Quercetin is a plant pigment from the flavonol family of flavonoids. It is the main flavonol in the human diet, mostly from tea, onions and apples. As a supplement it is sold for blood pressure, exercise recovery and “immune support,” and it is the “Q” in dasatinib plus quercetin (D + Q), the best-known senolytic combination studied in people.

The most important fact about quercetin is the size of its effects. Meta-analyses of randomized trials find blood pressure drops of about 2–3 mm Hg and endurance gains of 1–2%, which their own authors describe as small or trivial. The senolytic research comes from small pilot trials in which quercetin was always given together with dasatinib, a prescription cancer drug with serious side effects.

This page summarizes what clinical trials, meta-analyses and regulators report. It is for education only and is not medical advice.

Property	Detail
Class	Flavonol (a flavonoid polyphenol) found in plants
Formula	C₁₅H₁₀O₇, 302.23 g/mol (PubChem)
Main forms	Aglycone (sugar-free form, most supplements); glycosides such as quercetin glucosides (onions) and rutin (tea, buckwheat); lecithin “phytosome” formulations
Usual dietary intake	Mean ≈16 mg/day in Dutch adults (1987–1988 survey)
Doses in trials	Mostly 500–1,000 mg/day by mouth
Half-life	≈11 h for circulating quercetin metabolites after oral glycosides; 43 min for unchanged quercetin given IV
Interaction signals	Raised fexofenadine (P-gp) and pravastatin (OATP1B1) levels; altered CYP3A and CYP2C9 substrates in healthy volunteers
US status	Sold as a dietary supplement; FDA had “no questions” about a 2010 GRAS notice for food use up to 500 mg per serving
WADA status	Not named on the 2026 Prohibited List

What it is

Chemically, quercetin is 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxychromen-4-one (PubChem). In plants it occurs mainly bound to sugars, as glycosides such as rutin (Erlund et al., Eur J Clin Pharmacol 2000). The free molecule without the sugar is called the aglycone. Isolated quercetin in supplements is mostly the aglycone, often at daily doses of up to 1,000 mg, far above dietary intake (Andres et al., Mol Nutr Food Res 2018).

Dietary sources

A Dutch survey of 4,112 adults measured flavonoid intake with modern chromatography (Hertog et al., Nutr Cancer 1993):

Quercetin was the main flavonoid, with a mean intake of 16 mg/day.
The top sources of flavonoids overall were tea (48%), onions (29%) and apples (7%).

The form differs by food. Onions are rich in quercetin glucosides, while the main quercetin compound in tea is rutin (quercetin rutinoside) (Hollman et al., Am J Clin Nutr 1995).

Form	Where it occurs	What it means for absorption
Quercetin glucosides	Onions	Best absorbed of the natural forms
Rutin (quercetin rutinoside)	Tea, buckwheat	Slow absorption, with large differences between people
Aglycone	Most supplements	Poorly soluble; absorption between the two above
Lecithin phytosome	Branded supplements	Much higher blood levels than plain aglycone in short PK studies

Senolytic mechanism (cell and animal data)

Senolytics are compounds meant to kill senescent cells, old or damaged cells that stop dividing but release inflammatory signals called the senescence-associated secretory phenotype (SASP). The D + Q combination was chosen because, in culture and in animals, it removes senescent cells by temporarily disabling the survival pathways that protect them (Hickson et al., EBioMedicine 2019). Treatment is given intermittently (“hit-and-run”) rather than daily. In mice, the senescent-cell burden took weeks to return after a dose, which is the rationale for monthly or every-other-week schedules in human trials (Farr et al., Nat Med 2024).

The related flavonol fisetin is also promoted as a senolytic, and FOXO4-DRI is an experimental senolytic peptide.

Pharmacokinetics

How much quercetin is absorbed depends strongly on its form. After absorption it is extensively metabolized, and after oral glycosides it circulates mainly as glucuronide conjugates rather than the free molecule (Graefe et al., J Clin Pharmacol 2001).

