Quercetin
Quercetin is a flavonoid studied for allergy, inflammation, and exercise-recovery outcomes. Bioavailability varies by formulation.
Overview
What is quercetin?
Quercetin is a natural pigment found in many fruits and vegetables.
Dosage
A typical dose of quercetin is 250–500 mg per day.
Effect graph
Effect heatmap
SupplementDEX Database
36 conditions for and rated at least stars. All purchase bands. No minimum star filter.
Database Snapshot
Most quercetin research is concentrated in a handful of conditions.
- Athletic performance accounts for 6 of 66 studies (9%).
- COVID-19 accounts for 5 of 66 studies (8%).
- High blood pressure accounts for 5 of 66 studies (8%).
- Sparse coverage remains for Anxiety, Cardiovascular disease, Hay fever.
Dietary Sources
Top dietary sources
Ranked by amount per 100 g
- Raw yellow peppers50.6 mg100 g
- Red onions20 mg100 g
- Blueberries3.1 mg100 g
Other sources include Apples, Berries, Black and green tea, Capers, Citrus fruits, Cocoa, Cruciferous vegetables, Herbs, Leafy green vegetables, Olive oil, Onions, and Tomatoes.
Safety
Quercetin is possibly safe when used orally at doses of up to 1 gram per day for up to 12 weeks.
Frequently Asked Questions
References
Sources59 references
SupplementDEX uses only high-quality sources to determine supplement effectiveness.
SupplementDEX Database · Athletic performance
6 references1.SupplementDEX Database: Athletic performance — The effect of quercetin and citrulline on cycling time trial performance2024
In cyclists, 28 days of quercetin plus citrulline supplementation did not significantly improve time-trial performance versus placebo.
2.SupplementDEX Database: Athletic performance — Effects of a Singular Dose of Mangiferin-Quercetin Supplementation on Basketball Performance: A Double-Blind Crossover Study of High-Level Male Players2024
In 38 basketball players, pre-exercise mangiferin-quercetin (84/140 mg) shortened circuit time and lowered perceived exertion during a simulation test versus placebo.
3.SupplementDEX Database: Athletic performance — Effects of short-term quercetin supplementation on soldier performance2012
In soldiers, quercetin 1000 mg/day for 8.5 days did not improve VO2peak, loaded march performance, or cycling time trial versus placebo.
4.SupplementDEX Database: Athletic performance — Effect of quercetin supplementation on repeated-sprint performance, xanthine oxidase activity, and inflammation2011
In 15 men, quercetin 1000 mg/day for 1 week did not improve repeated-sprint performance and increased fatigue decrement versus carbohydrate placebo.
5.SupplementDEX Database: Athletic performance — Thermotolerance and heat acclimation may share a common mechanism in humans2011
In 8 men, quercetin 2000 mg/day blocked heat-acclimation benefits on GI permeability and cytokines during exercise-heat stress versus placebo.
6.SupplementDEX Database: Athletic performance — No effect of nutritional adenosine receptor antagonists on exercise performance in the heat2008
In 10 men exercising in heat, caffeine 9 mg/kg but not quercetin 2000 mg improved endurance performance; neither matched in vitro adenosine receptor inhibition levels affected outcomes.
SupplementDEX Database · Fatigue
1 reference7.SupplementDEX Database: Fatigue — Effects of 6 weeks of quercetin supplementation on energy, fatigue, and sleep in ROTC cadets2011
In 58 ROTC cadets, quercetin 1 g/day for 6 weeks during military training did not affect energy, fatigue, or sleep quality versus placebo.
SupplementDEX Database · High blood pressure
5 references8.SupplementDEX Database: High blood pressure — The Effects of Quercetin Supplementation on Blood Pressure - Meta-Analysis2022
A meta-analysis of 10 RCTs (841 adults) found quercetin supplementation modestly lowered systolic blood pressure overall and diastolic blood pressure in prehypertensive adults.
9.SupplementDEX Database: High blood pressure — Effect of quercetin supplementation on plasma lipid profiles, blood pressure, and glucose levels: a systematic review and meta-analysis2020
A meta-analysis of 17 RCTs (896 participants) found quercetin significantly lowered systolic and diastolic blood pressure over about 8 weeks, but did not significantly change lipid profiles or glucose.
10.SupplementDEX Database: High blood pressure — Effects of Quercetin on Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials2016
A meta-analysis of 7 RCTs (587 patients) found quercetin at ≥500 mg/day significantly reduced systolic and diastolic blood pressure.
