Horsetail extract concentrates the silica and flavonoids naturally present in the Equisetum arvense plant. Silica supports collagen formation, so people reach for this extract when they want stronger hair, smoother skin, and tougher nails.
Bone and joint upkeep are other common reasons to try it. A mild diuretic effect means the body sheds more water, which some find useful. Capsules or liquid extracts both work. Take it with food to settle the stomach.
Skip horsetail if you take prescription diuretics or lithium, since the herb can amplify their effects. Do not use it during pregnancy or with kidney trouble.