Aglycone vs glycosides

Nine healthy people with an ileostomy (no colon, so unabsorbed quercetin could be collected) took three forms in random order (Hollman et al., Am J Clin Nutr 1995):

Form	Dose (as aglycone)	Share absorbed
Glucosides from fried onions	89 mg	52%
Pure aglycone	100 mg	24%
Pure rutin	100 mg	17%

A crossover study in 12 healthy volunteers found the sugar attached to quercetin mattered most (Graefe et al., J Clin Pharmacol 2001):

Product	Dose (as quercetin)	Peak plasma level	Time to peak
Onion supplement	100 mg	2.3 µg/mL	0.7 h
Quercetin-4′-O-glucoside	100 mg	2.1 µg/mL	0.7 h
Buckwheat tea	200 mg	0.6 µg/mL	4.3 h
Rutin	200 mg	0.3 µg/mL	7.0 h

Only quercetin glucuronides, not free quercetin, were found in plasma. The terminal elimination half-life was about 11 hours for all four products.

Enhanced formulations

A 2025 systematic review of 31 human studies compared ways of raising quercetin bioavailability (Liu et al., Food Chem 2025):

Approach	Reported bioavailability vs plain aglycone
Quercetin-3-O-oligoglucosides	≈20-fold
Lecithin phytosome	20.1-fold
Fenugreek galactomannan plus lecithin encapsulation	62-fold
Quercetin-3-O-glucoside in a γ-cyclodextrin complex	10.8-fold
Adding dietary fat and fiber	≈2-fold

The phytosome figure comes mainly from one single-dose crossover study in 12 volunteers run by the manufacturer’s employees (Riva et al., Eur J Drug Metab Pharmacokinet 2019). It compared 500 mg of plain quercetin with 500 mg of the phytosome product, which is about 40% quercetin by weight. Peak quercetin was 223 ng/mL with the phytosome, about 20 times higher, and total exposure (AUC) was about 18 times larger. Higher blood levels have not been shown to translate into larger clinical effects.

Intravenous quercetin

In a phase I cancer trial, quercetin given by short IV infusion was cleared quickly, with a median elimination half-life of 43 minutes (Ferry et al., Clin Cancer Res 1996). This describes unconjugated quercetin given IV, not oral supplements.

Regulatory status

United States. Quercetin is sold as a dietary supplement. In 2010 FDA closed GRAS notice 341 (from Quercegen Pharma) with “no questions.” It covered high-purity quercetin as an ingredient in beverages, grain products, processed fruits and juices, and soft candies at up to 500 mg per serving (FDA GRN 341). Quercetin is not an approved drug for any condition.
Sport. Quercetin is not named on the WADA 2026 Prohibited List.

What the research shows

Blood pressure

Two meta-analyses of randomized controlled trials found small reductions:

Meta-analysis	Trials (participants)	Systolic BP	Diastolic BP
Serban et al., J Am Heart Assoc 2016, all doses	7 (587)	−3.04 mm Hg (95% CI −5.75 to −0.33)	−2.63 mm Hg (95% CI −3.26 to −2.01)
Serban 2016, ≥500 mg/day	Subgroup	−4.45 mm Hg (95% CI −7.70 to −1.21)	−2.98 mm Hg (95% CI −3.64 to −2.31)
Serban 2016, under 500 mg/day	Subgroup	−1.59 mm Hg (not significant)	−0.24 mm Hg (not significant)
Popiolek-Kalisz & Fornal, Curr Probl Cardiol 2022, mixed population	10 (841)	−2.38 mm Hg (95% CI −3.80 to −0.96)	Significant only in (pre)hypertensive subgroup: −3.14 mm Hg (95% CI −4.44 to −1.84)

Serban’s dose split suggests the effect may be limited to 500 mg/day or more. However, the formal test comparing the two dose groups was not significant. The authors called for further studies of clinical relevance and of quercetin as an add-on to blood pressure drugs.

