Quercetin
Supplements · Antioxidants · Supplement, Typed Supps
A plant pigment studied for antioxidant and allergy effects.
Stage by stage
- Intake (Capsule): Poorly absorbed on its own, similar to curcumin — often paired with bromelain or vitamin C.
- Small intestine (Absorbed): Absorbed with the help of its pairing compound.
- Bloodstream (Brief circulation): Whatever is absorbed circulates with antioxidant activity before reaching immune cells.
- Immune cells (Antioxidant activity): Has antioxidant activity and may stabilize immune cells involved in allergic responses.
What the evidence supports
- Modestly lowering blood pressure at doses of 500 mg/day or more — limited evidence. Several meta-analyses find a small but statistically significant reduction, concentrated at higher doses. The effect is small and limited by quercetin's poor absorption.
- Relieving allergy (allergic rhinitis) symptoms — limited evidence. The rationale is mast-cell stabilisation, but this is largely from laboratory work; human trial evidence is sparse and it does not act like a fast antihistamine.
- Improving exercise performance or reducing illness in athletes — insufficient evidence. Trials have generally shown trivial or no meaningful effect.
Typical dose
500–1000 mg daily in most studies
Upper limit: No established UL; short-term use up to about 1000 mg/day is common, with caution about very high doses
Timing
Ideally with vitamin C.
Time to effect
- Weeks: Any reported allergy-related benefit in studies.
Medication interactions
- Ciclosporin and other immunosuppressants: Quercetin can raise blood levels of ciclosporin and prolong its stay in the body. (moderate)
- Fluoroquinolone antibiotics: Quercetin may compete with these antibiotics and reduce their effectiveness. (moderate)
Common myth
“Quercetin works like an antihistamine.” In reality: Its allergy-related evidence is much weaker and slower-acting than actual antihistamine medication.
Food sources
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