The leaflets and branches of the indigo plant yield an exquisite blue dye; people around the globe have used it to color textiles and clothing for centuries. Before the development of synthetic blue dyes, indigo was cultivated for this pigment rather than for medicinal use.

In the traditional medicine of India and China, indigo was used in the treatment of conditions we would now call epilepsy, bronchitis, liver disease, and psychiatric illness.1 However, there is no real scientific evidence for any of these uses.

Warning: Several species of indigo are poisonous. See Safety Issues for more information.

Based on its traditional use for liver problems, researchers have investigated whether indigo might protect the liver against chemically induced injury. Animal studies do suggest that extracts of the indigo species Indigofera tinctoriaprotect the liver from damage by toxic chemicals.2,3 No human trials, however, have been performed to examine indigo's effects on the liver.

The species Indigofera oblongifoliahas been tested for its antibacterial and antifungal activity.4 In a test tube trial, this plant showed significant activity against certain types of bacteria and fungi. This research is still in its preliminary stages, so it is too early to tell whether Indigofera oblongifolia will prove useful for the treatment of any infectious diseases.

Note: A different plant called wild indigo ( Baptisia tinctoria), in combination with echinaceaand white cedar, has been studied as a possible immune stimulant.5 However, wild indigo is not part of the Indigofera family of plants and is not discussed here.