Endurance performance

Two meta-analyses found effects that were statistically significant but very small:

Meta-analysis	Studies (participants)	Typical dose and duration	Result
Kressler et al., Med Sci Sports Exerc 2011	11 (254)	Median 1,000 mg/day for 11 days	Effect size 0.15 (95% CI 0.02–0.27), ≈2% improvement; “between trivial and small”
Pelletier et al., Int J Sport Nutr Exerc Metab 2013	7 articles (288)	≈1,000 mg/day	Endurance performance +0.74% (95% CI 0.10–1.39); VO₂max +1.94% (95% CI 0.30–3.59)

In the Pelletier analysis, performance improved only in untrained people (+0.83%), not in trained people (+0.09%, p = 0.92). The authors concluded that quercetin is “unlikely to prove ergogenic” for aerobic exercise.

Muscle damage and soreness

A 2023 meta-analysis pooled 13 studies with 249 participants, almost all using 1,000 mg/day (Rojano-Ortega et al., Biol Sport 2023). Compared with placebo, quercetin was linked to:

less muscle soreness right after exercise (standardized mean difference −1.33);
lower creatine kinase, a muscle damage marker, at 24–48 h (SMD −1.15);
less post-exercise oxidative stress (SMD −0.92);
no change in the inflammatory marker IL-6.

The authors judged every included study to have some concerns about risk of bias, and the studies were small.

Immune function and colds

The immune claims rest mainly on two trials from the same research group:

Trial	Design	Result
Nieman et al., Med Sci Sports Exerc 2007	40 trained male cyclists; 1,000 mg/day or placebo for 3 weeks before, during and 2 weeks after 3 days of 3-hour rides	Upper respiratory tract infections (URTI) in the 2 weeks after: 1 of 20 vs 9 of 20 (p = 0.004). No difference in any measured immune marker.
Heinz et al., Pharmacol Res 2010	1,002 community adults aged 18–85; 500 mg/day, 1,000 mg/day or placebo for 12 weeks	No effect on URTI rates or symptoms overall, or by sex, BMI or age

In the larger trial, a subgroup analysis of 325 adults aged 40 or older who rated themselves as physically fit found 36% lower URTI severity and 31% fewer sick days with 1,000 mg/day. This was a secondary analysis in the larger trial, which was negative overall, so it should be treated as a hypothesis rather than a result.

Senolytic use with dasatinib

All human senolytic data for quercetin come from trials where it was combined with dasatinib. None tested quercetin alone, so these results cannot be attributed to quercetin. Most were pilot studies with 5–14 participants. Two senior investigators on most of these trials have a financial interest, including patents on senolytic drugs held by the Mayo Clinic, as the papers disclose.

Trial	Population and design	Regimen	Main findings
Justice et al., EBioMedicine 2019	Idiopathic pulmonary fibrosis (IPF); n = 14; open-label, no control group	D 100 mg/day + Q 1,250 mg/day, 3 days a week for 3 weeks	Feasible; 6-minute walk distance, gait speed and chair-stand time improved; lung function unchanged
Nambiar et al., EBioMedicine 2023	IPF; n = 12; randomized, placebo-controlled, single-blind	Same as above	No serious adverse events linked to D + Q; non-serious adverse events 65 vs 22 with placebo; function measures did not differ meaningfully (underpowered)
Hickson et al., EBioMedicine 2019	Diabetic kidney disease; n = 9; open-label	D 100 mg + Q 1,000 mg for 3 days	Fewer senescent-cell markers in fat and skin biopsies and lower circulating SASP factors 11 days later
Gonzales et al., Nat Med 2023	Mild Alzheimer’s disease; n = 5; open-label phase 1	D 100 mg + Q 1,000 mg on 2 consecutive days every 2 weeks, for 12 weeks	Dasatinib reached cerebrospinal fluid in 4 of 5; quercetin was not detected there; no change in cognition or brain imaging
Farr et al., Nat Med 2024	Postmenopausal women; n = 60; open-label phase 2 RCT vs no treatment	D 100 mg/day for 2 days + Q 1,000 mg/day for 3 days, every 28 days for 20 weeks	Primary endpoint (bone resorption marker CTx) not different: −4.1% vs −7.7% (p = 0.611); bone formation marker P1NP up 16% at 2 and 4 weeks but not at 20 weeks
Koning et al., Nat Metab 2026	Fibrotic metabolic dysfunction-associated steatohepatitis (MASH); n = 31; double-blind phase 2 RCT vs placebo	D 100 mg/day + Q 1,000 mg/day, 3 days a week for 3 weeks, over three 7-week cycles	Fibrosis improved by at least one stage without worsening of MASH in 47% vs 7% (p = 0.02); adverse events 82% vs 43%, all self-limiting