11.SupplementDEX Database: High blood pressure — No evidence for a thermic effect of the dietary flavonol quercetin: a pilot study in healthy normal-weight women2010
In 6 healthy women, a single 150 mg dose of quercetin did not increase resting energy expenditure or change blood pressure over 3 hours or 24 hours.
12.SupplementDEX Database: High blood pressure — Quercetin reduces blood pressure in hypertensive subjects2007
In 22 adults with stage 1 hypertension, 730 mg/day quercetin for 28 days reduced systolic, diastolic, and mean arterial blood pressure versus placebo; prehypertensive adults showed no benefit.
SupplementDEX Database · High cholesterol
3 references13.SupplementDEX Database: High cholesterol — Effects of quercetin supplementation on lipid profile: A systematic review and meta-analysis of randomized controlled trials2017
A meta-analysis of 5 RCTs (442 participants) found quercetin did not significantly change LDL, HDL, or triglycerides, though total cholesterol rose slightly.
14.SupplementDEX Database: High cholesterol — Quercetin in the treatment of dyslipidemia2012
In 200 adults with dyslipidemia over 2 months, quercetin lowered cholesterol, triglycerides, and LDL and raised HDL versus placebo.
15.SupplementDEX Database: High cholesterol — Acute, quercetin-induced reductions in blood pressure in hypertensive individuals are not secondary to lower plasma angiotensin-converting enzyme activity or endothelin-1: nitric oxide2012
In 12 men with stage 1 hypertension, a single 1095 mg quercetin dose lowered mean blood pressure 10 hours later without changing ACE activity, endothelin-1, or flow-mediated dilation.
SupplementDEX Database · Sarcoidosis
1 reference16.SupplementDEX Database: Sarcoidosis — Quercetin reduces markers of oxidative stress and inflammation in sarcoidosis2011
In 12 patients with sarcoidosis, a single 2000 mg quercetin dose improved antioxidant capacity and reduced oxidative stress and inflammation markers in blood.
SupplementDEX Database · Anxiety
2 references17.SupplementDEX Database: Anxiety — The Impact of Three-Month Quercetin Intake on Quality of Life and Anxiety in Patients With Type II Diabetes Mellitus: An Early Data Analysis From a Randomized Controlled Trial2024
In 38 type 2 diabetes patients at 12-week interim follow-up, quercetin 500 mg/day improved FEV1 (+6.8% vs −0.3% in control) alongside usual care versus standard treatment alone.
18.SupplementDEX Database: Anxiety — Benefits of Quercetin on Glycated Hemoglobin, Blood Pressure, PiKo-6 Readings, Night-Time Sleep, Anxiety, and Quality of Life in Patients with Type 2 Diabetes Mellitus: A Randomized Controlled Trial2024
In 88 type 2 diabetes patients, quercetin 500 mg/day for 12 weeks lowered HbA1c −4.0% versus +0.1% in control and improved anxiety and quality-of-life scores.
SupplementDEX Database · Asthma
1 reference19.SupplementDEX Database: Asthma — Supplementary prevention and management of asthma with quercetin phytosome: a pilot registry2019
In a pilot registry, quercetin phytosome plus standard asthma care for 30 days improved peak expiratory flow, symptom control, and oxidative stress versus standard care alone.
20.SupplementDEX Database: Autism spectrum disorder — An open-label pilot study of a formulation containing the anti-inflammatory flavonoid luteolin and its effects on behavior in children with autism spectrum disorders2013
In 50 children with ASD (ages 4–10), open-label luteolin/quercetin supplement for 26 weeks improved adaptive behavior and communication on Vineland scales.
21.SupplementDEX Database: Benign prostatic hyperplasia (BPH) — Effects of Difaprost® on voiding dysfunction, histology and inflammation markers in patients with benign prostatic hyperplasia who are candidates for surgical treatment2014
In 36 BPH patients, 3 months of Difaprost (Serenoa, quercetin, beta-sitosterol) before surgery reduced post-void residual volume and showed less prostatic edema versus no pretreatment.
SupplementDEX Database · Beta-thalassemia
1 reference22.SupplementDEX Database: Beta-thalassemia — The effect of quercetin on iron overload and inflammation in β-thalassemia major patients: A double-blind randomized clinical trial2019
In 84 beta-thalassemia major patients, quercetin 500 mg/day for 12 weeks lowered hs-CRP, iron, ferritin, and transferrin saturation and raised transferrin versus placebo.
SupplementDEX Database · Canker sores
1 reference23.SupplementDEX Database: Canker sores — Management of aphthous ulceration with topical quercetin: a randomized clinical trial2010
In 40 aphthous ulcer patients, topical quercetin healed 100% of ulcers within 7–10 days versus benzydamine mouthwash, with smaller mean ulcer size at 10 days (p<0.004).
