Catechu is an extract of any of several species of Acacia – but especially Acacia catechu – produced by boiling the wood in water and evaporating the resulting brew. Catechu is an astringent and has been used since ancient times in ayurvedic medicine as well as in breath-freshening spice mixtures. Also called cutch, it is a brown dye used for tanning and dyeing and for preserving fishnets and sails. White cutch, also known as gambier, gambeer, or gambir, has the same uses.
Catechu is widely used as a component of the betel leaf chewed in India. It is used for the local treatment of otitis and otorrhoea. It is also useful in dental, oral, throat and tonsillar infections, and as an astringent for reducing oozing from chronic ulcers and wounds. The extract is also used in dermatoses – locally and systemically.