What is the recommended dosage for Quercetin?

General: 500-1,000 mg/day; Immune Support: 500-1,500 mg/day

What are the side effects of Quercetin?

Potential side effects include: Headache, Tingling in extremities, Gastrointestinal discomfort, Low oral bioavailability (addressed by phytosome formulations).

What is quercetin and how does it support the immune system?

Quercetin is a flavonoid found in onions, apples, and berries. It has been studied for its antioxidant and anti-inflammatory properties, including its ability to inhibit pro-inflammatory cytokines and stabilize mast cells involved in allergic immune responses.

What dosage of quercetin has been studied for immune health?

Clinical trials have used quercetin at doses of 500–1,000 mg per day, often co-administered with vitamin C or bromelain to enhance absorption. Study durations range from 2 to 12 weeks depending on the outcome measured.

What are the potential side effects of quercetin?

Quercetin is generally well tolerated at doses up to 1,000 mg per day. High doses may cause headache, tingling, and gastrointestinal discomfort. Quercetin may interact with certain antibiotics and cyclosporine by affecting drug metabolism.

Quercetin

antioxidant

Also known as: Quercetin Dihydrate, Isoquercetin, Quercetin Phytosome

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About

Quercetin is a flavonol polyphenol with antioxidant, anti-inflammatory, and immunomodulatory properties. It inhibits mast cell degranulation and histamine release, modulates NF-kB and NLRP3 inflammasome pathways, and may act as a zinc ionophore to enhance intracellular zinc uptake. GRAS-designated by the FDA.

How It Works

Flavonol polyphenol that inhibits mast cell degranulation and histamine release; modulates NF-kB and NLRP3 inflammasome pathways; may support zinc ionophore activity to enhance intracellular zinc uptake.

Evidence For Conditions

Condition	Grade	Studies	Participants
Allergic Rhinitis	C	5	400	View →

Side Effects

Headache
Tingling in extremities
Gastrointestinal discomfort
Low oral bioavailability (addressed by phytosome formulations)

Drug & Supplement Interactions

Cyclosporine (may increase drug levels)
Fluoroquinolone antibiotics (may interfere with bacterial target)
CYP3A4 and CYP2C8 substrates (may inhibit metabolism)

Always inform your healthcare provider about all supplements you take.

Related Ingredients

Astaxanthin Curcumin Glutathione Resveratrol

Quick Facts

Dosage: General: 500-1,000 mg/day; Immune_Support: 500-1,500 mg/day
Forms: capsule tablet powder
Natural Sources: Onions, Apples, Berries, Capers, Broccoli, Red wine, Green tea
Upper Limit: No established UL; GRAS up to 500 mg/day per FDA
Best Time: With meals (fat-containing meals improve absorption); often paired with vitamin C or bromelain for enhanced bioavailability

Evidence Summary

Allergic Rhinitis C

FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products and information on this website are not intended to diagnose, treat, cure, or prevent any disease. The evidence grades presented are based on our analysis of published peer-reviewed research and do not constitute medical advice. Always consult your healthcare provider before starting any supplement regimen.