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.
This has been discarded both in the U. S. and British Pharmacopoeias, and is no longer officinal. It is the herb of Origanum vulgare or common marjoram, a perennial, herbaceous plant, growing wild both in Europe and the United States, and in this country found especially by the roadsides, from Pennsylvania to Virginia. It bears a rather conspicuous summit of pinkish-purple, or rose-coloured flowers, which appear during summer and early part of autumn. The herb has an agreeable aromatic odour, and a warm pungent taste. For these properties it depends on a volatile oil, which is separated by distillation, and for which alone the plant was recognized as officinal. The oil as first prepared is yellow, but becomes reddish by age, and is said to acquire the same colour when over-heated in distillation; but it may be obtained colourless by rectification. It is lighter than water, has the odour of the plant, and a hot acrid taste.
Origanum is a stimulating aromatic, and will answer the same purposes as the mints; but, being less agreeable to the taste, and probably less cordial in its influence on the stomach, is little used. Like pennyroyal and horsemint, it has been supposed to be diaphoretic and emmena-gogue; but, like them, probably acts in this way simply as a general stimulant, and when aided with suitable accompaniments, such as hot water in the form of infusion, and hot pediluvia. The oil is a powerful local irritant, and is sometimes employed as such externally, either alone or in connection with other medicines. Diluted with olive oil, it is used as a liniment in baldness, rheumatism, sprains, bruises, and paralytic affections. Occasionally it is employed to relieve toothache, being introduced on lint or cotton into the carious hollow It was an ingredient in the discarded Camphorated Soap Liniment of former editions of our Pharmacopoeia, so much employed, under the common name of opodeldoc, as an anodyne and gently rubefacient application.
Sweet Marjoram (Origanum Majorana) has been used, in powder, as an errhine, but has lost its place in the officinal lists, and is now seldom employed except as a spice in cooking.