The fresh herb has a sharpish, peppery taste. The peppery taste and the fact that this herb like to grow in damp places and by streams are responsible for the alternative name waterpepper. When meat was being butchered, Amish farmers burned this herb in pots to keep away flies. It has been used to dye wool yellow. It was formerly much esteemed for this purpose in rural Louisiana, where it was called Culrage.
Water pepper is a vasoconstrictor.
The flowering heads and leaves are mostly used but occasionally the fresh roots too. Principally it is used as an infusion to stem bleeding and relieve menstrual pain. A cold water infusion used to be prescribed for gravel, dysentery, coughs, sore throats, colds, and gout. A fomentation is good for chronic ulcers and bleeding tumors. Some of the old herbalists thought it effective in nervous diseases like vertigo, lethargy, apoplexy and palsy.