Witch Hazel
In plain terms
A plant astringent in toners, soothing in the right form but a common cause of dryness and irritation in the wrong one. The catch is usually the alcohol: most drugstore witch hazel waters are 14 to 15% alcohol, which dries and irritates, and the plant's own tannins are drying too.
What the evidence shows
Witch hazel is a tannin-rich plant astringent with real anti-inflammatory activity; topical studies show it can calm UV-reddened skin, and a hamamelis ointment performed as well as a dexpanthenol ointment for minor skin irritation in children. So the plant itself is not the problem. The catch is what it usually comes in. The common drugstore witch hazel water is made by distillation with alcohol added, leaving most bottles at roughly 14 to 15% alcohol, enough to dry and irritate skin, especially if it is sensitive, broken, or already inflamed. The tannins that give witch hazel its tightening, pore-shrinking feel are themselves drying with repeated use. Allergic reactions happen but are uncommon, and it is tolerated well by most, including children, in suitable preparations. So the verdict turns on the form and how often you use it: an occasional astringent, or an alcohol-free formula, is fine for many; a daily high-alcohol toner on reactive skin is a recipe for a stripped, irritated barrier. It is also not a proven acne treatment, where benzoyl peroxide, salicylic acid, or azelaic acid have the evidence.
On the label
Listed as witch hazel or hamamelis virginiana. Check whether the product is alcohol-free, since the standard distillate carries 14 to 15% alcohol that does most of the drying. Use it occasionally rather than daily if your skin runs dry or reactive, and do not rely on it as an acne fix.