The wood Picrasma excelsa, a tree of Jamaica.

The active principle, quassin, is an intensely bitter neutral substance.

Quassia is one of the most active of simple bitters and stomachics. It contains no tannin, and is therefore not incompatible with iron.

An infusion of quassia used as an enema is anthelmintic.

Preparations

Tinctura Quassiae. Tincture Of Quassia

Strength, 20%. Average dose,  xxx.-2 mils. An infusion of quassia is considered effective and not harmful to the patient in treatment for thread worms. It is preceded by a soap and water enema, and is then given high and retained for some minutes.