← Back
3Medicinal

Quercetin

Also sold as Quercetin dihydrate, quercetin phytosome

A plant flavonoid used for allergy, immune, and inflammation support — well studied in the lab, less convincingly in people.

TrustedSupp Tier System™ · Tier 3Take as a defined course
Check before you startThis one has documented interactions with medication classes where the consequences are serious. If you take any prescription medicine, run it past a pharmacist before starting.

Evidence strength

35/100Limited
WEAKLIMITEDMODERATESTRONGVERY STRONG

What the evidence supports: allergy symptoms and exercise recovery markers in small trials.

This scores how well-supported the claim above is — not how much benefit you personally would get. A high score on a narrow claim does not extend to everything the product is marketed for.

How long to take it

Short courses, for example through allergy season. Continuous long-term use is not well studied.

Who it's actually for

People exploring allergy or post-exercise inflammation support, with modest expectations.

Safe upper limit

Unverified
No formal upper limit; 500–1,000 mg daily in most trials
Generally well tolerated at studied doses. At higher doses it can inhibit drug-metabolising enzymes, raising blood levels of some medications.
No source or citation attached yet.

Interactions to know about

Run your full list through the interaction check.

Practical notes

  • Standard quercetin absorbs poorly; phytosome forms improve this.
  • Can change levels of some drugs, including certain antibiotics and immunosuppressants — check with a pharmacist.
  • Onions, apples and capers are dietary sources at far lower doses.