Acts especially upon the ramifications of the pneumogastric nerve, producing spasmodic irritation, mostly in the chest and stomach, giving rise in the former to asthma, and in the latter to nausea and vomiting. It also irritates the mucous membranes of the respiratory and digestive tracts, causing catarrhal conditions of these parts, and through the same sources of irritation has the power of producing haemorrhage from mucous surfaces. The principal feature of Ipecac is its persistent nausea and vomiting, which is its chief indication in all diseases. Characteristic symptoms.