Flavonoid
Quercetin (Immune)
Also known as: Quercetin dihydrate, Isoquercetin, Quercetin phytosome
Flavonoid with broad antiviral activity, zinc ionophore function, and anti-inflammatory properties.
Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.
Every Quercetin (Immune) product we have scored
| # | Product | Score | Per serving |
|---|---|---|---|
| 1 | Thorne Quercetin Phytosome | 92 A | $0.77 |
| 2 | Thorne Quercetin Complex | 90 A | $0.90 |
| 3 | Thorne Advanced Nutrients | 88 A | $2.40 |
| 4 | Thorne Pre-Workout Elite | 88 A | $1.83 |
| 5 | Thorne PolyResveratrol-SR® | 87 A | $1.97 |
| 6 | Nutricost Quercetin (1000mg) | 87 A | $0.37 |
| 7 | Pure Encapsulations PureDefense with NAC | 87 A | $1.90 |
| 8 | Pure Encapsulations Quercetin | 86 A- | $0.97 |
| 9 | Pure Encapsulations NeuroPure | 86 A- | $1.18 |
| 10 | Jarrow Formulas Quercetin | 86 A- | $0.34 |
| 11 | Pure Encapsulations A.I. Formula | 85 A- | $0.61 |
| 12 | Thorne ResveraCel | 84 A- | $2.00 |
Scored on dose accuracy, form, label transparency and third-party testing. Per-serving cost is list price divided by servings per container. No brand pays to be listed or ranked.
Common questions
How much Quercetin (Immune) should I take?
The typical range is 500-1000mg 2-3x daily. During illness or ongoing for allergies
When should I take Quercetin (Immune)?
With meals and zinc. Yes, enhances absorption.
Which form of Quercetin (Immune) is best?
Quercetin phytosome — Enhanced absorption. Other forms in the catalog: Quercetin dihydrate, Isoquercetin, With bromelain.
Is Quercetin (Immune) safe?
Commonly reported: GI upset, Headache. Serious warnings: May affect thyroid function at very high doses. Caution at high doses with kidney issues
Which Quercetin (Immune) supplement scores highest?
Thorne Quercetin Phytosome, at 92/100. Scored on dose accuracy, form, label transparency and third-party testing — no brand pays to be listed or ranked.
Primary uses
- Antiviral
- Anti-inflammatory
- Zinc ionophore
- Allergy relief
How it works
- Helps zinc enter cells (ionophore)
- Inhibits viral replication enzymes
- Anti-inflammatory effects
- Mast cell stabilization
Dosage
- Typical range
- 500-1000mg 2-3x daily
- Timing
- With meals and zinc
- With food
- Yes, enhances absorption
- Duration
- During illness or ongoing for allergies
- Special populations
- Those seeking antiviral or allergy support
Forms
- Quercetin phytosome
- Quercetin dihydrate
- Isoquercetin
- With bromelain
Safety
Common side effects
- GI upset
- Headache
Contraindications
- Kidney disease (high doses)
Products containing Quercetin (Immune)
Top-scoring supplements in our catalog that list Quercetin (Immune) on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
Evidence notes
Promising research for viral infections
Grade B: Some human trials support key claims; further confirmation needed.
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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.