BLISTERS (akin to 0. Dutch bluyster, blis ter; cf. blast, blow). .Medicinal agents which, when applied to the skin. raise the cuticle into small vesicles filled with serous fluid. They are applied either in the form of plasters or in a fluid state, as suits the convenience of the per son or part, and have for their object the estab lishing of a counter-irritation or diversion of morbifie action from a part in which it cannot be reached by remedies, or from sonic organ where it may do permanent mischief, to some more superficial part of the body. The most com mon blister in use is made of eantharides (see BLISTER-BEETLE) mixed with a convenient pro portion of lard and wax to form the blistering ointment of ordinary use. If applied too long it produces distressing affection of the urinary blad der, and may produce sores which are difficult to heal. Four hours are generally requisite to pro duce the desired effect. Mustard (Sinapis nigra) is frequently used, but seldom left on sufficiently long to produce blistering. Its effect may be
limited by applying white of egg to the blistered surface. Croton-oil, strong liquor ammonite. tar tar-tfbetic ointment, and many others, are used iu practice. If the occasion for the blister passes off, the vesicles should be opened freely, and thetr fluid contents allowed to escape, the vesicated surface being then dressed with some cold cream or lard. But if it should appear desirable to promote a discharge from the skin, the raised cuticles may be snipped oft, and the blister either applied again at intervals, or sonic stimulating ointment, as ravine ointment, should lie used. Blisters are especially useful in inflammations of serous membranes, as pleurisy, in glandular tumors, in indolent ulcers. and for the relief of muscular pain, as well as for old joint affections.
The term blisters is also commonly applied to elevations of time cuticle filled with serum or blood.