Gout and High Uric Acid: Treating a Flare, How Low Urate Should Go, Using Allopurinol Correctly, and Which Drugs to Avoid with Kidney Disease

What gout is

When blood uric acid is high (hyperuricaemia, usually >6.8–7.0 mg/dL — the solubility limit of urate at body temperature), monosodium urate crystals deposit in joints and soft tissue and trigger intense inflammation: gout [1][2]. About 56 million people are affected, men 3–4 times more than women; Taiwan has one of the highest adult hyperuricaemia rates in the world, above 20% [3].

Not everyone with high urate gets gout — only about a third do. But gout is more than joint pain: it is strongly linked to CKD, hypertension, cardiovascular disease and the metabolic syndrome [1][2].

The acute flare: typical picture and three drugs

A classic flare: sudden severe pain at night, most often at the base of the big toe (first MTP joint), sometimes ankle, knee or wrist; the joint is red, swollen and so hot and tender that a bedsheet hurts; untreated it settles in 7–14 days [1][2].

ACR 2020 advises treating as early as possible (ideally within 24 hours). Three classes are equally effective; choose by co-morbidity [1]:

IL-1 inhibitors (anakinra, canakinumab) are options when oral drugs cannot be used [1][2]. Do not stop urate-lowering therapy during a flare [1].

Urate-lowering therapy (ULT): who needs it and the target

Who [1][2]

Strongly recommended: ≥2 flares a year; tophi; radiographic joint damage. Conditionally recommended: first flare with CKD stage ≥3, urate >9 mg/dL, or kidney stones. Not recommended: asymptomatic hyperuricaemia (see below).

Treat-to-target

ACR and EULAR agree on lowering serum urate to <6.0 mg/dL (360 µmol/L) and keeping it there; with tophi, lower (<5.0) speeds dissolution [1][2]. This requires regular urate testing and dose titration, not a fixed dose for life.

First-line: allopurinol

Allopurinol is the ACR's strongly recommended first choice, including in CKD stage 3 and above [1]:

• Start low: generally ≤100 mg/day; from 50 mg/day in CKD ≥3, increasing every 2–5 weeks until target, and doses may exceed 300 mg/day (the old practice of capping dose by kidney function led to under-treatment) [1].
• Why start low: it reduces the risk of severe cutaneous adverse reactions (SCAR/DRESS/Stevens–Johnson); a high starting dose is a major risk factor.
• HLA-B*5801 screening: this allele is strongly associated with severe allopurinol hypersensitivity and is common in Han Chinese (≈15–20% carriers in Taiwan), Koreans and Thais; ACR conditionally recommends testing before starting in these groups (covered by Taiwan's national insurance); carriers use an alternative [1][4].
• Flares may increase in the first 3–6 months (rapid urate shifts), so ACR recommends prophylactic low-dose colchicine or NSAID/steroid for 3–6 months alongside [1].

Second-line: febuxostat

More potent than allopurinol and unaffected by kidney function (no adjustment at eGFR ≥30), but the CARES trial showed higher cardiovascular death than allopurinol, prompting an FDA boxed warning; the later European FAST trial found no difference [5][6]. ACR: prefer allopurinol in those with cardiovascular disease, reserving febuxostat for allopurinol intolerance or HLA-B*5801 positivity [1].

Uricosurics

Probenecid, benzbromarone (available in Taiwan, not the US): ineffective at eGFR <30 and unsuitable with urinary stones [1][2].

Diet and lifestyle: smaller effect than you think, but still useful

Diet shifts urate by only about 1 mg/dL and cannot replace medication, but it reduces flares [1][2]:

• Reduce: beer and spirits (wine matters less), sugary drinks and fructose, offal, red meat, some seafood (sardines, anchovies, shellfish).
• Fine to eat: low-fat dairy, vegetables (purine-rich vegetables such as spinach, asparagus and mushrooms do not raise gout risk), coffee, cherries (weak evidence).
• Weight loss matters more than any single food.
• Review medications: thiazide and loop diuretics, low-dose aspirin and ciclosporin/tacrolimus raise urate (gout prevalence after transplant is 10–28%); losartan and SGLT2 inhibitors lower urate and may be preferred when co-morbidities allow [1][2].

Kidney patients: three common questions

1. Should asymptomatic hyperuricaemia be treated? Lowering urate was once thought to protect kidneys, but two large 2020 RCTs (CKD-FIX, PERL) showed allopurinol did not slow CKD progression [7]. KDIGO 2024 therefore recommends against treating asymptomatic hyperuricaemia solely to slow CKD [8]. Treat gout, not the number.

2. Gout on dialysis Dialysis removes urate, so flares are actually less common; steroids are the mainstay if they occur; colchicine is strictly limited; allopurinol is given after dialysis.

3. Transplant recipients Ciclosporin raises urate most (tacrolimus somewhat less); azathioprine must never be combined with allopurinol or febuxostat (life-threatening marrow suppression) — mycophenolate does not have this problem. NSAIDs are contraindicated in flares; colchicine with ciclosporin/tacrolimus needs dose reduction and monitoring. Use this site's interaction lookup.

When to seek care

Urgently: a red, hot, swollen joint with fever or chills (septic arthritis must be excluded, possibly by joint aspiration); rash, fever, mouth ulcers or red eyes soon after starting allopurinol (possible severe hypersensitivity — stop and seek care immediately).

Routine appointment: ≥2 flares a year; firm lumps near joints (tophi); urate >9; kidney stones.

Questions to ask your doctor

1. Do I need long-term urate-lowering therapy? What is my target, and how often should urate be checked?
2. Should I have HLA-B*5801 testing before allopurinol?
3. With my kidney function, which flare medication should I keep at home?
4. Do my diuretics, aspirin or anti-rejection drugs raise urate? Are there alternatives?
5. (Transplant) Do my immunosuppressants interact with gout drugs?

References

1. FitzGerald JD, et al. 2020 ACR Guideline for the Management of Gout. Arthritis Care Res. 2020;72(6):744–760. https://doi.org/10.1002/acr.24180
2. Richette P, et al. 2016 updated EULAR recommendations for the management of gout. Ann Rheum Dis. 2017;76(1):29–42. https://doi.org/10.1136/annrheumdis-2016-209707
3. Dehlin M, Jacobsson L, Roddy E. Global epidemiology of gout. Nat Rev Rheumatol. 2020;16(7):380–390. https://doi.org/10.1038/s41584-020-0441-1
4. Hung SI, et al. HLA-B*5801 allele as a genetic marker for severe cutaneous adverse reactions caused by allopurinol. Proc Natl Acad Sci USA. 2005;102(11):4134–4139. https://doi.org/10.1073/pnas.0409500102
5. White WB, et al. CARES. N Engl J Med. 2018;378(13):1200–1210. https://doi.org/10.1056/NEJMoa1710895
6. Mackenzie IS, et al. FAST. Lancet. 2020;396(10264):1745–1757. https://doi.org/10.1016/S0140-6736(20)32234-0
7. Badve SV, et al. CKD-FIX. N Engl J Med. 2020;382(26):2504–2513. https://doi.org/10.1056/NEJMoa1915833
8. KDIGO 2024 Clinical Practice Guideline for CKD. Kidney Int. 2024;105(4S):S117–S314. https://doi.org/10.1016/j.kint.2023.10.018

This article compiles publicly available medical information for educational purposes only. It is not medical advice and has not been reviewed by a practising physician. For any health or medication question, consult a qualified professional. For chest pain, sudden breathlessness, one-sided weakness or slurred speech, call your local emergency number or go to the emergency department immediately.