Quercetin is a plant-based flavonoid found in many fruits and vegetables. It has antioxidant and anti-inflammatory properties and is also available as a dietary supplement.

What are the main benefits of quercetin?

Quercetin may help reduce oxidative stress and support a healthy inflammatory response. It is also commonly used for cardiovascular support and seasonal allergy symptoms, though human evidence varies by outcome.

What is a typical quercetin dosage?

Common supplemental amounts are 500–1000 mg per day. Individual needs can vary based on the product and health goals.

Which foods are high in quercetin?

Quercetin is abundant in onions, apples, berries, and other fruits and vegetables. Dietary intake varies depending on food choices and preparation.

Is quercetin safe and are there interactions?

Quercetin is generally well tolerated for many people when used as directed, but side effects can occur. It may interact with some medications, so check with a healthcare professional if you take prescription drugs or have medical conditions.

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Quercetin

Moderate study situation·7/10

A higher score indicates better study conditions, but not necessarily effectiveness.

Quercetin is a plant-based antioxidant flavonoid that may support cardiovascular, immune, and inflammatory health.

Longevity Anti-inflammatory Cardiovascular Support Antioxidant Immune Booster Respiratory Health

dose range

500–1000 mg

Split into two doses taken with meals for best absorption.

Consumption

Take with meals, preferably divided between morning and second meal. Consider formulations that contain bromelain or vitamin C to enhance absorption.

Not fat-soluble.

Best time

Absorption is optimized when taken with food.

Description

Quercetin is a naturally occurring flavonoid abundant in onions, apples, berries, and other fruits and vegetables. It exhibits notable antioxidant and anti-inflammatory effects and is available in supplemental form for targeted health support.

benefits

Main effects with level of evidence

Moderate

Note on evidence

Evidence from observational and interventional studies suggests possible benefits for inflammation, cardiovascular, and immune health, but more high-quality clinical trials are needed, especially for specific indications.

Antioxidant Activity

Moderate

Quercetin acts as a potent antioxidant, reducing oxidative stress by neutralizing free radicals, which may decrease the risk of chronic diseases.

Particularly relevant for: adults · older adults · individuals at risk for chronic diseases

1 · WebMD 2 · Healthline 4 · PMC (Review Article)

Anti-inflammatory Effects

Moderate

Quercetin has been shown to reduce biomarkers of inflammation in some studies, potentially easing symptoms of inflammatory conditions such as allergies and arthritis.

Particularly relevant for: adults with inflammation · individuals with allergies

1 · WebMD 3 · Mount Sinai 4 · PMC (Review Article)

Supports Cardiovascular Health

Moderate

Quercetin supplementation may lower blood pressure and improve endothelial function, contributing to cardiovascular protection.

Particularly relevant for: adults · those with hypertension risk

1 · WebMD 2 · Healthline 4 · PMC (Review Article)

Potential Allergy Relief

Limited

Quercetin may help manage allergy symptoms by inhibiting histamine release and modulating immune responses, but supporting evidence in humans is limited.

Particularly relevant for: individuals with seasonal allergies

1 · WebMD 3 · Mount Sinai

Mild Immune Support

Limited

Quercetin may support immune function, especially during respiratory infections, though data from human trials are limited.

Particularly relevant for: immunocompromised individuals · general population

2 · Healthline 4 · PMC (Review Article)

Safety & Information

Important safety information & known risks

For educational purposes only • not medical advice

Generally well-tolerated at doses ≤1,000 mg/day, but higher doses may cause adverse effects. Safety in pregnancy and lactation is not established.

warning notices

High doses may cause headaches or stomach upset.
Case reports of kidney injury in susceptible individuals.
Avoid use if you have known kidney disease or kidney dysfunction.
Do not use quercetin supplements during pregnancy or breastfeeding due to insufficient safety data.
Use caution and consult your healthcare provider if you take blood thinners (e.g., warfarin), antibiotics (e.g., fluoroquinolones), or chemotherapy drugs, as quercetin may interact with these medications.

Known interactions with medications

Blood thinners (warfarin, apixaban)
Antibiotics (fluoroquinolones)
Chemotherapy agents

Contraindications / special precautions

Pregnancy
Breastfeeding
Known kidney disease or dysfunction

interactions

Important interactions between active ingredient ↔ supplement / medication / food

Quercetin may interact with enzyme-metabolized drugs such as blood thinners, some antibiotics, and chemotherapy agents. It may also have mild interactions with other supplements that affect antioxidant or drug metabolism pathways.

Quercetin may interact with blood thinners like warfarin and increase bleeding risk.

drug · warfarin

MonitorLimited

Why

Quercetin can inhibit cytochrome P450 enzymes, affecting the metabolism of warfarin and potentially increasing its anticoagulant effect.

recommendation

Monitor for increased bleeding and consult your healthcare provider before combining quercetin with warfarin or similar drugs.

1 · WebMD 3 · Mount Sinai

Quercetin may reduce absorption and effectiveness of some antibiotics like fluoroquinolones.

drug · fluoroquinolone antibiotics

AvoidLimitedSeparate by 2–4h

Why

Quercetin can chelate metal ions, reducing absorption of these antibiotics in the gastrointestinal tract.

recommendation

Avoid taking quercetin supplements within 2–4 hours of fluoroquinolone antibiotics.

1 · WebMD 3 · Mount Sinai

Quercetin may interfere with the effectiveness of some chemotherapy drugs.

drug · chemotherapy drugs

CautionLimited

Why

Quercetin may alter the activity of enzymes involved in drug metabolism, potentially impacting chemotherapy efficacy or toxicity.

recommendation

Use quercetin supplements only under medical supervision during chemotherapy.

3 · Mount Sinai

mechanisms of action

Brief explanations of how it works

Free Radical Scavenging

Quercetin donates electrons to neutralize reactive oxygen species, protecting cellular structures from oxidative damage.

2 · Healthline 4 · PMC (Review Article)

Inhibition of Inflammatory Pathways

Quercetin inhibits nuclear factor-kappa B (NF-κB) and cytokine production, reducing inflammation.

3 · Mount Sinai 4 · PMC (Review Article)

Sources & References

Primary literature and reviews on which these statements are based

6 sources

Last updated: March 11, 2026

This information is for educational purposes only and does not replace medical advice.