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.
Cases described under these names, and which seem to be frequently of neuralgic type, are often quickly relieved by suitable doses of prussic acid. Pereira gives instances of very severe spasmodic pain, where there was no complaint of pyrexia, of faintness, nor of any ordinary symptoms of dyspepsia; the pain was such as to lead to suspicion of organic disease, but it disappeared under the use of the acid. In one case it was seated in the intestine, came on about 2 p.m., and lasted until night, unrelieved by many remedies until this one was used, and Pereira made the further observation that its action is exerted quickly, and either produces complete relief or none at all. Sir T. Watson "has seen more rapid and decided relief from it in gastrodynia than from anything else."