Yarrow has been explored most prominently as a treatment for wounds and general skin/membrane inflammation. More specifically, yarrow has been studied for: healing in oral mucositis produced as a side effect of chemotherapy,[1][2] episiotomy,[3] leishmaniasis lesions,[4] vaginal irritations/infections,[5][6] gingival inflammation,[7] tonsillitis,[8] nipple cracking during breastfeeding,[9] and atopic dermatitis.[10] In these studies, yarrow was most often applied topically, but whenever it’s applied to mucosal membranes (i.e., when applied orally or vaginally) it could potentially have systemic effects too.
Where wound healing is concerned (oral mucositis, episiotomy, nipple cracking, and leishmaniasis lesions), topical application of yarrow seems promising for healing oral mucositis (15 ml solution, 4x per day for 14 days), nipple cracking (30 g yarrow plus 1 liter water breast wash, twice per day for 7 days), and vaginal episiotomy (5% ointment in 30g tube, applied 2x per day for 10 days), but was ineffective for lesions caused by leishmaniasis infection.[1][2][3][4][9]