Quercetin for Gout

Quercetin may lower uric acid a little, but no study has tested whether it prevents gout flares. The best evidence is one randomised, double-blind crossover trial in 22 healthy men with high-normal uric acid: 500 mg a day for 4 weeks lowered plasma uric acid by 26.5 µmol/L (about 0.45 mg/dL) compared with placebo (Shi 2016).

That is a real but modest signal. Real-life cohorts with a phytosome form at 400 mg a day reported 13-15% falls, but without placebo control (Di Pierro 2025); a trial of 50-150 mg a day found no change (Egert 2008); and no study has counted flares. For people with gout who need urate-lowering treatment, guidelines recommend allopurinol first, aiming for a serum urate below 6 mg/dL (Richette 2017; FitzGerald 2020).

Uric acid is made by xanthine oxidase, the same enzyme allopurinol blocks. Quercetin fits into the enzyme's active site in a crystal structure (Cao 2014), and its circulating metabolite quercetin-3'-sulfate inhibits it in the test tube (Tumova 2021). Some quercetin metabolites were even stronger inhibitors than the parent compound and than allopurinol in one enzyme assay (Mohos 2019).

The authors of the main trial propose that this enzyme block, by quercetin-3'-sulfate, is how quercetin lowers uric acid in people (Tumova 2021). In rodents with induced high uric acid, a meta-analysis of animal studies found quercetin lowered kidney damage markers and acted on several pathways, including urate transporters (Bian 2025).

Lab and animal results don't settle what happens in people. In 12 healthy volunteers, 13 days of 500 mg quercetin a day increased a caffeine-based marker of xanthine oxidase activity by 15.0%, the opposite of what the enzyme theory predicts (Chen 2009). In 15 young men, 1,000 mg a day of a quercetin glucoside for a week did not blunt the rise in xanthine oxidase or uric acid after sprinting (Abbey 2011).

Neither study measured resting uric acid in people with hyperuricaemia, so they don't cancel out the main trial. They do mean the mechanism is plausible rather than proven in humans. And in rats with gout-like joint pain, quercetin alone had minimal pain-relieving or anti-inflammatory effect (Aviles-Herrera 2025), so it is not a flare treatment.

The placebo-controlled trial used one 500 mg quercetin tablet a day for 4 weeks (Shi 2016). The real-life cohorts used 400 mg of quercetin a day as a phytosome (a form bound to phospholipids) for up to 90 days (Di Pierro 2025).

Lower doses may not be enough: 50, 100 or 150 mg a day for 2 weeks raised blood quercetin but left serum uric acid unchanged (Egert 2008). Supplements are often sold at up to 1,000 mg a day, but there are no adequate safety data for 1,000 mg or more taken for longer than 12 weeks (Andres 2018).

Shi and Williamson recruited 22 healthy men aged 19-60 whose plasma uric acid averaged 339 µmol/L, high but still in the healthy range. Each man took 500 mg quercetin daily for 4 weeks and a placebo for 4 weeks, in random order and double-blind, with a 4-week washout between (Shi 2016).

Quercetin lowered plasma uric acid by 26.5 µmol/L compared with placebo (95% CI 7.6 to 45.5; P=0.008), roughly an 8% fall from the average starting level. It did not change 24-hour urinary uric acid, fasting glucose or blood pressure (Shi 2016). Nobody in the trial had gout, and it included no women.

Three real-life cohorts in Italy gave 400 mg of quercetin a day as a phytosome. Uric acid fell by 15.2% in men and 13.8% in women in a cohort of healthy adults, compared with no significant change in a group given a probiotic, and by 13.1% and 13.7% in two smaller groups with raised uric acid (Di Pierro 2025). These groups were not randomised or placebo-controlled, and the authors call for larger randomised trials.

The only study in people with gout followed 84 men with gout and high blood pressure for 12 months, 43 of whom had quercetin added to their usual blood pressure and urate-lowering treatment (Kondratiuk 2018). The abstract reports better heart-function measures and a 33.7% fall in uric acid with the combination, but doesn't say whether allocation was random, what dose was used, or how the comparison group's uric acid changed.

A 2-week randomised trial of 50-150 mg quercetin a day in 35 healthy volunteers found no change in serum uric acid (Egert 2008). A 2026 meta-analysis of 21 randomised trials found that flavonoid supplements as a group lowered serum uric acid, but its abstract does not report a separate result for quercetin (Xie 2026).

What's missing matters more for gout: no randomised trial in people with gout, no trial that counts flares or tophi, no trial longer than 12 weeks with placebo, and no comparison with allopurinol. For other supplements studied for gout, see the evidence for tart cherry and vitamin C.

Adverse effects from quercetin supplements have rarely been reported in human studies, and those reported were mild, according to a 2018 review of quercetin supplement safety (Andres 2018). The phytosome cohorts reported minimal, transient side effects at 400 mg a day (Di Pierro 2025), and a 6-week trial at 150 mg a day found no adverse changes in liver, kidney or blood markers (Egert 2009).

The same review flags animal evidence that quercetin may increase damage in an already injured kidney, and notes there are no adequate safety data for 1,000 mg a day or more beyond 12 weeks (Andres 2018). That matters in gout, because high uric acid is linked to chronic kidney disease (Nutmakul 2022). The review also notes animal evidence that quercetin may promote tumour development, especially in oestrogen-dependent cancers (Andres 2018). None of the gout or uric acid studies included pregnant or breastfeeding women.

Quercetin changes how some drugs are handled. In healthy volunteers it lowered CYP1A2 activity by 10.4% and raised CYP2A6 and NAT2 activity (Chen 2009), and a 2018 safety review notes that single and short-term doses altered the bioavailability of certain drugs (Andres 2018).

Two points matter most in gout. First, xanthine oxidase also breaks down 6-mercaptopurine. The febuxostat label warns that combining a xanthine oxidase inhibitor drug with azathioprine or mercaptopurine could raise their levels and cause severe toxicity, and lists the combination as a contraindication (febuxostat prescribing information). Quercetin metabolites inhibit the same enzyme in lab tests, more strongly than allopurinol in one assay, and the researchers warned of possible interactions with these drugs (Mohos 2019). Avoid quercetin with them unless your prescriber agrees. Second, in rats with gout-like joint pain, quercetin reduced the pain relief from diclofenac, indomethacin and ketorolac (Ventura-Martinez 2021; Aviles-Herrera 2025). Neither interaction has been tested in people.