Botanical name: 

Synonyms.—Carrageen; Irish Moss.

Chondrus consists of the dried thallus of the seaweed, Chondrus crispus, Stackh. (N.O. Gigartinaceae), which is found on the northern shores of the Atlantic Ocean, but collected for medicinal purposes chiefly on the northern shores of Brittany, where it grows just below low-water mark upon rocks and stones. It is official in the U.S.P. When fresh it varies in colour from green to dark purplish-brown, but it is partly bleached by watering and exposing it to the sun. It is also said to be bleached artificially, by means of potassium permanganate. After bleaching it is dried, and then constitutes the so-called "Irish Moss" of commerce. The drug occurs in yellow, translucent, horny masses, which, when separated, are seen to consist of several of the slender thalli. These vary from 5 to 30 centimetres in length, are rounded at the base, but flattened in the upper part, and branch dichotomously, the ultimate branches having an emarginate or two-lobed apex. When softened in water the drug becomes gelatinous. On incineration it yields from 8 to 15 per cent. of ash.

Constituents.—The chief constituent of Irish moss is about 64 per cent. of a carbohydrate, called carrageenin. The drug also contains about 7 per cent. of proteins and a little iodine.

Action and Uses.—Irish moss is used as a food on the coasts of Ireland, where it abounds, and nutritious preparations, such as Irish moss jelly, are made for invalid use, but the carbohydrates are not very readily digestible. Decoction of Irish moss is a demulcent, and is occasionally given in coughs and for bladder irritation and catarrh. It is also employed as an emulsifying agent for cod-liver and other oils.


Decoctum Chondri, B.P.C.—DECOCTION OF IRISH MOSS. Syn.—Mucilago Chondri; Mucilage of Irish Moss. 1 in 40.
Demulcent and nutritive. Used in coughs, bronchitis, and in catarrh of the bladder, and in the preparation of emulsions. Dose.—30 to 120 mils (1 to 4 fluid ounces), or more.

The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.