FWD 2 Expanded Commission E: Iceland moss

Herbal Medicine: Expanded Commission E

Iceland moss

Latin Name: Cetraria islandica
Pharmacopeial Name: Lichen islandicus
Other Names: fucus, muscus


Iceland moss is a lichen harvested and prepared in Scandinavia and Europe as a medicinal agent to stimulate the appetite and relieve dry cough and inflamed oral tissues (Schulz et al., 1998; Tyler, 1994). The therapeutic actions of Iceland moss are attributed to its mucilaginous polysaccharides (Tyler, 1994). Contemporary and traditional use of Iceland moss for the relief of upper respiratory catarrh is supported by results from recent clinical studies. In a randomized trial, Iceland moss was found to prevent both dryness and inflammation of the oral cavity in patients who had undergone surgery of the nasal septum and were subjected to prolonged mouth breathing following surgery. Emollient effects were noticeable with the daily use of 0.48 mg Iceland moss lozenges (Kempe et al., 1997).

Iceland moss polysaccharides have been the focus of a number of experimental studies. One in particular, protolicheresterinic acid, may prove to be valuable in the treatment of ulcers and cancers, and in AIDS prevention. In vitro activity against Helicobacter pylori (Ingolfsdottir et al., 1997) and DNA polymerase activity of human immunodeficiency virus-1 reverse transcriptase (Pengsuparp et al., 1995) have been documented. Protolicheresterinic acid is also antiproliferative and cytotoxic to T-47D and ZR-75-1 cell lines cultured from breast carcinomas, and to K-562 from erythro-leukemia. Significant inhibition of 5-lipoxygenase may stimulate these activities and contribute to protolichesterinic acid's reported anti-inflammatory actions (Ogmundsdottir et al., 1998).

Historically, Iceland moss has provided both medicine and food for the people of Iceland, Norway, Finland, Russia, and Sweden. It has been made into flour for bread (Schneider, 1904), and gelled and mixed with lemon, sugar, chocolate, or almonds to make confections (Dannfelt, 1917). During the 18071814 famine in Norway, it was used as food (Richardson, 1988). During World War II, Iceland moss was prepared into a type of molasses in Russia (Llano, 1956). Always, powdered material must be soaked in lye for 24 hours or filtered through ash in order to properly extricate lichen acids. Studies demonstrate that poorly prepared Iceland moss contains probably toxic levels of lead (Airaksinen et al., 1986).

Medicinal uses include as a tonic during convalescence, gastrointestinal demulcent, and treatment for upper respiratory catarrh (Lindley, 1849). Iceland moss decoctions, infusions, and gargles have been used to treat colds, whooping cough, asthma, diabetes, and nephritis (Ahmadjian and Nilsson, 1963), and for post-tuberulosis convalescence (Lokar and Poldini, 1988). Cough drops for sore throats and laxative and tonic formulations are available in European pharmacies (Richardson, 1991).


Iceland moss consists of the dried thallus of Cetraria islandica (L.) Acharius s.l. [Fam. Parmeliaceae] and its preparations in effective dosage. The herb contains mucilage and bitter principles.

Chemistry and Pharmacology

Constituents include about 50% water-soluble polysaccharides, including lichenin, a linear cellulose-like polymer of b-D-glucose, and isolichenin, a linear starch-like polymer of a-D-glucose (Wichtl and Bisset, 1994). Iceland moss also contains galactomannans and an acidic, branched polysaccharide containing D-glucose and D-glucuronic acid units. Other constituents include bitter-tasting lichen acids, including the depsidones fumarprotocetraric acid and protocetraric acid, and the aliphatic lactone protolichesterinic acid (ESCOP, 1997).

The Commission E reported soothing and mildly antimicrobial acitivities. The polysaccharides are thought to form a soothing, protective, mucilaginous layer on the mucosa of the upper respiratory tract. Significant immunostimulating activity was shown in an in vitro study on an alkali-soluble galactomannan isolated from Iceland moss (ESCOP, 1997).


The Commission E approved Iceland moss to treat irritation of the oral and pharyngeal mucous membranes and accompanying dry cough, and loss of appetite. In an open clinical trial, 100 patients with pharyngitis, laryngitis, or bronchial ailments were treated with lozenges containing 160 mg of an aqueous extract of Iceland moss. The results were determined to be positive in 86 cases with good gastric tolerance and lack of side effects (ESCOP, 1997).


Iceland moss is contraindicated in gastro-duodenal ulcers due to its mucosa-irritating properties (McGuffin et al., 1997).

Side Effects

None known.

Use During Pregnancy and Lactation

No restrictions known.

Interactions with Other Drugs

None known.

Dosage and Administration

Unless otherwise prescribed: 4-6 g per day of cut herb.

Infusion: 4-6 g of herb in 150 ml water.

Fluidextract 1:1 (g/ml): 4-6 ml.

Tincture 1:5 (g/ml): 20-30 ml.


Ahmadjian, V. and S. Nilsson. 1963. Swedish lichens. Yearbook (American Swedish Historical Foundation).

Airaksinen, M.M. et al. 1986. Toxicity of plant material used as emergency food during famines in Finland. J Ethnopharmacol 18(3):273296.

Dannfelt, H.J. 1917. Kungl Lantbrukssakad Tidskr 6:483498.

ESCOP. 1997. 'Lichen islandicus.' Monographs on the Medicinal Uses of Plant Drugs. Exeter, U.K.: European Scientific Cooperative on Phytotherapy.

