Quercetin is a bioflavonoid similar to rutin. Human cell culture studies with quercetin demonstrated its capability to inhibit the release of histamines. NutraDrops Quercetin provides quercetin in a liquid base that is easily absorbed. Other Ingredients: purified water, fructose, glycerin, lactic acid, natural orange flavor, xanthan gum, lauric arginante, lecithin, stevia extract, and potassium benzoate. Source Naturals was created in 1982 to support each individual's potential to enjoy optimal health. Source Naturals' comprehensive Bio-Aligned Formulas help bring the power of alignment to your body. When formulating, we evaluate the underlying causes of system imbalances, and then provide targeted nutrition to interdependent body systems. Our line of more than 600 products also includes well-researched, single entity nutrients in their highest quality and most bioavailable forms.