The dried root of Polygala senega, of the Middle and Southern United States. The active principle is saponin, a glucoside, allied to digitonin, one of the active principles of digitalis.
Senega acts upon the bronchial mucous membrane as a stimulant expectorant and also stimulates the skin and kidneys, increasing the amount of urine and its solid constituents. It is not readily absorbed by the stomach. Small doses impair digestion, and large ones irritate the stomach and intestines, causing nausea, vomiting, and diarrhoea.
Average dose, xv.-I mil.
Average dose,ʒ i-4 mils.