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.
For upwards of twenty years I have been accustomed to use phosphorus in this affection, and can speak favorably of its power. I have notes of fifty-six cases wherein the pain quickly subsided under this treatment, and did not, so far as I know, subsequently return. In some instances phosphorus succeeded where arsenic had quite failed. The dose was 1/100 to 1/50 gr. three times daily.
With regard to the dose of phosphorus in neuralgia and nerve-disorders generally, I may say that in my experience the comparatively large doses recommended by Dr. A. Thompson cannot be tolerated for any length of time by the system. They may seem at first to stimulate, or rather over-stimulate, the nerve-centres, but after a short time they depress in a disastrous manner; while the small doses of 1/200 to 1/50 gr., continued for due time, nourish and strengthen nerve-tissue, without any evidence of undue excitement. A therapeutical, and not a physiological action, is to be always desired.