Sapindus is a genus of about 12 species of shrubs and small trees in the Sapindaceae (soapberry family). Also known as soap-nut tree, its fruits are called Reetha, soap nut, soap berry and wash nut. It is one of the most important trees of the tropical and subtropical regions of Asia.

Soapnuts from the Sapindus mukorossi tree have the highest saponin content. Soapnuts traditionally used as hair shampoos are today an eco-friendly alternative to detergent chemicals. Due to their gentle insecticidal property soapnuts have been used for removing head lice. Recent studies have also reported the tumor cell inhibiting activity of soap nut saponins. They have been used for varied medical conditions as an expectorant, emetic and contraceptive and for relief from migraine.

Cosmetic use

Traditionally in India it is used as a shampoo by bruising the whole nuts which are soaked in warm water. The foamy liquid is then pressed out by squeezing and applied on the hair. It lathers richly and is considered an ideal hair wash preferably after an oil massage on the hair. Dried powder is also used either singly or along with shikakai, fenugreek and fragrant herbs.

Main chemical components are saponins, sapindoside A and B, kaempferol, quercetin, B-sitosterol, palmitic, stearic, oleic, linoleic and eicosenoic acids and glycerides.

Sapindus trifoliatus popularly known as three-leaf berry is the South Indian soap nut.