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.
Applied to the surface of the body, in the form of a cataplasm, or that of a liquid impregnated with its active properties, Cayenne pepper causes a burning pain with inflammation, and, if the surface of application be considerable, a decided stimulant impression on the system generally. it very seldom occasions vesication, and I have never known sloughing to result from it. On the contrary, it seems to be possessed of properties, which render it specially useful in inflammations with a sloughing tendency, at least as this condition is exhibited in the fauces, in malignant sore-throat and scarlet fever. Though generally less powerful, it is safer than mustard; and there is one condition, in which I have seen it, when accompanied with heat in its application, more efficient in exciting the surface and the system than even that energetic rubefacient. The condition alluded to consists in coldness and paleness of the surface, united with more or less comatose insensibility. in low states of the system in typhus and malignant fevers, and in the prostration following the immediate effects of the narcotic poisons, it is an excellent remedy. it should, in such cases, be mixed with heated brandy, and, by means of flannels wrung out of the mixture, should be applied extensively to the extremities, and often also to the trunk of the body, as hot as may be consistent with the safety of the skin. it is much used also as a stimulant in subacute and chronic rheumatism; but I am always fearful of applying local repellent remedies in the former of these affections. its use as a gargle in the sore-throat of scarlet fever, and as an external irritant in the forms of that disease with insufficient eruption, has already been mentioned. A cataplasm made with heated spirit may be applied to the sides of the neck, over the parotids, in the same affection. The powder, thickly sprinkled upon the inside of stockings, has sometimes proved useful in the habitual cold feet of dyspepsia. The officinal tincture is occasionally serviceable in chilblain, and in cases of relaxed uvula, applied by means of a hair pencil directly to the part.