Cataplasma Sinapis.—Mustard Poultice.
Related entries: Sinapis Nigra (U. S. P.)—Black Mustard
SYNONYMS: Sinapismus, Sinapism, Mustard cataplasm, Cataplasma rubefaciens.
Preparation.—The British Pharmacopoeia directs 2 ½ ounces of mustard (composed of both ground white and black mustard) to be mixed with 2 or 3 ounces of water (lukewarm). This is to be stirred into a mixture of 2 ½ ounces of linseed-meal, made with boiling water (6 or 8 ounces). Mustard should not be mixed with hot water, and it is altogether probable that, by mixing the above mixture of flaxseed and boiling water, the poultice is rendered less effective on account of the volatilization of a portion of the volatile oil of the mustard. The French Codex simply directs the preparation of 200 Gm. [7 oz. av., 24 grs.] of black mustard-meal, recently prepared, to be mixed with water (scarcely tepid) until a poultice-consistence is obtained. A simple method is to mix flour, or flaxseed, with ground mustard, and mix with sufficient water to form a poultice. Vinegar should not be employed in making mustard poultices.
Action and Medical Uses.—Mustard poultice is powerfully stimulant to the skin, the rubefacient effect being quickly produced, and, if long applied, vesication may ensue. A mustard plaster produces intolerable burning. Gangrenous ulcerations have been produced by the careless and prolonged application of these poultices. The black mustard is stronger than the white, and, as a rule, the former should not be left in contact with the skin longer than 20, nor the latter longer than 30 minutes. Care should be exercised in applying them to children. It is best to have a thin piece of gauze or other fabric between the surface of the poultice and the skin, the hairs of the latter having been previously shaved off (For Uses, see Sinapis. For Mustard plaster, see Charta Sinapis).