Iceland moss
Cetraria islandica
Other names: Iceland lichen, Lichen islandicus
Edible plantPhoto credit: Franz Eugen Köhler / Wikimedia Commons
Safety information
Safety information
Toxicity: low - generally well tolerated; rare GI upset/nausea. Usnic acid is a known hepatotoxin at high/isolated doses, but at traditional thallus exposures liver injury is not characteristic.
Contraindications: pregnancy/breastfeeding (insufficient data - caution); known lichen allergy; peptic ulcer (bitter use).
Interactions: mucilage may delay/reduce absorption of co-administered oral drugs (separate dosing); limited other data.
Pregnancy & breastfeeding: caution in pregnancy/breastfeeding (insufficient data)
Evidence level
Documented in systematic traditional medicine literature.
Preparations
infusion · whole thallus
Part used: whole thallus
Traditional use: dry irritating cough, mouth/throat mucosa irritation, loss of appetite
Proposed mechanism: water-soluble mucilage (lichenin/isolichenin) demulcent
Associated conditions
Edibility
Edible parts: marginal - historically used as famine food (debittered/boiled to remove bitter lichen acids); not a routine food
Toxic lookalike warning
harvest only correctly identified lichen; some lichens contain high usnic acid / are unsuitable
Nutritional notes
polysaccharide mucilage (lichenin) - primarily demulcent rather than nutritive; minor
Healing traditions
Sources (3)
- EMA: Lichen islandicus (EMA/HMPC)
- EU herbal monograph on Cetraria islandica (EMA/HMPC)
- Iceland moss - Herbal Reality profile