Quercetin

INCI: Quercetin | Function: Antioxidant, Anti-inflammatory | Type: Polyphenol (flavonoid)

What Is Quercetin?

Quercetin is a flavonoid antioxidant found widely in fruits and vegetables (apples, onions, berries, tea). It is one of the most potent natural antioxidants and also acts as a mast cell stabilizer, reducing histamine release — making it valuable for sensitive and allergy-prone skin.

Key Skin Benefits

+ Potent antioxidant (one of the strongest flavonoids)
+ Mast cell stabilizer — reduces histamine-driven inflammation
+ Protects collagen from MMP degradation
+ Anti-inflammatory for sensitive/reactive skin
+ Synergistic with Vitamin C (recycles it)

Pros

+ Natural, widely consumed flavonoid
+ Dual antioxidant + anti-inflammatory action
+ Mast cell stabilizing effect unique among flavonoids
+ Extensive human safety data (dietary flavonoid)
+ Synergizes with Vitamin C and E

Cons

− Poor water solubility — difficult to formulate
− Oxidizes and turns brown in formulations
− Bright yellow color can tint products
− Limited skin penetration without enhancers
− Photosensitive

Specifications

Property	Value
Usage Areas	Face, Eye, Body
Product Type	Leave-On, Rinse-Off
Source	Plant (apples, onions, tea)
Natural Level	Natural

Safety Ratings

Metric	Rating
Skin Sensitivity	0/5 (none)
Comedogenic Rating	0/5
EWG Score	1/10

Regional Regulatory Limits

Region	Leave-on %	Rinse-off %	Status
EU (CosIng)	No limit	No limit	Allowed
US (CIR/FDA)	No limit	No limit	Allowed — GRAS
Japan (MHLW)	No limit	No limit	Allowed
ASEAN	No limit	No limit	Allowed
China (NMPA)	No limit	No limit	Allowed

Typical Usage % by Product Type

Product Type	Typical %
Antioxidant serum	0.05 - 0.5%
Soothing cream	0.05 - 0.2%
Eye treatment	0.01 - 0.1%

References

Hatahet T et al. (2016) — Quercetin topical delivery. PMID: 27240328
Maramaldi G et al. (2016) — Quercetin in skin care. PMID: 26492442
EWG Skin Deep — Score 1/10

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