This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol2", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
Of the origin, sensible and chemical properties, and various effects and applications of this valuable medicine, there will be occasion to treat under the rubefacients. it is only the emetic property which I propose to notice in this place. Powdered mustard acts with considerable promptness and energy as an emetic. This effect is probably owing to its direct irritant operation on the gastric mucous membrane. At the same time, it has a tendency rather to stimulate than to depress the system at large.
It is then as a stimulating emetic that it is specially characterized; and in this capacity it is usually employed. The cases to which it is peculiarly applicable are those of great torpor of stomach, and general weakness or prostration. When the stomach is quite insensible to ordinary emetics, mustard may be added to them with propriety. Hence its use in narcotic poisoning. it is specially adapted to cases of this kind, in which, either from the time that has elapsed, or the sedative character of the poison, there may be a prostrate state of the system, or such a condition may be apprehended. in the more advanced stages, therefore, of poisoning by opium, and immediately, in poisoning by hydrocyanic acid, digitalis, aconite, tobacco, etc., when there may be an indication for the discharge of the poison, mustard should be employed, either alone or with other medicines. it is also admirably adapted to the cold stage of the pernicious miasmatic fever, and, indeed, to a similar condition at the commencement of any other febrile disease, when the stomach is not already irritable, and there is a strong necessity for rousing the system out of its torpor. it has also been recommended, in the collapse, or approaching collapse of cholera, in order, by a powerful impression upon the gastro-intestinal mucous membrane, to check the exhausting discharges, as well as to produce an exciting effect upon the failing general powers. it may be given, moreover, with a similar view, in some cases of torpor from old paralysis, in which there is no reason to apprehend danger from excitement of the nervous centres, which may have been the original seat of the malady.
The dose of mustard as an emetic is a slightly heaped teaspoonful (about a drachm), thoroughly mixed with six or eight fluidounces of water. The dose may be doubled or tripled in cases of great insensibility of stomach. Copious dilution is desirable, in order to prevent too concentrated an effect on some one part of the mucous membrane. in over-doses, or improperly administered, it may induce gastro-enteritis, with vomiting, purging, etc.