For over 2,000 years, they have been used as treatments for mastitis, breast cancer, and a variety of other ailments, as well as a pain reliever. Although caution should be used when eating large quantities of the roots and young shoots for they are known to be toxic. The leaves, when eaten in large amounts, are said to have a mild laxative effect. Root Tea is used as a diuretic. It is also a folk cancer remedy.
Chinese studies indicate that root extracts are antibacterial, and useful against blood flukes.
The roots and young leaf shoots are considered potentially toxic. Reports indicate that the toxin accumulates in the system and adversely effect the eyes, even causing blindness in some cases. Stir-Fried Day Lily Leaves are especially tasty and tender when they are 3 to 5 inches long and still young. These can be simmered or stir-fried in oil or butter, and some people compare the taste to creamed onions. To dry your own, simply string them on a heavy thread and hang in a high, dry place for a week or two until thoroughly dry.