The leaves or the roots of the dock plant are used to make a tea to wash skin ailments. Ruth Welsh said,
Dock is…used for making...a poultice...out of the root and [applied]...on sores that won't heal.
Ruth Welsh said Mrs. Annie Henry from the Yukon would make a tea out of the roots of this plant to bathe rashes or open sores.
Source: Andre, Alestine, Nan t'aih nakwits'inahtsìh (The Land Gives Us Strength) (2006)