ALTERATIVES, in medicine, a term applied to remedies that have the power of changing the state of the living solids of the body, and consequently altering the func tions which they perform. It is generally applied, however, to medicines which are irritant in full doses, but which almost imperceptibly alter disordered actions or secre tions; acting specially on certain glands, or upon absorption in general, when they are given in comparatively small doses, the treatment being continued for a considerable length of time. For example, mercury is an irritant in some of its preparations ; but when small doses of blue pill, Plummer's pill, or corrosive sublimate are given at inter vals for some length of time, they " produce alteration in disordered actions, so as to cause an improvement in the nutrient and digestive functions, the disappearance of eruptions, and the removal of thickening of the skin or of other tissues" (Hoyle) ; and they will effect these changes without otherwise affecting the constitution or inducing salivation.
So iodine, also an irritant in concentrated doses, and poisonous in some forms, is most useful, when given in small doses, in effecting the removal of elarged glandular organs, and need not cause iodism, if carefully given.
The preparations of gold are likewise stimulants of the absorbents, and are used in cases of scrofula. Some preparations of arsenic are powerful A. in cases of skin-disease. So also are the decoctions of the woods and their substitutes, such as decoction of Sarsaparilla, and the like, which, when taken in large quantities of water, must operate partly by their diluting and solvent properties, and partly by the stimulant effect of the active principles of several ingredients in these diet-drinks, conveyed into the capillaries.
It will be seen, therefore, that the term A. rather implies the method in which some drugs are administered, than any special alterative action possessed by them. The most useful, it may be added, are also the most dangerous in unskilled hands.