Quercetin at a glance

  • Occurs naturally in red wine (grapes), tea, kale, tomatoes, and berries
  • Antioxidant, skin-soothing, and restorative ingredient
  • Present in St. John’s wort and Ginkgo biloba

Quercetin description

Quercetin is a bioflavinoid ingredient from plants. It occurs naturally in grapes (so it is also found in red wine), tea, onions, kale, tomatoes, berries, and many other fruits and vegetables, with the highest concentrations found in the leaves and skins. It functions as an antioxidant, skin-soothing agent, and restorative ingredient. In terms of skin care, research has shown that a lipid-based (fat-based) delivery system is optimal for quercetin to exert antioxidant benefits. Even more exciting, this type of formula provides an initial burst of quercetin followed by sustained release over a 24-hour period. When quercetin is mixed with silicone and lipids, the intake is greater, as confirmed by testing on human skin. Emerging research also shows quercetin has protective effects against ultraviolet-B (UVB) radiation, though quercetin is not approved as an active sunscreen ingredient. Higher amounts of quercetin impart a pale yellow to golden colour to cosmetics.

Quercetin references

  • Current Medicinal Chemistry, September 2019, pages 5,825-5,848
  • Frontiers in Phamacology, July 2018, page 826
  • Pharmacognosy Review, July–December 2016, pages 84–89
  • International Journal of Nanomedicine, May 2016, pages 1,987-2,007
  • International Journal of Pharmacology, January 2013, issues 1-2, pages 56-66
  • Skin Pharmacology and Physiology, 2013, issue 2, pages 57-67

Peer-reviewed, substantiated scientific research is used to assess ingredients in this dictionary. Regulations regarding constraints, permitted concentration levels and availability vary by country and region.

Ingredient ratings


Proven and supported by independent studies. Outstanding active ingredient for most skin types or concerns.


Necessary to improve a formula's texture, stability, or penetration.


Generally non-irritating but may have aesthetic, stability, or other issues that limit its usefulness.


There is a likelihood of irritation. Risk increases when combined with other problematic ingredients.


May cause irritation, inflammation, dryness, etc. May offer benefit in some capability but overall, proven to do more harm than good.


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Not rated

We have not yet rated this ingredient because we have not had a chance to review the research on it.