Chinese herbal medicines containing quercetin include Chai Hu, Mulberry Leaf, Sophora, Xuan Fu Hua, and Hawthorn, while Chinese patent medicines include Chai Hu Kou Fu Ye, Chai Hu Shu Gan Wan, Xiao Yao Wan, Bu Zhong Yi Qi Wan, Sang Ju Gan Mao Pian, Di Yu Huai Hua Wan, Hong Guan Yao Pian, Yin Chai Chong Ji, Li Dan Pian, Long Dan Xie Gan Wan, Shan Zha Wan, and Shou Wu Pian.
Quercetin belongs to the flavonoid class and contains multiple phenolic hydroxyl groups and a 5-OH, 4-keto structure in its molecular structure. It can form corresponding complexes with metal ions such as aluminum, calcium, magnesium, iron, and bismuth in western medicines containing metals, such as Bismuth Subgallate Tablets, Gastric Soothing Tablets, Aluminum Hydroxide Gel, Aluminum Sucrose Sulfate, Basic Bismuth Carbonate, Magnesium Trisilicate, Ferrous Sulfate, Calcium Gluconate, Calcium Lactate, and Calcium Carbonate Tablets. These metal-containing complexes are hardly absorbed by the intestines, thus reducing the effectiveness of the drugs. Therefore, the above-mentioned Chinese patent medicines should not be used in combination with western medicines containing metal ions. If it is necessary to use them together, it is best to separate the administration of the Chinese herbal medicines and western medicines by at least two hours to avoid their interaction.
