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.
Cinnamomum Cassia is Chinese Cinnamon, and from it Oil of Cassia is derived. Several species are known as Saigon cinnamon. The true Ceylon cinnamon, unquestionably the best cinnamon, is C. Zeylanicum. The U. S. P. does not sufficiently differentiate, the true oil (Ceylon) not even being official.
Kobert classes natural and artificial oil of cinnamon as one of the volatile oils having a strong antiseptic action. The oil is composed principally of cinnamic aldehyde. Cinnamon is carminative, stimulant and aromatic, and somewhat astringent. The oil has no astringent properties, but is reputed to be an emmenagogue, causing the uterus to contract. A ten per cent. spirit of the oil is official and is used in 5 - to 30-minim doses to check uterine hemorrhage. A tincture of Ceylon cinnamon is to be preferred. I doubt if small doses are effective in uterine hemorrhage, and larger doses are objected to by the patient.
In passive uterine hemorrhage and hematuria it has commonly failed in my hands. Perhaps if the oil were given in soluble elastic capsules, the patient would take sufficient dosage to secure an effective action. My patients would rarely tolerate over 5 minims of a 10 per cent. tincture, and these doses are not effective. True oil of Ceylon cinnamon is very expensive.
As a flavor, cinnamon spirit and cinnamon water serve admirably.