Description Yarrow is a plant that has been used for centuries in traditional medicine. It is also commonly known as achillea, bloodwort, carpenter's weed, devil's nettle, nosebleed, old man's pepper, staunchweed, thousand-leaf, and wound wort (among other names). But, does it work for the wide variety of elements it's been used to treat? As is common with herbal supplements, we don't yet have enough research to say for sure. However, preliminary studies do show promise for this herb in multiple areas. The flowering portion of the yarrow plant is what is typically used for medical purposes. Yarrow isn't just a single plant, though—the name is applied to about 140 different but closely related varieties that fall into the genus Achillea. Yarrow plants have been researched for a wide range of health problems and ailments that it has been traditionally used for. The following uses all have some studies associated with them. However, most of them have been performed on animals or on cells. Human trials, so far, have been rare. That means research is in its early stages and the findings have to be replicated in larger and more in-depth studies before we know for certain what medicinal benefits yarrow has—and how safe a treatment it is.