Ingolfsdottir, K. et al. 1997. In vitro susceptibility of Helicobacter pylori to protolichesterinic acid from the lichen Cetraria islandica. Antimicrob AgentsChemother 41(1):215217.

Kempe, C., H. Gruning, N. Stasche, K. Hormann. 1997. [Icelandic moss lozenges in the prevention or treatment of oral mucosa irritation and dried out throat mucosa] [In German]. Laryngorhinootologie 76(3):186188.

Lindley, J. 1849. Medical and Economical Botany. London: Bradbury and Evans.

Llano, G.A. 1956. Utilization of lichens in the arctic and subarctic. Econ Bot 10(4):367392.

Lokar, L.C. and L. Poldini. 1988. Herbal remedies in the traditional medicine of the Venezia Giulia region (north east Italy). J Ethnopharmacol 22(3):231279.

McGuffin, M., C. Hobbs, R. Upton, A. Goldberg. 1997. American Herbal Product Association's Botanical Safety Handbook. Boca Raton: CRC Press.

Ogmundsdottir, H.M., G.M. Zoega, S.R. Gissurarson, K. Ingolfsdottir. 1998. Anti-proliferative effects of lichen-derived inhibitors of 5-lipoxygenase on malignant cell-lines and mitogen-stimulated lymphocytes. J Pharm Pharmacol 50(1):107115.

Pengsuparp, T. et al. 1995. Mechanistic evaluation of new plant-derived compounds that inhibit HIV-1 reverse transcriptase. J Nat Prod 58(7):10241031.

Richardson, D.H.S. 1988. Handbook of Lichenology, Vol. 3. Boca Raton: CRC Press.

. 1991. Frontiers in Mycology. Honorary and General Lectures from the Fourth International Mycological Congress, Rengensburg, Germany, 1990.

Schneider, A. 1904. A Guide to the Study of Lichens. Boston: Knight and Miller.

Schulz, V., R. Hnsel, V.E. Tyler. 1998. Rational Phytotherapy: A Physicians' Guide to Herbal Medicine. New York: Springer.

Tyler, V.E. 1994. Herbs of Choice: The Therapeutic Use of Phytomedicinals. New York: Pharmaceutical Products Press.

Wichtl, M. and N.G. Bisset (eds.). 1994. Herbal Drugs and Phytopharmaceuticals. Stuttgart: Medpharm Scientific Publishers.

Additional Resources

Braun, R. et al. 1997. Standardzulassungen f r FertigarzneimittelText and Kommentar. Stuttgart: Deutscher Apotheker Verlag.

British Herbal Pharmacopoeia (BHP).1983. Keighley, U.K.: British Herbal Medicine Association.

Deutsches Arzneibuch, 10th ed. Vol. 16. (DAB 10). 1991. Kommentar. (4 Lfg. 1994) Stuttgart: Wissenschaftliche Verlagsgesellschaft mbH. M84.

Ingolfsdottir, K., K. Jurcic, B. Fischer, H. Wagner. 1994. Immunologically active polysaccharide from Cetraria islandica. Planta Med 60(6):527531.

Ingolfsdottir, K., G.A. Chung, V.G. Skulason, S.R. Gissurarson, M. Vilhelmsdottir. 1998. Antimycobacterial activity of lichen metabolites in vitro. Eur J Pharm Sci 6(2):141144.

Kartnig, T. 1987. Cetraria islandicaIslandisches Moos. Z Phytother (8):127130.

Stecher, P.G. (ed.). 1968. The Merck Index: An Encyclopedia of Chemicals and Drugs, 8th ed. Rahway, N.J.: Merck & Co., Inc.

Vorberg, G. 1981. Flechtenwirkstoffe lindern Reizzustande der Atemwege. Neben den entzundungshemmenden Eigenschaften wirkt sich der Schleimhautschutz besonders gunstig aus. Arztl Praxis (33):3068.

Weiss, R.F. 1988. Herbal Medicine. Beaconsfield, England: Beaconsfield Publishers.

This material was adapted from The Complete German Commission E MonographsTherapeutic Guide to Herbal Medicines. M. Blumenthal, W.R. Busse, A. Goldberg, J. Gruenwald, T. Hall, C.W. Riggins, R.S. Rister (eds.) S. Klein and R.S. Rister (trans.). 1998. Austin: American Botanical Council; Boston: Integrative Medicine Communications.

1) The Overview section is new information.

2) Description, Chemistry and Pharmacology, Uses, Contraindications, Side Effects, Interactions with Other Drugs, and Dosage sections have been drawn from the original work. Additional information has been added in some or all of these sections, as noted with references.

3) The dosage for equivalent preparations (tea infusion, fluidextract, and tincture) have been provided based on the following example:

  • Unless otherwise prescribed: 2 g per day of [powdered, crushed, cut or whole] [plant part]
  • Infusion: 2 g in 150 ml of water
  • Fluidextract 1:1 (g/ml): 2 ml
  • Tincture 1:5 (g/ml): 10 ml

4) The References and Additional Resources sections are new sections. Additional Resources are not cited in the monograph but are included for research purposes.

This monograph, published by the Commission E in 1994, was modified based on new scientific research. It contains more extensive pharmacological and therapeutic information taken directly from the Commission E.

Excerpt from Herbal Medicine: Expanded Commission E Monographs
Copyright 2000 American Botanical Council
Published by Integrative Medicine Communications
Available from the American Botanical Council.