This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol2", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
This is the root of Leontodon Taraxacum (Taraxacum Dens-leonis, De Cand.), or common dandelion, a small herbaceous plant, growing in almost all parts of the globe, and everywhere well known for its bright-yellow flowers, which are the ornament of every grass-plat in early spring. The peculiar shape of its leaf, irregularly incised at the edges, with the divisions pointing backward, has, from its fancied resemblance to that of the tooth of the lion, given origin to its name in several languages; as leontodon from the Greek, dens-leonis in the Latin, Lowenzahn in German, and dent de lion in French, which has been corrupted into our own name of dandelion. All parts of the plant exude, when wounded, an opaque, milky, bitterish liquid, with which its virtues are probably connected; as it is deemed efficacious in proportion to the amount of this juice contained in it. The root, however, which is much the strongest part, is the only one officinally recognized. This should be collected in the latter part of the summer, when it most abounds in the milky juice referred to. Though it retains its virtues when carefully dried, it deteriorates by time, and should, therefore, be collected every year; or, what is better, the officinal preparation should be made from the fresh root annually, at its period of greatest activity.
Dandelion root, when in perfection, is tapering, several inches long, about as thick as the finger where thickest, generally branching, of a light-brown colour externally, whitish within, inodorous, and of a sweetish, bitterish, and peculiar taste. Water and alcohol extract its virtues. A bitter, somewhat acrid, crystallizable principle called taraxacin has been obtained from it; but how far the virtues of the plant depend upon it has not been determined.
Dandelion has the reputation of being tonic, diuretic, and laxative, with alterative properties, and a special influence on the liver; but very gentle in all its physiological and therapeutic relations. I am not disposed to deny its possession of any of the powers ascribed to it; but it is so often given with other more active remedies, and of itself is so deficient in energy, that it is extremely difficult to decide how much of the favourable result, in any case, should be ascribed to it. Of its moderate tonic influence on the digestive function there is, I believe, no doubt. it is equally certain that it occasionally acts upon the bowels, though not to be relied on as a laxative. its diuretic property has been doubted; but the vulgar name by which it is known in this country, and the no less expressive ordinary designation of the plant in France, are sufficient evidence of the common belief on this point; and, upon a question so purely one of personal observation, I do not think that the general opinion can be mistaken. The chief reputation, however, of dandelion as a therapeutic agent, depends upon its supposed alterative influence, especially on the liver. To this point, there will be occasion to recur when the remedy is considered among the cholagogues. At present it is to be regarded merely as a diuretic. in this capacity, it is frequently used as an adjuvant of other medicines of the class, and particularly in the treatment of those forms of dropsy which are dependent on, or connected with hepatic disorder, whether functional or organic. These are usually abdominal; and it is probably in ascites, with organic disease of the liver, that dandelion is most employed as a diuretic. it may, however, be used in any ordinary case of dropsy, with a tendency to constipation, and deficiency of bile; and, in conjunction with other mild diuretics, in the form of infusion or decoction, as in the London compound decoction of broom, it may be given as an ordinary diuretic drink, without reference to special indications. it should not be used when the stomach and bowels are in an irritated state. The most common forms of administration are those of infusion or decoction and extract.
Infusion of Dandelion (infusum Taraxaci, U. S.) is made by macerating two troyounces of the bruised root, for two hours, in a pint of boiling water. The recently dried root should be preferred. The British Pharmacopoeia recommends the decoction, which is prepared by boiling an ounce of the root in one and a half pints (imperial measure) of water to a pint. But the virtues of taraxacum are impaired by heat and exposure; and the former mode of preparation is, I think, preferable. The dose of the infusion is a winglassful, twice or three times daily, or more frequently if requisite; that of the British decoction from two to four fluidounces, as often.
The Extract of Dandelion (Extractum Taraxaci, U. S., Br.) is the most convenient form for administration, and, if properly prepared, at the proper season, and kept duly excluded from the air in a cool place, is probably the best representative of the fresh root that we can obtain. it should be prepared from the root in August or September, after it has fully ripened, and before it has become injured by the frost, which converts its bitterness into sweetness. The juice, having been expressed, should be inspissated either in vacuo, or by means of a current of warm dry air, directed over the surface, in shallow vessels. The extract, however, is liable to deterioration by time, and should be prepared annually. The dose is from a scruple to a drachm, twice or three times daily. it is most conveniently administered, mixed with water, flavoured or not as may be desired, in such proportion that the dose may be contained in from half a fluidounce to a fluidounce of the menstruum.
The Fluid Extract (Extractum Taraxaci Fluidum, U. S ), of the U. S. Pharmacopoeia, is a very concentrated tincture, which may be given in the dose of one or two fluidrachms, three times a day.
The British Pharmacopoeia has a Juice of Taraxacum (Succus Taraxaci, Br.), made by expressing the fresh root, and adding rectified spirit to the juice, in the proportion of one measure of the former to three of the latter. The mixture is to be set aside for seven days, then filtered, and kept in a cool place. The dose is from two to four fluidrachms.