EMETICS are substances given for the purpose of producing vomiting. It is customary to divide emetics into central, those which act on the vomiting centre in the medulla, and gastric, those which act directly on the stomach itself. The gastric emetics in common use are alum, ammonium carbonate, zinc sulphate, sodium chloride (common salt), mustard, and warm water. The central emetics are apomorphine, tartar emetic, ipecacuanha, senega, and squill. Of these, tartar emetic and ipecacuanha come under both heads ; when taken by the mouth they act as gastric emetics before absorption into the blood, and later produce a further and more vigorous effect by stimulation of the medullary centre. Their action is accompanied by intense depression.
Emetics have two main uses : that of emptying the stomach, especially in cases of poisoning, and that of clearing the air pas sages, more especially in children. Where possible the first of these is nearly always replaced by use of the stomach pump, whereby depression is avoided. Emetics still have their place, however, in the treatment of bronchitis, laryngitis, and diphtheria in children. Occasionally also they are administered when a foreign body has entered the larynx.