# Iceland moss (Cetraria islandica) *Iceland lichen, cetraria; Valerius Cordus’s *Muscus crispae Lacticae similis*; *Lichen islandicus* of Bartholin; *Cetraria islandica* (L.) Ach.; in pharmacy *Lichen islandicus** **Known today as.** *Cetraria islandica*, which, Grieve writes, “In spite of its name is not a Moss but a lichen,” common in northern countries and on mountains further south, in Britain on barren stony ground and abundant in the Grampians and the Welsh hills. Its thallus varies in size, division, and colour and is sometimes much curled; Grieve gives it about 70 per cent of lichen starch, which turns blue with iodine. The European Medicines Agency’s assessment report finds 25 to 50 per cent of polysaccharides, lichenan and isolichenan among them, and the bitter lichen acids fumaroprotocetraric and protolichesterinic acid. Kind: Fungus (lichen) > **Caution.** The European agency advises seeing a doctor if breathlessness, fever, or purulent sputum occurs. For the throat it does not recommend the tea under twelve or the lozenges under six, and for loss of appetite not under eighteen, for lack of data. Because the lichen absorbs heavy metals and radioactive fallout, the assessment report notes, the quality of the raw material matters. ## What was it used for? A soothing food-medicine for the chest and the gut. Grieve calls it “Demulcent, tonic, and nutritive when deprived of its bitter principle,” excellent in chronic chest troubles, catarrh, digestive disturbances, and dysentery, and says it could be ground and mixed with chocolate or cocoa. The assessment report records that Linnaeus (1737) thought it an important medicine, emollient and tonic, in chronic affections, and that in 1838 Lindley found it popular in Europe for consumption, chronic catarrh, dyspepsia, and chronic dysentery. ## What does modern science say? The European Medicines Agency’s herbal committee accepts the lichen as a traditional herbal medicine, “exclusively based upon long-standing use,” as a demulcent for the symptomatic treatment of irritation of the mouth or throat and the dry cough that goes with it, and for temporary loss of appetite (monograph of 2014). Lozenges of its water extract are widely used; the report cites clinical studies in 163 patients and a post-marketing study in 3,143 children showing good tolerance. ## Pharmacognosy and toxicology - **lichenan**: with isolichenan among the polysaccharides, 25 to 50 per cent - **isolichenan**: - **fumaroprotocetraric**: one of the bitter lichen acids, with protolichesterinic acid - **protolichesterinic acid**: **Mechanism.** Not established in the sources read for this entry. **Standing.** European Union herbal monograph (2014): traditional use, “exclusively based upon long-standing use,” as a demulcent for mouth and throat irritation with dry cough, and for temporary loss of appetite. ## What lore surrounds it? In arctic and subarctic lands, the assessment report records, lichens including this one were emergency food in famine, and in ordinary years made bread and dessert jellies, first treated with alkaline wood ash and boiling water to remove the bitter lichen acids. The precaution mattered: untreated Iceland moss at half the diet killed mice in four or five days, while ash-soaked and boiled lichen at a quarter of it left them in good condition after six weeks. The lichen also gathers heavy metals and radioactivity from the air; after Chernobyl it was hard to find Scandinavian material below 600 becquerels. ## What did the older authorities say? **The European Medicines Agency’s assessment report (2014), after Madaus.** The medieval botanist Valerius Cordus first mentioned it as “Muscus crispae Lacticae similis”; Breyne drew it in 1672, and in the same year Bartholin first described it as *Lichen islandicus*, considering it a spring purgative. Hjärne undertook its first chemical research in 1744. It has stood in the Austrian, Swiss, German, Czechoslovak, British herbal, and European pharmacopoeias through the twentieth century. ## Sources - Grieve, M. *A Modern Herbal*, “Moss, Iceland.” As published on botanical.com. - European Medicines Agency, Committee on Herbal Medicinal Products. *European Union herbal monograph on Lichen islandicus (Iceland moss)*. EMA/HMPC/678891/2013, 24 November 2014. - European Medicines Agency, Committee on Herbal Medicinal Products. *Assessment report on Lichen islandicus*. EMA/HMPC/36866/2014, 24 November 2014. - European Medicines Agency, Committee on Herbal Medicinal Products. *European Union herbal monograph on Lichen islandicus (Iceland moss)*. EMA/HMPC/678891/2013, 24 November 2014. - European Medicines Agency, Committee on Herbal Medicinal Products. *Assessment report on Lichen islandicus*. EMA/HMPC/36866/2014, 24 November 2014. - Grieve, M. *A Modern Herbal*, “Moss, Iceland.” As published on botanical.com. --- *Iceland moss.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-16. The Thinking Press. https://thethinkingpress.org/materia-medica/iceland-moss Historical description, not medical advice.