Taken together, these are early human pilot data. The only placebo-controlled trials so far had 12 and 31 participants. The 60-woman bone trial missed its primary endpoint. The quercetin product also differed between trials (Farr’s trial used a lecithin phytosome product), so quercetin doses are not directly comparable.

Dasatinib is not a supplement. Dasatinib (Sprycel) is a prescription kinase inhibitor approved for Philadelphia chromosome-positive chronic myeloid leukemia and acute lymphoblastic leukemia. Its label warns of severe drops in blood counts and bleeding, fluid retention including pleural effusions, cardiovascular toxicity, pulmonary arterial hypertension, QT prolongation and harm to a fetus (Sprycel label, DailyMed). In the trials above it was given under medical supervision with safety monitoring. Nothing on this page is guidance on using it.

Side effects and risks

Oral supplements

A review by scientists from Germany’s Federal Institute for Risk Assessment (BfR) found that adverse effects in human supplement studies were rarely reported and were mild (Andres et al., Mol Nutr Food Res 2018). The review also noted:

No adequate data exist on long-term use (over 12 weeks) of high doses (≥1,000 mg/day).
In animal studies, quercetin could worsen kidney damage in an already damaged kidney and could promote tumor growth, particularly in estrogen-dependent cancers. These are animal findings and have not been shown in people.
Quercetin can change the levels of some drugs (see below), so people on certain medicines may be a risk group.

Kidney effects at high IV doses

The kidney signal in humans comes from IV quercetin in cancer patients, not from oral supplements. In the phase I trial (Ferry et al., Clin Cancer Res 1996):

IV dose	Kidney toxicity
1,700 mg/m²	Dose-limiting kidney toxicity
1,400 mg/m²	2 of 10 patients (one grade 2, one grade 4)
945 mg/m²	3 of 14 patients (two grade 2, one grade 3)

Patients on the weekly schedule did not have cumulative kidney damage, but their glomerular filtration rate (a measure of kidney filtering) fell by 19% ± 8% in the 24 hours after each infusion.

Drug interactions

Small studies in healthy volunteers show that repeated quercetin doses can change how the body handles some drugs. They act on CYP enzymes (liver and gut enzymes that break down drugs), P-glycoprotein (P-gp, a pump that pushes drugs out of gut cells) and OATP1B1 (a liver uptake transporter):

Drug (pathway)	Quercetin regimen, n	Effect on the drug
Fexofenadine (P-gp)	500 mg three times daily for 7 days, n = 12	AUC +55%, peak +68%, oral clearance −37% (Kim et al., Eur J Clin Pharmacol 2009)
Pravastatin (OATP1B1)	500 mg/day for 14 days, n = 16	AUC +24%, peak +31% (Wu et al., Br J Clin Pharmacol 2012)
Midazolam (CYP3A)	500 mg/day for 13 days, n = 18	Lower exposure (AUC 165 vs 212 ng·h/mL) and shorter half-life (2.06 vs 2.75 h) in carriers of the CYP3A5*1 gene variant, consistent with CYP3A induction (Duan et al., J Clin Pharmacol 2012)
Diclofenac (CYP2C9)	500 mg twice daily for 10 days, n = 12	Higher peak, AUC and half-life of diclofenac; lower levels of its CYP2C9 metabolite (Bedada & Neerati, Phytother Res 2018)

These are short studies in healthy people and the directions differ by pathway. They show that quercetin at supplement doses is not pharmacologically inert. The dasatinib label separately warns against combining dasatinib with strong CYP3A4 inhibitors or inducers (Sprycel label).

