One medical study, using large amounts of gentian violet in rats, found that it could cause cancer.
When the secretion of gastric juice is deficient it may be excited by gastric tonics, such as ten grains of bicarbonate of soda and a drachm of compound tincture of gentian in water shortly before meals, and may be supplemented by the administration of pepsin and hydrochloric acid after meals.
Gentian violet, a purple dye, used to be a common remedy.
Although cancer from gentian violet has not been observed in humans, some doctors choose not to recommend it for this reason.
The bitterness is imparted by such substances as bitter orange rind, gentian, rhubarb, quassia, cascarilla, angostura, quinine and cinchona.