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.
In acne it should be the exception to prescribe arsenic. Mr. E. Wilson goes so far as to say that "no one having even a rudimentary acquaintance with cutaneous pathology and therapeutics would think of doing so," and yet I have certainly seen cases cured by this remedy after others had failed. According to Dr. Bulkley, this has occurred with all forms of acne - the simple, the indurated, and the rosaceous - and his best results have been attained with De Valangin's solution of chloride. Dr. Duhring speaks well of it in the indolent papular form, and many special authorities might be quoted to the same effect. This does not seem to me so unreasonable as it does to Mr. Wilson, for acne is frequently connected with gastric and uterine irritation, and we have seen that arsenic has great power to relieve various forms of this malady.
In "bromic acne" - the pustular rash which frequently follows the use of full doses of any bromide - arsenic is decidedly useful. If given concurrently with the bromide it will often prevent any skin trouble (Bartho-low; also Gowers, Lancet, i., 1878), and I can corroborate this observation.