The roots, leaves and flowers are antitussive, aperient, diuretic and lithontripic. The root contains a fixed oil that is anti-diuretic and an essential oil that is diuretic. If the diuretic action is required then the root should be infused and not decocted or the essential oil will be evaporated. An infusion is used in the treatment of dropsy, inflammation of the bladder and kidneys, rheumatism and chronic skin disorders. The roots are used occasionally, they are harvested in the autumn, cut into slices and carefully dried for later use. The young shoots are more commonly used, either fresh or dried. They can be harvested throughout the summer. A cough mixture is made from the bark. Source: https://pfaf.org/
Find more about this plant on Wikipedia.