The anthraquinones it contains normally have an intense cathartic effect on the digestive system but in this herb they act in a mild way, possibly moderated by its high tannin content. Thus, Yellow Dock is a valuable curative against constipation, since it does not only stimulate the intestinal muscles but acts in a much wider manner. It promotes the flow of bile and has a secret effect as a blood purifier. Its effect on the gallbladder makes it useful in curing jaundice, when caused by congestion. Yellow Dock is used widely in treatments for chronic skin conditions such as psoriasis.