精油
The main phytochemicals in witch-hazel leaves are polyphenols, including 3–10% tannins, flavonoids, and up to 0.5% essential oil, while the bark has a higher tannin content. Hamamelis water, also called "white hazel" or "witch hazel water" prepared from a steam-distillation process using leaves, bark or twigs, is a clear, colorless liquid containing 13–15% ethanol having the odor of the essential oil, but with no tannins present. Essential oil components, such as carvacrol and eugenol, may be present.