It is also called the wooly foxglove because of the furry texture of its flower petals. It is a very important medicinal plant grown commercially for the cardiac glycoside digoxin. Lanoxin (digoxin) is used in the treatment of chronic congestive heart failure alone or in combination with other drugs prescribed for the same purpose. Digoxin is also used in the treatment of certain cardiac arrhythmias. Digoxin was first isolated from the other cardiac glycosides in 1930. Digoxin has recently been found to be active against T helper cells that contribute to the development of autoimmune diseases.
Nearly all members of the genus Digitalis are medicinal plants in that they contain the cardiac glycosides in their leaves, stems, and flowers. Digitalis purpurea is the plant in which the cardiac therapeutic properties of these plants were found originally. The digitalis plant of greatest importance in the 21st century is Digitalis lanata; it is the source of digoxin (Lanoxin).