{"ok":true,"entry":{"slug":"allopurinol","kind":"medication","name":"allopurinol","aliases":["Zyloric","Zyloprim"],"brands_sg":["Zyloric","Apo-Allopurinol","YSP Allopurinol","GP-Allopurinol"],"class":"xanthine oxidase inhibitor","tags":["other"],"use_for":"lowering uric acid to prevent gout attacks and urate stones","use_after":"nhs: usually once a day · started after an attack settles","use_duration":null,"take_with":"water · with or after food · healthhub: 2–3 litres a day","pros":["nhs: fewer gout attacks, less joint damage over time","healthhub: also used for uric acid (urate) stones","nhs: one tablet a day, usually 100mg to 300mg"],"cons":["more gout attacks in the first months (nhs, healthhub)","healthhub: rare severe skin reactions (sjs, ten, dress)","nausea, being sick and stomach upset are common (nhs)"],"dose_note":"the us allopurinol label states, for gout with normal kidney function: 'initial dosage is 100 mg orally daily. increase by 100 mg weekly increments until serum uric acid of 6 mg/dl or less is reached (maximum 800 mg daily)'. nhs describes 100mg to 300mg tablets daily and says a doctor 'may increase your dose (up to 900mg daily in severe cases)' — the two label maximums differ, 800 mg on the us label and 900mg on the nhs page. a lower dose applies in kidney or liver disease. the prescriber sets the dose.","dosage":null,"ul_status":null,"sg_class":"prescription-only","cautions":["nhs: han chinese, thai or korean origin — higher risk of a severe skin reaction","healthhub: kidney problems — a hla-b*5801 gene test may come first","liver problems or thyroid problems (nhs)","nhs: an ongoing gout attack — usually started after it has settled"],"clashes":[{"src":["hh_allo_avoid","fda_allo_int"],"note":"healthhub lists both as medicines to tell the doctor about · us label: reduce the mercaptopurine or azathioprine dose","with":"azathioprine or mercaptopurine"},{"src":["hh_allo_avoid","nhs_allo_other"],"note":"healthhub names warfarin · nhs: can affect each other and increase the chance of side effects","with":"warfarin, other anticoagulants and aspirin"},{"src":["fda_allo_int","nhs_allo_other"],"note":"us label: may increase the risk of serious skin reactions · nhs asks about any antibiotics","with":"ampicillin and amoxicillin"},{"src":["fda_allo_int","nhs_allo_other"],"note":"us label: thiazides may increase skin-reaction risk, more so with kidney impairment · nhs lists both groups","with":"thiazide diuretics and ace inhibitors (e.g. furosemide, enalapril, ramipril)"},{"src":["nhs_allo_antacid"],"note":"nhs describes a 3-hour gap between the aluminium hydroxide and the allopurinol dose","with":"aluminium hydroxide antacids (maalox, mucogel)"}],"sources":[{"id":"hsa_register_allo","url":"https://data.gov.sg/datasets/d_767279312753558cbf19d48344577084/view","label":"HSA — Listing of Registered Therapeutic Products (data.gov.sg open dataset, 5,511 rows, full dataset pulled once via datastore_search and filtered locally)","quote":"9 registered allopurinol products, every one Forensicclassification 'Prescription Only': SIN06060P/SIN06061P ZYLORIC TABLET 100 mg and 300MG, SIN06247P/SIN06248P APO-ALLOPURINOL, SIN07051P/SIN17004P YSP ALLOPURINOL, SIN17232P GP-ALLOPURINOL, SIN05804P and SIN06219P plain ALLOPURINOL TABLET — all tablets","accessed":"2026-08-27"},{"id":"nhs_allo_about","url":"https://www.nhs.uk/medicines/allopurinol/about-allopurinol/","label":"NHS Medicines A-Z — Allopurinol (brand names: Zyloric, Uricto), 'About allopurinol', page last reviewed 23 January 2023","quote":"Allopurinol is a medicine used to lower levels of uric acid in your blood … These crystals can form around your joints, which cause the swollen and painful symptoms of gout … only available on prescription.","accessed":"2026-08-27"},{"id":"nhs_allo_key","url":"https://www.nhs.uk/medicines/allopurinol/about-allopurinol/","label":"NHS Medicines A-Z — Allopurinol, 'About allopurinol' key facts","quote":"During the first few months of treatment, as allopurinol starts to work, you may get more gout attacks … Usually, you'll start allopurinol after an acute attack of gout has completely settled.","accessed":"2026-08-27"},{"id":"nhs_allo_how","url":"https://www.nhs.uk/medicines/allopurinol/how-and-when-to-take-allopurinol/","label":"NHS Medicines A-Z — Allopurinol, 'How and when to take allopurinol'","quote":"Allopurinol comes as 100mg to 300mg tablets that you take every day … your doctor may increase your dose (up to 900mg daily in severe cases) … Swallow your allopurinol tablet with water, ideally after food.","accessed":"2026-08-27"},{"id":"nhs_allo_who","url":"https://www.nhs.uk/medicines/allopurinol/who-can-and-cannot-take-allopurinol/","label":"NHS Medicines A-Z — Allopurinol, 'Who can and cannot take allopurinol'","quote":"tell your pharmacist or doctor before taking it if you: … are of Han Chinese, Thai or Korean origin … have problems with your liver or kidneys … currently have an attack of gout … have thyroid problems","accessed":"2026-08-27"},{"id":"nhs_allo_se","url":"https://www.nhs.uk/medicines/allopurinol/side-effects-of-allopurinol/","label":"NHS Medicines A-Z — Allopurinol, 'Side effects of allopurinol': Stevens-Johnson syndrome","quote":"Stevens-Johnson syndrome is a rare side effect of allopurinol. It causes flu-like symptoms, followed by a red or purple rash that spreads and forms blisters … more likely to happen in the first 8 weeks","accessed":"2026-08-27"},{"id":"nhs_allo_other","url":"https://www.nhs.uk/medicines/allopurinol/taking-allopurinol-with-other-medicines-and-herbal-supplements/","label":"NHS Medicines A-Z — Allopurinol, 'Taking allopurinol with other medicines and herbal supplements'","quote":"aspirin or medicines used to help prevent blood clots (anticoagulants), such as warfarin; any antibiotics; medicines used to reduce your immune response; tablets that make you pee more (diuretics) such as furosemide or ACE inhibitors","accessed":"2026-08-27"},{"id":"nhs_allo_antacid","url":"https://www.nhs.uk/medicines/allopurinol/taking-allopurinol-with-other-medicines-and-herbal-supplements/","label":"NHS Medicines A-Z — Allopurinol, interactions: aluminium hydroxide antacids","quote":"If you take aluminium hydroxide (found in some antacids such as Maalox and Mucogel), leave a 3-hour gap between the aluminium hydroxide and your allopurinol dose.","accessed":"2026-08-27"},{"id":"hh_allopurinol","url":"https://www.healthhub.sg/medication-devices-and-treatment/medications/allopurinol","label":"HealthHub (MOH Singapore / National Medication Information workgroup) — Allopurinol leaflet, article last reviewed 4 June 2026: uses","quote":"Allopurinol is used to prevent gout … Allopurinol reduces the production of uric acid, thus lowering the uric acid levels in the body. Allopurinol is also used in the treatment of uric acid stones","accessed":"2026-08-27"},{"id":"hh_allo_admin","url":"https://www.healthhub.sg/medication-devices-and-treatment/medications/allopurinol","label":"HealthHub — Allopurinol leaflet: how it is taken and fluid intake","quote":"This medication should be taken with or after food to reduce stomach upset. Take this medication with plenty of water … Drink enough water (2-3 litres of water a day) unless your doctor has advised you to restrict fluid intake.","accessed":"2026-08-27"},{"id":"hh_allo_se","url":"https://www.healthhub.sg/medication-devices-and-treatment/medications/allopurinol","label":"HealthHub — Allopurinol leaflet: common side effects and early gout flares","quote":"Diarrhea … Upset stomach … When allopurinol is started for gout prevention, the chances of having gout attacks may be higher initially.","accessed":"2026-08-27"},{"id":"hh_allo_skin","url":"https://www.healthhub.sg/medication-devices-and-treatment/medications/allopurinol","label":"HealthHub — Allopurinol leaflet: rare but serious skin reactions (links to the HSA consumer guide 'Safe use of allopurinol')","quote":"very rarely, a bad skin reaction known as Stevens-Johnson syndrome (SJS), Toxic epidermal necrolysis (TENs) or Drug reaction with eosinophilia and systematic symptoms (DRESS) may happen. This can cause serious health problems that may sometimes be fatal.","accessed":"2026-08-27"},{"id":"hh_allo_hla","url":"https://www.healthhub.sg/medication-devices-and-treatment/medications/allopurinol","label":"HealthHub — Allopurinol leaflet: HLA-B*5801 gene testing before starting","quote":"Your doctor may conduct a gene testing before starting this medication as individuals with a specific gene type (HLA-B*5801) or poor kidney function may be more likely to suffer serious skin reactions.","accessed":"2026-08-27"},{"id":"hh_allo_avoid","url":"https://www.healthhub.sg/medication-devices-and-treatment/medications/allopurinol","label":"HealthHub — Allopurinol leaflet: food and medicines to tell the doctor about","quote":"What food or medication should I avoid when I take or use this medication? Inform your doctor if you are taking: Warfarin, Azathioprine, Mercaptopurine","accessed":"2026-08-27"},{"id":"fda_allopurinol","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=005048dd-844f-468c-bf56-1a09727e3477","label":"FDA DailyMed SPL — Allopurinol tablets, Highlights of Prescribing Information (label effective 8 Jul 2024), read via the openFDA drug-label API","quote":"Patients with normal kidney function: Initial dosage is 100 mg orally daily. Increase by 100 mg weekly increments until serum uric acid of 6 mg/dl or less is reached (maximum 800 mg daily).","accessed":"2026-08-27"},{"id":"fda_allo_int","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=005048dd-844f-468c-bf56-1a09727e3477","label":"FDA DailyMed SPL — Allopurinol tablets, section 7 Drug Interactions","quote":"The following drugs may increase the risk of serious skin reactions: bendamustine, thiazide diuretics, ampicillin and amoxicillin. Capecitabine: Avoid concomitant use. Mercaptopurine or Azathioprine: Reduce mercaptopurine or azathioprine dose as recommended in the respective prescribing information.","accessed":"2026-08-27"},{"id":"fda_allo_hla","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=005048dd-844f-468c-bf56-1a09727e3477","label":"FDA DailyMed SPL — Allopurinol tablets, section 5.1 Skin Rash and Hypersensitivity","quote":"The HLA-B*58:01 allele is a genetic marker for severe skin reactions … The frequency of this allele is higher in individuals of African, Asian (e.g., Han Chinese, Korean, Thai), and Native Hawaiian/Pacific Islander ancestry","accessed":"2026-08-27"}],"brand_certs":null,"updated_at":"2026-08-29T16:16:10.48466+08:00"},"disclaimer":"kozen-x is not a medical device and does not give medical advice. it lists what published sources have written down. absence of a record is not the same as safe."}