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Quercetin

Aliases (1)

QUERCETIN

TYPICAL DOSE

| Quercetin aglycone

ROUTE

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CYCLE

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STORAGE

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Overview

What is Quercetin?

Dietary flavonoid from onions, apples, capers, and tea — a competent mast cell stabilizer + modest antihypertensive that's massively under-delivered by the standard aglycone capsule (≈1–2% bioavailability). 500–1000 mg/day of plain quercetin is mostly a vitamin-C-tier hedge; Quercefit phytosome 250–500 mg/day or quercetin-3-O-glucoside from Sophora japonica is what makes the molecule actually hit plasma. Two interesting use cases: seasonal allergic rhinitis (Mlcek 2016 mechanistic + small RCTs — real but moderate effect) and research-grade senolytic when paired with dasatinib in the Mayo Clinic D+Q protocol (Justice 2019 IPF pilot, Hickson 2019 diabetic CKD — proof-of-concept only, requires Rx dasatinib). For Dylan: OPTIONAL-ADD during allergy season at phytosome dose; not core daily stack. Watch warfarin (don't), watch levothyroxine timing (separate ≥4 hr).

Pharmacokinetics

PeakHalf-life

Approximate curve — visual aid only, not data-precise PK

Research Indications

Most Effective

NF-κB inhibition

blocks IκB phosphorylation, suppressing transcription of TNF-α, IL-1β, IL-6, IL-8, COX-2, iNOS in macrophages and epithelial cells.

Effective

Nrf2 activation

induces phase-II antioxidant defenses (HO-1, NQO1, glutathione synthesis enzymes) via Keap1-Nrf2-ARE pathway.

Investigational

Direct ROS scavenging

the catechol B-ring and 3-OH/4-keto motif make quercetin a competent peroxyl-radical sink; also chelates Fe²⁺/Cu²⁺ which prevents Fenton-…

Peptide Interactions

Bromelain (250 mg with each 500 mg quercetin):

Synergistic

Classic "natural antihistamine" stack. Bromelain (pineapple enzyme) may modestly enhance quercetin absorption and adds independent anti-inflammatory effect (…

Vitamin C (500 mg):

Synergistic

Recycles oxidized quercetin back to active form; adds independent antihistamine effect via cofactor role in histamine degradation. The Linus Pauling vitamin-…

Resveratrol:

Synergistic

Adjacent polyphenol with overlapping anti-inflammatory and senescence-modifying mechanisms; both poorly bioavailable as aglycones. The combo is more marketin…

Fisetin:

Synergistic

Related senolytic flavonoid (apples, strawberries). Used at high doses (1.5 g/day, 2 consecutive days/month) in the planned Mayo Clinic senolytic protocols. …

Curcumin (already in Dylan's V4):

Synergistic

Independent NF-κB inhibitor + COX-2 inhibitor. Complementary anti-inflammatory profile. Both share poor aglycone bioavailability; both benefit from phytosome…

NAC (community signal: 119 co-mentions):

Synergistic

Cysteine donor / glutathione precursor — pairs with quercetin's Nrf2 induction. Also relevant for the antiviral / COVID-era stack rationale.

Omega-3 (community signal: 138 co-mentions):

Synergistic

Resolvin-pathway synergy on inflammation resolution; no direct interaction.

Quinolone antibiotics (ciprofloxacin, levofloxacin)

Avoid

quercetin inhibits bacterial DNA gyrase weakly; theoretically could affect antibiotic activity (mostly speculative).

High-dose curcumin + quercetin together with iron supplements

Avoid

both are iron chelators; could compound absorption interference. Separate by 2 hours.

Levothyroxine

Avoid

see Drug Interactions; mandatory ≥4-hour separation.

What to Expect

Week 1
Tolerability and dose-response.
Week 2-4
Early effect window.
Week 4-8
Peak benefit assessment.
Week 8+
Cycle decision point.

Side Effects & Safety 7

Side Effects

1Headache — most frequent acute side effect, often at first dose or above 1000 mg. Usually transient.
2GI upset — nausea, gastric discomfort, occasionally diarrhea, mostly on empty stomach or at >1500 mg single dose.
3Tingling in extremities — reported at higher doses; mechanism unclear.
4Dizziness
5Fatigue (community signal — 28 reports in dopamine.club)
6Mild anxiety / sleep disruption (community signal in some users; mechanism unclear, possibly histamine rebound or anti-anxiolytic effect of reduced inflammatory cytokines)
7Reduced appetite

When to Stop

Acute kidney injury at IV-research doses (>1.4 g/m²) — quercetin precipitates renal injury at intravenous doses used in oncology trials. Not a risk with oral supplementation at biohacker doses; flagged for completeness.
Hemolysis in G6PD deficiency — theoretical; quercetin is a pro-oxidant at high concentrations. Caution if known G6PD-deficient.
Hypothyroidism — chronic high-dose, animal data: Quercetin in rats at very high doses suppressed thyroid peroxidase and reduced T4. Not documented in humans at supplement doses, but interferes with levothyroxine absorption (see Drug Interactions).
Iron-overload concern: Quercetin chelates iron — could theoretically worsen iron deficiency in marginal-iron-status individuals (relevant for menstruating women with low ferritin). Hemochromatosis is more nuanced — chelation could be beneficial. Discuss with clinician if either applies.
Avoid in late pregnancy — possible uterotonic effect at high doses; insufficient human data.
Lactation — insufficient data; default to avoid.
First 2 weeks: GI tolerance / headache calibration. If either persists beyond 14 days, switch from aglycone to phytosome (often resolves) or reduce dose.
First 30 days if on levothyroxine: Recheck TSH at 8 weeks to confirm no clinical hypothyroidism creep from absorption interference.
Chronic use: No specific monitoring beyond what an athletic 20yo's annual bloodwork already covers.