This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
The value of phosphorus in these maladies was mentioned by Cazenave, and in 1850 Burgess recommended it in psoriasis and in lupus. More recently Dr. Broadbent, inquiring how far the chemical analogies of drugs would guide to their therapeutical effect, was led to use phosphorus in the same class of cases as arsenic, and he recorded six cases of eczema and six of psoriasis treated by the former drug. The majority of these were relieved or cured ("Clinical Society's Transactions," vol. iv.).
Dr. Eames also reported successful cases under the same treatment (Dublin Journal, January, 1872), and Mr. Squire, recording in detail the course of psoriasis in a young girl, to whom full doses (1/10 to 2/5 gr. per diem) were given for several weeks, concludes that the remedy was of much advantage, though not wholly curative by itself (British Medical Journal, ii., 1877); and it seems to me that in this case more allowance should be made for the change of air and diet, the girl having come from Wales to London.
In a case of Dr. Whipham's, whatever good was obtained in the first month of treatment was lost in the second, and in several cases within my own knowledge - severe and chronic cases, it is true - phosphorus was given without benefit. It would seem, then, that it is uncertain as a remedy, and, without denying its occasional power of relieving, I think, with Erasmus Wilson, that it is indicated rather for the impaired nerve-condition accompanying many skin disorders than for any direct influence upon the nutrition of the skin.
Arsenic is largely used by the profession, almost as a routine remedy, in cutaneous disease, but its value has been variously estimated by specialists of experience. We may exclude at once from its influence the ordinary acute exanthemata, also naevus, parasitic and syphilitic eruptions, and the rarer maladies of scleroderma, keloid, xanthelasma, and true leprosy. We may exclude also all forms of skin disease while in the acute stage, or while accompanied by marked inflammatory reaction, and then, speaking generally, we may say that as we have noted arsenic to be valuable in rheumatic, malarial, and neurotic affections, so is it also valuable in most cutaneous manifestations of these conditions. With regard to the last-mentioned, my own experience agrees rather with that of Hunt and of Anstie, as against Bazin and others, that in neurotic subjects with highly strung excitable natures, arsenic is less readily borne, and more usually causes diarrhoea.
The forms of skin disease in which the remedy is of generally accepted value, are such as psoriasis, eczema in the dry or scaling stage, pemphigus, lichen, alopecia, and chronic urticaria; and those in which its powers are more controverted are acne, lupus, ichthyosis, herpes zoster,1 sycosis, prurigo, epithelioma, cancer, and elephantiasis graecorum.