Possible risk groups

The BfR review’s concerns point to people with existing kidney damage, people with estrogen-dependent cancers and people taking drugs whose levels quercetin can change. These concerns rest mainly on animal studies and short interaction studies, not on observed harm in supplement users (Andres et al., Mol Nutr Food Res 2018). Data on long-term use of 1,000 mg/day or more are lacking.

Key takeaways

A common dietary flavonol. Typical diets supply about 16 mg/day, mainly from tea, onions and apples; supplements usually provide 500–1,000 mg/day.
Form drives absorption. Onion glucosides were absorbed about twice as well as the aglycone, and lecithin phytosome products produced about 20-fold higher blood levels in a small manufacturer-run study.
Small blood pressure effect. Meta-analyses found drops of about 2–3 mm Hg systolic, possibly only at 500 mg/day or more.
Little for performance. Endurance gains were about 1–2% and judged trivial to small; recovery data are small and at some risk of bias. A large community trial found no effect on colds overall.
Senolytic data are early and always paired with dasatinib. Pilot trials of D + Q are small, mostly uncontrolled, and dasatinib is a prescription leukemia drug with serious label warnings.
Not inert. Repeated doses altered levels of fexofenadine, pravastatin, midazolam and diclofenac, and high IV doses caused kidney toxicity in a cancer trial.