SupplementDEX Database · Cardiovascular disease
2 references24.SupplementDEX Database: Cardiovascular disease — Supplementation with quercetin markedly increases plasma quercetin concentration without effect on selected risk factors for heart disease in healthy subjects1998
In healthy adults with cholesterol 4.0–7.2 mmol/L, quercetin 1 g/day for 28 days raised plasma quercetin 23-fold but did not change lipids, blood pressure, or platelet function.
25.SupplementDEX Database: Cardiovascular disease — Dietary antioxidant flavonoids and risk of coronary heart disease: the Zutphen Elderly Study1993
In 805 Zutphen elderly men followed 5 years, highest flavonoid intake tertile (mainly from tea) had 58% lower coronary heart disease mortality (RR 0.42) than the lowest tertile, independent of major risk factors.
26.SupplementDEX Database: Chemotherapy-induced cystitis — Oral Preparation of Hyaluronic Acid, Chondroitin Sulfate, Curcumin, and Quercetin (Ialuril® Soft Gels) for the Prevention of LUTS after Intravesical Chemotherapy2022
In 34 non-muscle-invasive bladder cancer patients on intravesical mitomycin, oral hyaluronic acid/chondroitin/curcumin/quercetin (Ialuril) lowered IPSS LUTS scores at 4–13 months versus placebo.
27.SupplementDEX Database: Chronic obstructive pulmonary disease (COPD) — Effect of oral treatment with quercetin on inflammatory and oxidative stress markers in patients with chronic obstructive pulmonary disease2025
In 14 COPD patients with elevated CRP, quercetin 2000 mg/day for 6 months lowered BAL IL-8, IL-1β, and 8-isoprostane and serum SP-D versus placebo without adverse FEV1 changes.
28.SupplementDEX Database: Contrast induced nephropathy — Quercetin, a Promising Clinical Candidate for The Prevention of Contrast-Induced Nephropathy2019
In prediabetic/cath lab patients, quercetin pretreatment for 3–5 days reduced contrast-induced nephropathy incidence and protected glomerular filtration versus contrast media alone.
SupplementDEX Database · COVID-19
5 references29.SupplementDEX Database: COVID-19 — Quercetin for the treatment of COVID-19 patients: A systematic review and meta-analysis2023
A meta-analysis of 6 COVID-19 RCTs found quercetin reduced ICU admission (OR 0.31) and hospitalization (OR 0.25) but not mortality or no-recovery rate.
30.SupplementDEX Database: COVID-19 — Quercetin as a possible complementary agent for early-stage COVID-19: Concluding results of a randomized clinical trial2023
In 100 outpatients with early COVID-19, quercetin phytosome for 2 weeks accelerated viral clearance (34 vs 12 negative by week 1) and symptom resolution versus standard care.
31.SupplementDEX Database: COVID-19 — The therapeutic efficacy of quercetin in combination with antiviral drugs in hospitalized COVID-19 patients: A randomized controlled trial2022
In 60 hospitalized severe COVID-19 patients, quercetin 1000 mg/day plus antivirals for 7 days lowered ALP, q-CRP, and LDH versus antivirals alone.
32.SupplementDEX Database: COVID-19 — Possible Therapeutic Effects of Adjuvant Quercetin Supplementation Against Early-Stage COVID-19 Infection: A Prospective, Randomized, Controlled, and Open-Label Study2021
In 152 early COVID-19 outpatients, quercetin phytosome 1000 mg/day for 30 days reduced hospitalization, oxygen need, ICU admission, and deaths versus standard care alone.
33.SupplementDEX Database: COVID-19 — Potential Clinical Benefits of Quercetin in the Early Stage of COVID-19: Results of a Second, Pilot, Randomized, Controlled and Open-Label Clinical Trial2021
In 42 early COVID-19 outpatients, quercetin phytosome add-on cleared SARS-CoV-2 faster (16/21 negative by week 1 vs 2/21 control) and lowered LDH, ferritin, CRP, and D-dimer.
SupplementDEX Database · Depression
1 reference34.SupplementDEX Database: Depression — Effects of quercetin supplementation on endothelial dysfunction biomarkers and depression in post-myocardial infarction patients: A double-blind, placebo-controlled, randomized clinical trial2023
In 88 post-MI patients, quercetin 500 mg/day for 8 weeks did not significantly change ICAM-1, VCAM-1, or depression scores versus placebo.
