Iceland moss has been used since ancient times as a cough remedy and has also been used in European folk medicine as a cancer treatment[254]. In present day herbalism it is highly prized for its strongly antibiotic and demulcent actions, being used especially to soothe the mucous membranes of the chest, to counter catarrh and calm dry and paroxysmal coughs - it is particularly helpful as a treatment for elderly people[254]. Iceland moss has both a demulcent and a bitter tonic effect within the gut - a combination almost unique amongst medicinal herbs[254]. The whole plant is strongly antibiotic, antiemetic, strongly demulcent, galactogogue, nutritive and tonic[4, 7, 9, 21, 46, 61, 165, 238, 254]. It is excellent when used internally in the treatment of chronic pulmonary problems, catarrh, dysentery, chronic digestive disturbances (including irritable bowel syndrome and food poisoning) and advanced tuberculosis[4, 254]. Externally, it is used in the treatment of boils, vaginal discharges and impetigo[238]. The plant can be harvested as required throughout the year[7], preferably during dry weather, and can also be dried for later use[9]. Use with caution[21]. The German Commission E Monographs, a therapeutic guide to herbal medicine, approve Cetraria islandica for cough & bronchitis, dyspepsia, inflammation of mouth and pharynx, loss of appetite (see [302] for critics of commission E).