Home / Ingredient Directory / Quercetin
Yannis Lopez
Reviewed by Yannis Lopez · Nutrition Industry Veteran
Last updated: July 6, 2026
Antioxidant & Immune Flavonoid

Quercetin

Antioxidant & immune support

Found in onions, apples, berries
Often stacked with Vitamin C

FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Always consult your physician before starting any supplement.

Overview

Quercetin is a naturally occurring flavonoid antioxidant found in many fruits, vegetables, and grains — especially onions, apples, berries, and green tea. It is known for its antioxidant, anti-inflammatory, and immune-supporting properties.

Quercetin has gained significant attention in recent years for its potential to support immune function and act as a natural antihistamine. It is often stacked with Vitamin C and Bromelain for enhanced absorption and synergistic effects.

Potential Benefits

Antioxidant Support

Neutralizes free radicals and supports the body's natural antioxidant defenses. One of the most studied flavonoids.

Immune Support

May support healthy immune function, especially when combined with Vitamin C and Zinc.

Allergy & Histamine Support

Often used as a natural antihistamine. May help support a healthy histamine response.

Generally Well Tolerated

Quercetin is very safe at recommended doses. Some people may experience mild stomach upset at very high doses.

Typical Dosage
Daily Dose
500–1,000mg
Often taken with Vitamin C or Bromelain
Best Taken
With meals containing fat
Absorption is improved when taken with food
Pro Tips
  • Stack with Vitamin C for enhanced immune support
  • Bromelain may improve absorption
  • Take consistently for best results
  • Look for quercetin dihydrate or phytosome forms
Research Snapshot

Quercetin has been studied for its antioxidant, anti-inflammatory, and immune-modulating properties. A randomized trial found that physically fit older adults taking 1,000mg/day experienced significantly fewer and less severe upper respiratory tract infections than placebo.

How Quercetin Compares

Ingredient Best For Key Difference
Quercetin Antioxidant, Immune, Allergy Flavonoid; often stacked with Vitamin C
Vitamin C Immune support, Antioxidant, Collagen Water-soluble; excess is excreted
Turmeric / Curcumin Joint comfort, Inflammation Plant compound; needs enhanced absorption

Quercetin is often stacked with Vitamin C and Zinc for comprehensive immune support.

Popular Stacks with Quercetin
Immunity Stack
Quercetin + Vitamin C + Zinc
Most popular immune support combination
Allergy & Respiratory Stack
Quercetin + Bromelain + NAC
Popular during allergy season
Antioxidant Stack
Quercetin + Alpha Lipoic Acid + Vitamin C
Great for comprehensive antioxidant support

Full stack recommendations coming soon in our Stacks section.

Frequently Asked Questions
How long until I feel benefits?
Some people notice benefits within a few days to a week. For immune and antioxidant support, consistent daily use for 2–4 weeks is recommended.
Can I take Quercetin with Vitamin C?
Yes. Quercetin and Vitamin C are commonly stacked together. Vitamin C may help improve quercetin absorption, and they work synergistically for immune support.
Is Quercetin the same as quercetin dihydrate?
Quercetin dihydrate is a common, well-absorbed form of quercetin used in supplements. It is the standard form found in most quality products.
Sources & References
  1. Heinz SA, et al. Quercetin supplementation and upper respiratory tract infection: A randomized community clinical trial. Pharmacol Res. 2010;62(3):237–42.
  2. Boots AW, et al. Health effects of quercetin: from antioxidant to nutraceutical. Eur J Pharmacol. 2008;585(2–3):325–37.
  3. Mlcek J, et al. Quercetin and its anti-allergic immune response. Molecules. 2016;21(5):623.
Related Ingredients
Vitamin C Resveratrol Pine Bark Extract Turmeric
From the Blog
Supplement Timing: What Actually Matters 7 Supplement Myths That Will Not Die Why “Natural” Does Not Mean Safe
Back to Ingredient Directory
Get Your Free Supplement Guide

Evidence-based supplement recommendations from a former physical store owner. No hype. No BS. Just facts.

Download Free PDF