Quercetin is a bioflavonoid that helps control histamine production and also inhibits the action of adhesion molecules. The action of these molecules leads to inflammation commonly associated with an allergic reaction. Reducing histamine significantly reduces over-reactions to allergens.


Ailments / Situations Where Used

Any ailment involving excess histamine production can benefit from quercetin's antihistamine and antiallergenic properties. This includes environmental / seasonal / tree pollen allergies and hay fever.

Quercetin also has anti-inflammatory properties and is useful in treating asthma, bronchitis, chronic obstructive pulmonary disease, common colds, flu, and sinusitis.

Quercetin blocks an enzyme that leads to sorbitol accumulation. As a result, it may reduce problems associated with diabetes, including diabetic cataracts, neuropathy (nerve damage), retinopathy (eye damage), and kidney damage.

Its antioxidant properties help prevent cardiovascular disease by protecting against LDL ("bad") cholesterol.



Quercetin is found mostly in onions, with lower concentrations in apples and black tea. Smaller amounts can be found in leafy green vegetables and beans.


Optimal Absorption

Eat onions and apples regularly. If supplementing, take 250 to 400mg two to three times daily, before meals.

Take with vitamin C for optimal absorption.


Contraindications / Precautions / Warnings

No known toxicity.


Ailment / Situation Listing




Cardiovascular Disease

Chronic Obstructive Pulmonary Disease

Common Cold

Diabetic Cataracts

Environmental/Seasonal Allergies


Hay Fever

Kidney Damage

Neuropathy (Diabetes-Related)

Retinopathy (Diabetes-Related)