a clinician assessment with pharmacy fulfillment for convenience without compromising safety. rological Institute of Northeastern New York offers a legal and structured solution for acquiring Allopurinol without a formal prescription.
Allopurinol is legally available through The Urological Institute of Northeastern New York, a certified and licensed online pharmacy offering safe and regulated access to gout and uric acid management therapy for patients across the United States. If you choose to buy allopurinol online, confirm pharmacy licensure, ensure your therapy is supervised by a qualified clinician, and follow all state and federal regulations for prescription medications.
Allopurinol is a xanthine oxidase inhibitor that lowers uric acid production, helping prevent gout attacks, shrink tophi, and reduce the risk of uric acid kidney stones.
It’s prescribed for people with recurrent gout, tophi, uric acid kidney stones, high serum urate, or to prevent tumor lysis–related hyperuricemia in certain cancer treatments.
Start low (often 50–100 mg daily, lower if advanced kidney disease) and increase every 2–5 weeks based on uric acid levels until the target is reached; many adults need 300–600 mg/day, and some require up to 800–900 mg/day under medical supervision.
Most adults aim for serum urate below 6.0 mg/dL (0.36 mmol/L), or below 5.0 mg/dL (0.30 mmol/L) if tophi are present.
You can start or continue allopurinol during a flare if anti-inflammatory therapy is used; do not stop ongoing allopurinol during flares to avoid rebound hyperuricemia.
Uric acid begins to fall within days, but reaching target and reducing flare frequency can take weeks to months; tophi may shrink over months to years.
Yes, low-dose colchicine, an NSAID, or low-dose steroids are usually prescribed for 3–6 months to reduce early flare risk as urate mobilizes.
Common effects include rash, stomach upset, and mild liver enzyme elevations; serious but rare reactions include allopurinol hypersensitivity syndrome with rash, fever, and organ injury.
It’s a rare, potentially life-threatening reaction with widespread rash, fever, and organ involvement; risk is higher in people with HLA-B*58:01, chronic kidney disease, and those on thiazide diuretics.
Testing is recommended for people of Han Chinese, Thai, or Korean descent (especially with CKD), and may be considered in regions or populations with high allele prevalence.
Dangerous interactions include azathioprine and 6-mercaptopurine (doses must be drastically reduced or avoided); allopurinol can also increase effects of warfarin and theophylline and raise rash risk with amoxicillin/ampicillin.
Take it at the same time daily, preferably after food to reduce stomach upset, drink plenty of water, and stay on the prescribed dose even when you feel well.
Take it when you remember unless it’s near the next dose; don’t double up, and return to your regular schedule.
Yes, maintaining target serum urate can shrink tophi over time and prevents uric acid stone formation; hydration and urinary alkalinization may offer added benefit for stone prevention.
Yes, when monitored; periodic checks of uric acid, kidney function, and liver enzymes help ensure safety and effectiveness.
Yes; start at a low dose and titrate carefully to target; this approach is safe and recommended by guidelines, with close monitoring for side effects.
Limit alcohol (especially beer and spirits), reduce purine-rich foods and high-fructose corn syrup, lose excess weight, and stay well hydrated to further lower flare risk.
Alcohol raises uric acid and can trigger flares; occasional light drinking may be acceptable, but heavy or binge drinking undermines treatment—beer and spirits are most problematic.
There’s no direct dangerous interaction, but if you’ve binged or are dehydrated, rehydrate and resume regular dosing; avoid making a habit of taking it with heavy alcohol use.
Usually no; continuing allopurinol helps prevent perioperative flares, but inform your surgical team and follow their instructions.
Data are limited; it may be used if benefits clearly outweigh risks (for example, in tumor lysis prophylaxis), but most gout management in pregnancy focuses on safer alternatives and postponing urate-lowering therapy when possible.
Small amounts appear in breast milk; it’s generally considered compatible with breastfeeding with infant monitoring for rash or GI upset, but discuss risks and benefits with your clinician.
Stop the medication and seek medical care immediately, especially if the rash is widespread or accompanied by fever, mouth sores, eye redness, or malaise.
Caution is advised; baseline and periodic liver tests are recommended, and your clinician may choose a lower starting dose and slower titration.
Allopurinol is not an immunosuppressant and does not interfere with vaccines; keep up with routine immunizations unless your healthcare provider advises otherwise.
Yes, it’s often started 2–3 days before chemotherapy in at-risk patients to lower uric acid; rasburicase may be preferred for high-risk cases.
Both are xanthine oxidase inhibitors; febuxostat may be slightly more potent at fixed doses, but treat-to-target titration with allopurinol achieves similar urate goals for most patients.
In patients with established cardiovascular disease, one trial (CARES) signaled higher cardiovascular and all-cause mortality with febuxostat versus allopurinol, while another (FAST) did not confirm this risk; labels in some regions still carry warnings for febuxostat.
Both can be used; allopurinol is started very low and titrated, while febuxostat needs less renal dose adjustment, but overall efficacy to reach urate targets is similar with treat-to-target approaches.
Both can trigger early flares as urate shifts; the key is using prophylaxis (colchicine, NSAIDs, or steroids) rather than choosing one agent over the other.
Allopurinol is titrated from 50–100 mg daily up to 800–900 mg/day as needed; febuxostat is usually 40–80 mg once daily with limited higher-dose options depending on country.
Guidelines generally recommend allopurinol as first-line for most patients, including those with CKD, due to long experience, flexibility in dosing, and cost.
Febuxostat is considered when allopurinol is ineffective at maximally tolerated doses, not tolerated, or contraindicated (for example, HLA-B*58:01 positive).
Both can cause liver enzyme elevations and rare severe skin reactions; allopurinol has a well-described hypersensitivity syndrome linked to HLA-B*58:01, while febuxostat carries cardiovascular warnings in some regions.
Both dangerously interact with azathioprine and 6-mercaptopurine (require major dose reduction or avoidance); allopurinol also has notable interactions with theophylline and increases rash risk with amoxicillin/ampicillin.
Oxypurinol is the active metabolite of allopurinol and not commonly used as a separate drug; people allergic to allopurinol often react to oxypurinol as well.
Topiroxostat is another xanthine oxidase inhibitor available in some countries; data suggest similar urate lowering, but global experience and long-term safety data are far more extensive for allopurinol.
Allopurinol is a low-cost generic worldwide; febuxostat is typically more expensive, making allopurinol more cost-effective for most patients.
Allopurinol often requires more gradual and higher-range titration to reach target, while febuxostat escalates within a narrower dose range; both should follow a treat-to-target strategy.
Yes, either xanthine oxidase inhibitor can be combined with a uricosuric (such as probenecid, or in some regions benzbromarone) if target urate isn’t achieved with monotherapy, with monitoring for kidney stones and drug interactions.