Sources

Hertog MG, Hollman PC, Katan MB, et al. Intake of potentially anticarcinogenic flavonoids and their determinants in adults in The Netherlands. Nutr Cancer. 1993;20(1):21–29. PubMed.
Hollman PC, de Vries JH, van Leeuwen SD, et al. Absorption of dietary quercetin glycosides and quercetin in healthy ileostomy volunteers. Am J Clin Nutr. 1995;62(6):1276–1282. PubMed.
Erlund I, Kosonen T, Alfthan G, et al. Pharmacokinetics of quercetin from quercetin aglycone and rutin in healthy volunteers. Eur J Clin Pharmacol. 2000;56(8):545–553. PubMed.
Graefe EU, Wittig J, Mueller S, et al. Pharmacokinetics and bioavailability of quercetin glycosides in humans. J Clin Pharmacol. 2001;41(5):492–499. PubMed.
Riva A, Ronchi M, Petrangolini G, et al. Improved oral absorption of quercetin from Quercetin Phytosome, a new delivery system based on food grade lecithin. Eur J Drug Metab Pharmacokinet. 2019;44(2):169–177. PubMed.
Liu L, Barber E, Kellow NJ, et al. Improving quercetin bioavailability: a systematic review and meta-analysis of human intervention studies. Food Chem. 2025;477:143630. PubMed.
Ferry DR, Smith A, Malkhandi J, et al. Phase I clinical trial of the flavonoid quercetin: pharmacokinetics and evidence for in vivo tyrosine kinase inhibition. Clin Cancer Res. 1996;2(4):659–668. PubMed.
Serban MC, Sahebkar A, Zanchetti A, et al. Effects of quercetin on blood pressure: a systematic review and meta-analysis of randomized controlled trials. J Am Heart Assoc. 2016;5(7):e002713. PubMed.
Popiolek-Kalisz J, Fornal E. The effects of quercetin supplementation on blood pressure - meta-analysis. Curr Probl Cardiol. 2022;47(11):101350. PubMed.
Kressler J, Millard-Stafford M, Warren GL. Quercetin and endurance exercise capacity: a systematic review and meta-analysis. Med Sci Sports Exerc. 2011;43(12):2396–2404. PubMed.
Pelletier DM, Lacerte G, Goulet ED. Effects of quercetin supplementation on endurance performance and maximal oxygen consumption: a meta-analysis. Int J Sport Nutr Exerc Metab. 2013;23(1):73–82. PubMed.
Rojano-Ortega D, Peña-Amaro J, Berral-Aguilar AJ, et al. Quercetin supplementation promotes recovery after exercise-induced muscle damage: a systematic review and meta-analysis of randomized controlled trials. Biol Sport. 2023;40(3):813–825. PubMed.
Nieman DC, Henson DA, Gross SJ, et al. Quercetin reduces illness but not immune perturbations after intensive exercise. Med Sci Sports Exerc. 2007;39(9):1561–1569. PubMed.
Heinz SA, Henson DA, Austin MD, et al. Quercetin supplementation and upper respiratory tract infection: a randomized community clinical trial. Pharmacol Res. 2010;62(3):237–242. PubMed.
Justice JN, Nambiar AM, Tchkonia T, et al. Senolytics in idiopathic pulmonary fibrosis: results from a first-in-human, open-label, pilot study. EBioMedicine. 2019;40:554–563. PubMed.
Nambiar A, Kellogg D 3rd, Justice J, et al. Senolytics dasatinib and quercetin in idiopathic pulmonary fibrosis: results of a phase I, single-blind, single-center, randomized, placebo-controlled pilot trial on feasibility and tolerability. EBioMedicine. 2023;90:104481. PubMed.
Hickson LJ, Langhi Prata LGP, Bobart SA, et al. Senolytics decrease senescent cells in humans: preliminary report from a clinical trial of dasatinib plus quercetin in individuals with diabetic kidney disease. EBioMedicine. 2019;47:446–456. PubMed.
Gonzales MM, Garbarino VR, Kautz TF, et al. Senolytic therapy in mild Alzheimer’s disease: a phase 1 feasibility trial. Nat Med. 2023;29(10):2481–2488. PubMed.
Farr JN, Atkinson EJ, Achenbach SJ, et al. Effects of intermittent senolytic therapy on bone metabolism in postmenopausal women: a phase 2 randomized controlled trial. Nat Med. 2024;30(9):2605–2612. PubMed.
Koning M, Kovynev A, Fondevila MF, et al. Senolytics dasatinib and quercetin in metabolic dysfunction-associated steatohepatitis: a proof-of-principle randomized, controlled trial. Nat Metab. 2026; published online October 1, 2026. DOI; PubMed.
Andres S, Pevny S, Ziegenhagen R, et al. Safety aspects of the use of quercetin as a dietary supplement. Mol Nutr Food Res. 2018;62(1):e1700447. PubMed.
Kim KA, Park PW, Park JY. Short-term effect of quercetin on the pharmacokinetics of fexofenadine, a substrate of P-glycoprotein, in healthy volunteers. Eur J Clin Pharmacol. 2009;65(6):609–614. PubMed.
Wu LX, Guo CX, Chen WQ, et al. Inhibition of the organic anion-transporting polypeptide 1B1 by quercetin: an in vitro and in vivo assessment. Br J Clin Pharmacol. 2012;73(5):750–757. PubMed.
Duan KM, Wang SY, Ouyang W, et al. Effect of quercetin on CYP3A activity in Chinese healthy participants. J Clin Pharmacol. 2012;52(6):940–946. PubMed.
Bedada SK, Neerati P. Evaluation of the effect of quercetin treatment on CYP2C9 enzyme activity of diclofenac in healthy human volunteers. Phytother Res. 2018;32(2):305–311. PubMed.
E.R. Squibb & Sons. Sprycel (dasatinib) tablets prescribing information. DailyMed.
Food and Drug Administration. GRAS Notice No. 341: Quercetin (Quercegen Pharma LLC). Closed November 22, 2010. FDA.
National Center for Biotechnology Information. Quercetin, PubChem CID 5280343. PubChem.
World Anti-Doping Agency. The 2026 Prohibited List. WADA 2026 Prohibited List.

Quercetin