This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
Notwithstanding the vast consumption of hops in malt liquors, their effects on the system, and mode of operation, have not yet been thoroughly investigated, or satisfactorily determined. That they are tonic to the digestive function is generally admitted, and might be inferred from their intense bitterness. Almost universal experience would seem to have determined that they have the additional property of inducing heaviness, drowsiness, and even sleep; and by most they are believed to have that also, in some degree, of relieving pain. Nevertheless, Magendie was disposed to reject their claim to be considered narcotic, having given lupulin to the lower animals without any such effect; and others are not wanting who maintain the same opinion. Dr. Maton, however, found them to allay pain, produce sleep, and lower the pulse in twenty-four hours from 96 to 60 in the minute. (Pereira, Mat. Med., 3d ed., p. 1247.) Dr. William Byrd Page, of this city, in February, 1849, stated to the College of Physicians of Philadelphia, that he had found lupulin to possess extraordinary powers in allaying irritation of the genital organs, and had been in the habit of using it for that purpose for two years. The same fact has since been confirmed, on the continent of Europe, by Zambaco, who was induced to make experiments with it by an observation of Debout, in relation to its favourable influence in relieving painful erections. He gave from one to sixteen scruples, without producing disturbance of the nervous system, but with decided effects, of the nature referred to, on the genital organs. (See Lond. Med.
Times and Gaz., Feb. 1855, p. 118.) With their tonic, soporific, and anodyne properties, hops may, therefore, be considered antaphrodisiac. That they possess the power of stimulating the cerebral functions is extremely doubtful; and I am not, therefore, disposed to class them in the same category with opium and alcohol. From the large quantities taken with impunity, it is probable that their influence over the brain is feeble, and. from the symptoms evinced, that it is rather sedative than stimulant. In this uncertainty as to the precise position they ought to occupy, in reference to their influence over the nervous system, 1 have thought it best to rank them with the division of bitter tonics having peculiar properties, to which they undoubtedly belong, whatever claim they may have to a position elsewhere.
Opinion is not more settled as to the special influence of the several active principles of hops. It has been a prevalent impression that the odorous and volatile principle is that to which they owe their narcotic properties. The effect of a pillow of hops in producing sleep may be said to be almost notorious; and it is asserted that stupor has sometimes occurred in persons who have remained long in warehouses containing hops; but, in the former case, much allowance must be made for the operation of the patient's imagination; and, in the latter, it might be suggested that the experience of such an effect, if real, should be more than occasional, and that there might have been some other cause for the stupor when observed. Besides, Dr. Wagner states that he gave twenty drops of the volatile oil to a rabbit without observable effect. (Chem. Gaz., July 15, 1853.) In reference to the bitter principle, there is little more certainty, except as to its tonic action on the digestive organs. Dr. Christison is disposed to think, that whatever soporific virtues may be possessed by hops reside in the volatile oil, and consequently that the bitter principle is destitute entirely of narcotic properties. (Dispensatory.) Mr. Walter Jauncey, as the result of his experiments, found the oil to relieve pain, without necessarily producing sleep, and, in large doses, to reduce the frequency of the pulse considerably, and induce headache, anorexia, and nausea; and it acts in this way whether taken into the stomach, or inhaled. He also found it to act as a diuretic, and to allay the venereal appetite. His general conclusion was, that the oil is sedative and anodyne, and that humulin, or the bitter principle, is merely tonic. (Ed. Med. Journ., Feb. 1858, p. 701 ) Like all other bitters, hops are offensive to the stomach in over-doses.