Botanical name

Cetraria islandica (L.) Acharius s. l.

Family

Lichens, Parmeliaceae

Common name

True Iceland lichen

Information about the plant

Botanically, Iceland moss is not a “moss”, but a lichen. Lichens represent a morphological unit of fungi and algae that live together in a symbiotic relationship. The fungus forms the hyphae that adhere to the soil, which the lichen uses to absorb water and nutrient salts, while the algae is responsible for photosynthesis, which plants use to build up their energy-rich compounds. The energy comes from sunlight. Both functions are important prerequisites for the survival of a plant. Lichens are particularly abundant in cool, humid places, but can also withstand drought, extreme heat, and extremely low temperatures for extended periods of time.

Iceland moss is widespread in the boreal, alpine, and arctic regions of the Northern Hemisphere, including Iceland. In the southern regions, it is primarily found in mountainous areas. The genus name Cetraria is probably derived from the Latin 'caetra' or 'cetra' (= shield, namely a light leather shield), which was intended to reflect the leathery, shield-like appearance of Iceland moss.

Iceland moss belongs to the shrub lichens because it forms an upright, up to 12 cm high, growing lichen body (= thallus). This antler-like body consists of toothed, grooved, and often rolled lobes. They are bristle-like ciliated, blue green on the upper side, and whitish gray with white spots on the underside. In high mountainous regions, brown-pigmented forms are also found, as the plant accumulates certain pigments to protect itself from the sun. The suffix “s.l.” (sensu latiore = in the broader sense) after the botanical name of the plant indicates that it is a diverse collective species.

Medicinally used parts of plants (herbal drug)

The whole or crushed thallus (Lichen islandicus - Iceland moss/Iceland lichen) is used.

The commercially available drug comes from wild collections, mainly in the Scandinavian regions, the Balkans, and Russia.

Constituents of the herbal drug

Iceland moss contains mucilage and bitter-tasting lichen acids.

Quality of the drug

The quality of Iceland moss/Iceland lichen (Lichen islandicus) is specified in the European Pharmacopoeia (Ph. Eur.).

Medical applications

Recognised medical use

The HMPC has classified Iceland moss as a traditional herbal medicinal product (see “Traditional use”).

ESCOP: For dry coughs and inflammation of the mucous membranes of the mouth and throat.

Traditional use

The HMPC has classified Iceland moss as a traditional herbal medicinal product (Article 16a of Directive 2001/83/EC). Based upon long-standing use, Iceland moss can be used to treat irritation of the mucous membranes in the mouth and throat, and an associated dry, irritating cough; it can also be used to treat temporary loss of appetite.

Herbal drug preparations in finished dosage forms

• Cut Iceland moss for tea preparation
• Aqueous thick extracts in juice
• Alcoholic-aqueous extracts in liquid preparations

Dosage

Finished medicinal product: see patient information leaflet.

Tea: drink a cup of Iceland moss tea several times a day. Daily dose: 4 to 6 g drug.

Preparation of a tea

Pour 150 mL of boiling water over 2 to 4 g of finely chopped Iceland moss and strain after 10 minutes. To reduce bitterness, the first infusion can be immediately poured off and replaced with 150 mL of boiling water.

Notes

There are no safety studies available on the use of Iceland moss during pregnancy and lactation. It is not recommended to use Iceland moss for coughs in children under 6 years of age, as these symptoms should be treated by a doctor.

Side effects

None known.

Interactions

None known.

References

Herbal drug monographs

HMPC (2015, 2022), ESCOP (2003), WHO Vol. 4

Further literature

Commentary on the European Pharmacopoeia (Iceland moss/Iceland lichen, No. 1439)