35.SupplementDEX Database: Gastroesophageal reflux disease — Effects of Benesco™ on Esophageal Sensitivity, Mucosal Barrier Function, and Reflux Symptoms: A Mechanistic Study2025
In 8 GERD patients, Benesco (quercetin) for several weeks did not significantly change esophageal acid sensitivity, mucosal impedance, or reflux symptom scores.
SupplementDEX Database · Hay fever
2 references36.SupplementDEX Database: Hay fever — Effects of repeated oral intake of a quercetin-containing supplement on allergic reaction: a randomized, placebo-controlled, double-blind parallel-group study2022
In 66 Japanese adults with pollinosis, quercetin phytosome 200 mg/day for 4 weeks improved JRQLQ eye itching, sneezing, nasal discharge, and sleep scores versus placebo.
37.SupplementDEX Database: Hay fever — A polycentric, randomized, parallel-group, study on Lertal®, a multicomponent nutraceutical, as preventive treatment in children with allergic rhinoconjunctivitis: phase II2019
In 128 children with allergic rhinitis, continuing Lertal (Perilla, quercetin, vitamin D3) after antihistamines halved exacerbation risk (HR 0.54) and reduced rescue medication days versus observation.
SupplementDEX Database · Immunity
1 reference38.SupplementDEX Database: Immunity — Quercetin reduces illness but not immune perturbations after intensive exercise2007
In 40 trained cyclists over 3 weeks plus intensive exercise, 1000 mg/day quercetin did not alter exercise-induced immune changes but reduced upper respiratory tract infections (1/20 vs 9/20).
SupplementDEX Database · Kidney transplant
1 reference39.SupplementDEX Database: Kidney transplant — Beneficial effects of the bioflavonoids curcumin and quercetin on early function in cadaveric renal transplantation: a randomized placebo controlled trial2005
In 14 kidney transplant recipients, curcumin plus quercetin (480 mg/20 mg daily for 1 month) improved early graft function and lowered creatinine versus placebo.
SupplementDEX Database · Lung cancer
1 reference40.SupplementDEX Database: Lung cancer — Dietary flavonoid intake and smoking-related cancer risk: a meta-analysis2013
A meta-analysis of 35 observational studies (988,082 subjects) found higher dietary flavonoid intake associated with lower smoking-related cancer risk, especially aerodigestive tract cancers.
SupplementDEX Database · Metabolic syndrome
1 reference41.SupplementDEX Database: Metabolic syndrome — Effects of quercetin supplementation on glycemic control among patients with metabolic syndrome and related disorders: A systematic review and meta-analysis of randomized controlled trials2019
A meta-analysis in metabolic syndrome found quercetin did not overall lower fasting glucose or HbA1c, but ≥500 mg/day for ≥8 weeks reduced fasting glucose in subgroup analysis.
SupplementDEX Database · Muscle recovery
4 references42.SupplementDEX Database: Muscle recovery — Quercetin Supplementation Improves Neuromuscular Function Recovery from Muscle Damage2020
In 16 men, 1000 mg/day quercetin for 14 days after eccentric exercise improved neuromuscular recovery and reduced muscle damage markers versus placebo.
43.SupplementDEX Database: Muscle recovery — The Effects of Quercetin Supplementation on Eccentric Exercise-Induced Muscle Damage2019
In 12 men, 1000 mg/day quercetin for 14 days attenuated strength loss and neuromuscular impairment after eccentric exercise-induced muscle damage.
44.SupplementDEX Database: Muscle recovery — Quercetin's influence on exercise-induced changes in plasma cytokines and muscle and leukocyte cytokine mRNA2007
In 40 cyclists over 24 days, 1 g/day quercetin did not change post-exercise plasma cytokines but reduced leukocyte IL-8 and IL-10 mRNA.
45.SupplementDEX Database: Muscle recovery — Quercetin ingestion does not alter cytokine changes in athletes competing in the Western States Endurance Run2007
In 21 ultramarathon runners, 1000 mg/day quercetin for 3 weeks did not alter cytokine, cortisol, or CRP responses to a 160-km race versus placebo.
46.SupplementDEX Database: Nonalcoholic fatty liver disease — Efficacy of dietary polyphenol supplement in patients with non-alcoholic fatty liver disease: a network meta-analysis2025
A network meta-analysis of 54 RCTs (3132 NAFLD patients) found quercetin decreased serum TNF-α, while catechin and naringenin showed stronger effects on other metabolic markers.
SupplementDEX Database · Obesity
1 reference47.SupplementDEX Database: Obesity — Quercetin with vitamin C and niacin does not affect body mass or composition2011
In 941 adults over 12 weeks, 500 or 1000 mg/day quercetin with vitamin C and niacin did not change body mass, body composition, or lipids versus placebo.
