Indigo - western medicine

Although traditional Asian cultures use indigo to treat a wide range of medical conditions, the species is not generally used by western medical herbalists and as yet there is little clinical evidence to support indigo's effectiveness.

Properties

Studies at an early stage indicate alcohol extracts from leaves and stems protect the liver from certain kinds of chemical damage such as that from carbon tetrachloride, often found in cleaning agents, aerosols and refrigerants. These extracts also show the ability to lower blood pressure, while the compound indigotin, the source of the plant's blue dye, may have antiseptic and astringent properties.

Studies of Chinese medicinal plants show that a different compound, indirubin, may have anticancer properties, which are currently under further investigation.

Extracts of indigo leaves contain compounds called rotenoids, with insecticidal properties against mosquito larvae.

Safety

A compound called indican, a glucoside known to be carcinogenic, is present in significant amounts throughout the plant. Although there are no reports of poisoning, indigo is unlikely to be a safe medicinal plant. This is borne out by a report from 1836 of its use in treating epilepsy: "Shortly after taking it, the patient experiences a sense of constriction at the fauces, and the impression of a metallic taste on the tongue. These are followed by nausea, and frequently by actual vomiting.........In some the vomiting is so violent as to preclude the further use of the remedy. The matter vomited presents no peculiarity except its blue colour. When vomiting has subsided, diarrhoea usually occurs: the stools are more frequent, liquid, and of a blue or blackish colour.........frequently accompanied by cardialgia and colic. Occasionally these symptoms increase, and the use of the remedy is in consequence obliged to be omitted."

This information is provided for general interest only. It is not intended as guidance for medicinal use. Further information on using herbal medicines is available.