Xanthine Oxidase Inhibitor — Urate-Lowering Therapy Pregnancy: Febuxostat should not be used during pregnancy — data on a very limited number of exposed pregnancies have not indicated adverse effects and animal studies do not indicate harm, but the potential risk to humans is unknown. It should also not be used while breast-feeding (excretion in human milk unknown; animal studies show excretion in milk and impaired development of suckling pups). The effect on human fertility is unknown.

Febuxostat (Rheumatology — Gout)

Brand names: Adenuric

Febuxostat is an oral urate-lowering agent used in rheumatology for the long-term management of chronic gout with hyperuricaemia, particularly where allopurinol is not tolerated or is contraindicated.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 80 mg

Route: Oral — taken by mouth, with or without food

Frequency: Once daily

Max: 120 mg once daily (the highest dose in the UK SPC; for gout this may be considered if serum uric acid remains > 6 mg/dL (357 micromol/L) after 2–4 weeks, and 120 mg once daily is the recommended dose for tumour lysis syndrome)

GOUT (the indication for this page): recommended oral dose 80 mg once daily without regard to food. If serum uric acid is > 6 mg/dL (357 micromol/L) after 2–4 weeks, 120 mg once daily may be considered; the SPC states febuxostat works sufficiently quickly to allow retesting of serum uric acid after 2 weeks. The therapeutic target is to decrease and maintain serum uric acid below 6 mg/dL (357 micromol/L). Gout flare prophylaxis of at least 6 months is recommended. TUMOUR LYSIS SYNDROME (separate licensed indication): 120 mg once daily without regard to food, started two days before the beginning of cytotoxic therapy and continued for a minimum of 7 days; treatment may be prolonged up to 9 days according to chemotherapy duration as per clinical judgment. Patients undergoing chemotherapy at intermediate to high risk of TLS should be under cardiac monitoring as clinically appropriate. ELDERLY: no dose adjustment required. HEPATIC IMPAIRMENT: for gout the recommended dose in mild hepatic impairment is 80 mg; limited information is available in moderate impairment; efficacy and safety have not been studied in severe hepatic impairment (Child Pugh Class C). PAEDIATRIC: the safety and efficacy of febuxostat in children below the age of 18 years have not been established and no data are available — no paediatric dose is stated in the source. CARDIOVASCULAR CAUTION (§4.4): in patients with pre-existing major cardiovascular disease (e.g. myocardial infarction, stroke, unstable angina) a higher number of fatal cardiovascular events was observed with febuxostat than with allopurinol in the CARES study; treat such patients cautiously and monitor regularly, and titrate appropriately to minimise gout flares on initiation. Stop febuxostat immediately and never re-start it if a serious allergic/hypersensitivity reaction (including Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS or anaphylaxis) occurs. US LABELLING DIFFERS and is NOT the basis of the dose above: the US prescribing information in this bundle gives a recommended starting dosage of 40 mg once daily, increased to 80 mg once daily if serum uric acid is not below 6 mg/dL after two weeks, and limits the dosage to 40 mg once daily in severe renal impairment. SOURCE: UK SPC (eMC), Adenuric 120 mg film-coated tablets, §4.2 — https://www.medicines.org.uk/emc/product/1925/smpc

Dose adjustments

Renal

No dose adjustment is necessary in patients with mild or moderate renal impairment. Efficacy and safety have not been fully evaluated in patients with severe renal impairment (creatinine clearance < 30 mL/min). Note the US prescribing information in this bundle instead limits the dosage to 40 mg once daily in severe renal impairment.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients (UK SPC §4.3)
Concurrent treatment with azathioprine or mercaptopurine — stated as a contraindication in the US prescribing information in this bundle (UK SPC §4.5 was not retrieved; clinician to confirm against the UK SPC)

Side effects

Gout flares (common) — may occur after initiation as urate is mobilised from tissue deposits; flare prophylaxis for at least 6 months is recommended
Liver function abnormalities
Diarrhoea and nausea (common)
Headache and dizziness (common); dyspnoea (common)
Rash and pruritus; oedema and fatigue. Rare but serious: hypersensitivity reactions including Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS and anaphylactic reaction/shock, and rare events of sudden cardiac death (post-marketing)

Interactions

Azathioprine and mercaptopurine — febuxostat is a xanthine oxidase (XO) inhibitor; co-administration increases plasma concentrations of these XO substrates and may result in severe toxicity. Contraindicated in the US label (US PI §7; UK SPC §4.5 not retrieved in this bundle)
Theophylline — febuxostat altered the metabolism of theophylline (an XO substrate) in a healthy-volunteer study; use with caution when co-administered (US PI §7.1)
Cytotoxic chemotherapy — no drug interaction studies have been conducted and no data are available on the safety of febuxostat during cytotoxic chemotherapy (US PI §7.2)

Clinical monograph

How it works

It is a selective non-purine inhibitor of xanthine oxidase, reducing the conversion of hypoxanthine and xanthine to uric acid and thereby lowering serum urate.

Prescribing in practice

Febuxostat is associated with an increased risk of cardiovascular events and should be avoided in patients with major pre-existing cardiovascular disease (MHRA advice); review cardiovascular status before and during treatment.
Serious hypersensitivity reactions, including rare cutaneous reactions such as Stevens-Johnson syndrome, can occur—stop the drug if a rash develops.
Gout flares are common when starting; provide flare prophylaxis (e.g. colchicine or an NSAID) and do not stop febuxostat during an acute attack.

Monitoring

Monitor serum urate to confirm target lowering, liver function periodically, and remain alert for cardiovascular symptoms and hypersensitivity reactions.

Counselling the patient

Keep taking it during a gout attack—it is a preventive treatment, not a painkiller.
Expect possible flares early in treatment; take the prophylactic medicine as advised.
Stop and seek advice immediately if you develop a skin rash, and report chest pain or breathlessness.

Evidence & guidelines

Febuxostat is established for chronic gout, with its urate-lowering efficacy and cardiovascular safety signal documented in randomised trials, MHRA advice and NICE gout guidance.

Reference: MHRA DSU 2019 (cardiovascular safety); FAST Trial (Lancet 2020); NICE NG219 (Gout 2022); SPC Adenuric; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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