SupplementDEX Database · Oral mucositis
1 reference48.SupplementDEX Database: Oral mucositis — A Randomized Placebo- Controlled Double Blind Clinical Trial of Quercetin in the Prevention and Treatment of Chemotherapy-Induced Oral Mucositis2017
In 20 adults with blood malignancies, 250 mg quercetin twice daily did not significantly reduce chemotherapy-induced oral mucositis incidence versus placebo.
SupplementDEX Database · Ovarian cancer
1 reference49.SupplementDEX Database: Ovarian cancer — A prospective study of dietary flavonoid intake and incidence of epithelial ovarian cancer2007
In 66,940 women followed up to 18 years, higher kaempferol and luteolin intake was associated with 40% and 34% lower ovarian cancer risk, respectively; total flavonoids showed no clear association.
SupplementDEX Database · Pancreatic cancer
2 references50.SupplementDEX Database: Pancreatic cancer — Flavonoid intake and risk of pancreatic cancer in male smokers (Finland)2008
In male smokers, higher flavonoid intake was linked to lower pancreatic cancer risk among placebo recipients but not among those taking alpha-tocopherol and beta-carotene.
51.SupplementDEX Database: Pancreatic cancer — Flavonols and pancreatic cancer risk: the multiethnic cohort study2007
In 183,518 adults over 8 years, higher flavonol intake was associated with 23% lower pancreatic cancer risk overall and stronger reductions in current smokers.
52.SupplementDEX Database: Physical performance — Effects of Quercetin Glycoside Supplementation Combined With Low-Intensity Resistance Training on Muscle Quantity and Stiffness: A Randomized, Controlled Trial2022
In 48 adults aged 50–74, 200 or 500 mg/day quercetin glycoside with low-intensity resistance training for 24 weeks reduced muscle stiffness but did not increase thigh muscle cross-sectional area.
53.SupplementDEX Database: Polycystic ovary syndrome (PCOS) — Quercetin and polycystic ovary syndrome; inflammation, hormonal parameters and pregnancy outcome: A randomized clinical trial2022
In 72 women with PCOS, 500 mg/day quercetin for 40 days lowered LH, TNF-α, and IL-6 and improved oocyte and embryo grade and pregnancy rate versus placebo.
54.SupplementDEX Database: Polycystic ovary syndrome (PCOS) — The effects of quercetin supplementation on metabolic and hormonal parameters as well as plasma concentration and gene expression of resistin in overweight or obese women with polycystic ovary syndrome2018
In 78 overweight women with PCOS, 1000 mg/day quercetin for 12 weeks lowered resistin, testosterone, and LH versus placebo, with modest metabolic improvements within the quercetin group.
55.SupplementDEX Database: Polycystic ovary syndrome (PCOS) — Effects of Quercetin on Adiponectin-Mediated Insulin Sensitivity in Polycystic Ovary Syndrome: A Randomized Placebo-Controlled Double-Blind Clinical Trial2017
In women with PCOS, 1 g/day quercetin for 12 weeks slightly raised adiponectin, lowered testosterone and LH, and reduced HOMA-IR versus placebo.
SupplementDEX Database · Prostatitis
1 reference56.SupplementDEX Database: Prostatitis — Quercetin in men with category III chronic prostatitis: a preliminary prospective, double-blind, placebo-controlled trial1999
In 17 men with chronic prostatitis, 500 mg quercetin twice daily for 1 month significantly improved NIH symptom scores versus placebo.
57.SupplementDEX Database: Rheumatoid arthritis — The Effect of Quercetin on Inflammatory Factors and Clinical Symptoms in Women with Rheumatoid Arthritis: A Double-Blind, Randomized Controlled Trial2017
In 50 women with rheumatoid arthritis, 500 mg/day quercetin for 8 weeks improved pain, disease activity, hs-TNF-α, and functional scores versus placebo.
SupplementDEX Database · Type 2 diabetes
1 reference58.SupplementDEX Database: Type 2 diabetes — Effect of emulin on blood glucose in type 2 diabetics2013
In 40 type 2 diabetics over 1 week, Emulin (quercetin-containing blend) with metformin lowered postprandial glucose and AUC more than either alone.
59.SupplementDEX Database: Upper respiratory tract infection (URTI) — Quercetin supplementation and upper respiratory tract infection: A randomized community clinical trial2010
In 1002 adults over 12 weeks, 500 or 1000 mg/day quercetin did not reduce upper respiratory infection rates overall; the 1000 mg group had fewer sick days in fit adults over 40.