This section is from the book "Botanic Drugs Their Materia Medica, Pharmacology and Therapeutics", by Thomas S. Blair. Also available from Amazon: Botanic Drugs, Their Materia Medica, Pharmacology and Therapeutics.
Pleurisy Root, Asclepias tuberosa. Not official now. (U. S. P. 1890.) It is listed in the National Formulary. Complex in composition, but containing no very active proximate. The more uniform action of the drug is inducing diaphoresis. Its expectorant properties are not well marked, though of sufficient intensity to make the drug of value for administration to children. Though a minor agent, the fact that it is carminative and does not disturb digestion makes it fill a really useful place. Asclepias has no direct influence upon pleurisy.
Dryness of the respiratory mucous membranes, especially when associated with a dry skin and slight fever, is a condition met in many respiratory troubles. Asclepias may be depended upon to aid more direct medication, its diaphoretic action making of it a valuable cooperating agent. It does not have any direct influence upon febrile processes; but a combination of aconite and asclepias is often much more effective than is aconite alone. Its indications are such that it finds a place in certain cases through the whole range of respiratory affections.
Don't depend upon asclepias alone to be anything but a good diaphoretic. Adults should take 1-drachm doses fl. in hot water until the skin becomes moist, and then reduce the dose. A little aconite and ipecac added to asclepias is better than a Dover's powder. Children need 5- to 10-minim doses fl., and physicians will find it a most admirable minor agent of distinct usefulness in diseases of children.
Asclepias Incarnata is a similar agent, but is emetic in large doses. The Asclepiadeae, more especially those of tropical origin, partake much of the properties of ipecac, and some species are anthelmintic. A thorough investigation of these plants might yield much valuable data.