Quercetin
FlavonoidAlso known as: Quercetin dihydrate · Quercetin phytosome
A plant flavonoid with anti-inflammatory, antioxidant, and senolytic properties. Studied for immune function, cardiovascular health, and as part of senolytic protocols (with dasatinib). Poor bioavailability requires enhanced formulations.
How expert claims hold up
79 of 92 claims assessed22 of 79 assessed claims supported or partially supported by published research
Expert Consensus
Dose divergence: Experts recommend different amounts (250-500milligrams, 500milligrams). Check the Stack & Timing tab for study-backed dosing ranges.
Evidence Summary
Quercetin is a naturally occurring flavonoid polyphenol found in common foods such as onions, capers, apples, and kale, and has been the subject of scientific investigation for several decades. The available literature — consisting primarily of reviews and systematic reviews, with a small number of meta-analyses — suggests quercetin has broad biological activity, including antioxidant, anti-inflammatory, anti-allergic, and potentially cardioprotective properties. However, the majority of expert claims about quercetin's specific health benefits were rated as having insufficient evidence, meaning the research base, while active, has not yet produced consistent, high-quality human trial data to firmly support many of the therapeutic applications being discussed. Across the 15 available publications, the strongest evidence comes from meta-analyses examining quercetin's effects on blood pressure and its bioavailability in humans, as well as systematic reviews on bone metabolism and cardiovascular risk reduction. These higher-quality studies suggest quercetin supplementation may modestly influence blood pressure and that its bioavailability varies considerably depending on the delivery format. Systematic reviews also touch on quercetin's potential roles in rheumatoid arthritis disease activity and bone health, though findings across these areas are not consistently robust. Reviews covering inflammation, allergy, exercise-induced muscle damage, Alzheimer's prevention, diabetes management, and anti-aging applications exist but are largely narrative in nature and do not provide the same level of evidential weight. A major limitation across this evidence base is that the majority of publications are reviews rather than original clinical trials — and even the systematic reviews frequently draw on studies with small sample sizes, heterogeneous populations, and variable dosing protocols. Crucially, none of the listed studies report specific participant populations or sample sizes, which makes it difficult to assess how broadly any findings apply. More than 70% of the expert claims analyzed were classified as having insufficient evidence, underscoring that quercetin remains a supplement with considerable theoretical and preclinical support but limited definitive human trial data. Key unknowns include optimal dosing, long-term safety at supplemental doses, and whether benefits observed in controlled settings translate to real-world outcomes.
Read full evidence summary →Top studies
The Effects of Quercetin Supplementation on Blood Pressure - Meta-Analysis.
The Effects of Quercetin Supplementation on Blood Pressure - Meta-Analysis.
Improving quercetin bioavailability: A systematic review and meta-analysis of human intervention studies.
Improving quercetin bioavailability: A systematic review and meta-analysis of human intervention studies.
Expert Mentions
All 92 mentions
“For daily anti-inflammatory and antioxidant support, lower doses of 250 to 500 milligrams of a bioavailable formulation are more typical.”
For daily anti-inflammatory and antioxidant support, lower doses of 250 to 500 milligrams of a bioavailable formulation are more typical.
None of the 10 retrieved studies provide extractable key findings, populations, or limitations, making it impossible to directly evaluate the specific dose range of 250–500 mg of a bioavailable querce…
“For daily anti-inflammatory and antioxidant support, lower doses of 250 to 500 milligrams of a bioavailable formulation are more typical.”
For daily anti-inflammatory and antioxidant support, lower doses of 250 to 500 milligrams of a bioavailable formulation are more typical.
None of the 10 retrieved studies provide extractable key findings, population data, or dose-specific details that directly evaluate the 250–500 mg quercetin range for daily anti-inflammatory or antiox…
Safety, interactions & who should avoid Quercetin
generally_recognized_safe
A dedicated review on the safety of quercetin as a dietary supplement suggests it is generally well-tolerated at typical supplemental doses, with no major adverse effects reported in short-term use. However, long-term safety data in humans remains limited, and caution is warranted at high doses or when combined with certain medications.
Quercetin is generally considered safe at commonly studied doses (up to ~1000 mg/day) in short-to-medium term use; a dedicated safety review indicates a favorable profile at these levels, though very high doses or prolonged use have not been thoroughly characterized in humans. At high doses, mild gastrointestinal discomfort has been reported.
Who should avoid it
Individuals on anticoagulant therapy, immunosuppressants, or drugs with narrow therapeutic windows should consult a physician before use due to potential CYP enzyme interactions. Pregnant or breastfeeding individuals should exercise caution given insufficient safety data in these populations. Those with kidney disease should use caution, as high-dose quercetin metabolites may place additional renal burden.
Known interactions
- ·May interact with anticoagulant/antiplatelet drugs (e.g., warfarin) by affecting platelet aggregation and drug metabolism
- ·May inhibit CYP3A4 and CYP2C8 enzymes, potentially altering the metabolism of certain medications including some statins and chemotherapy agents
- ·May potentiate the effects of antihypertensive medications given modest blood-pressure-lowering effects identified in meta-analysis
- ·May interact with antibiotics, particularly fluoroquinolones, by chelating metal ions or altering gut microbiota
Pregnancy & breastfeeding
Our sources specifically flag pregnancy or breastfeeding considerations for Quercetin — see the cautions above.
We don’t assign pregnancy-safety ratings. Many supplements lack adequate safety data in pregnancy and breastfeeding, and the absence of a warning here does not mean a supplement is safe to take. Don’t start, stop, or continue any supplement while pregnant or nursing without your OB-GYN or midwife.
Read: Supplements during pregnancy & breastfeeding →This is educational information only. Consult a healthcare provider before starting any supplement.
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Key findings
- ·Quercetin is a well-characterized flavonoid polyphenol found in many common plant-based foods and has been studied for decades for its antioxidant and anti-inflammatory properties.
- ·A meta-analysis suggests quercetin supplementation may have a modest effect on reducing blood pressure, though the magnitude and clinical significance remain unclear.
- ·Bioavailability of quercetin varies substantially depending on the supplement form used, as highlighted by a systematic review and meta-analysis on human intervention studies.
Evidence gaps
- ·The vast majority of claims about quercetin's therapeutic benefits lack sufficient human clinical trial evidence — most support comes from in vitro, animal, or low-quality human studies.
- ·Optimal supplemental dosing, timing, and formulation for specific health outcomes have not been established in well-designed, large-scale human trials.
- ·Long-term effects and safety of quercetin supplementation at doses commonly used in supplements have not been thoroughly evaluated in human populations.