Iceland Moss

BotanicalLichen

What is it

Iceland moss (Cetraria islandica) is a lichen of cold northern climates, used traditionally as a demulcent for dry cough, throat irritation, and indigestion, and historically as a famine food in Iceland.

Evidence for 1 use

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Dry cough and throat irritation

Limited Evidence

Recognized in European herbal monographs; modern clinical evidence is limited but consistent with the soothing demulcent mechanism.

How it works

The lichen is rich in mucilage (lichenin and isolichenin), which forms a viscous protective layer over irritated mucous membranes. It also contains lichen acids (such as usnic acid) with antimicrobial activity in vitro. The traditional preparation is decoction (boiled lichen).

Dosage

Traditional dose is 4-6 g of cut lichen as decoction daily, divided into doses, or 1-2 mL of liquid extract two to three times daily.

When and how to take it

Tea taken as needed for cough or throat symptoms. Space from other oral medications to avoid mucilage interference.

2 commercial forms

Compare the main delivery options and what they’re best suited for.

Cut lichen / decoction

Most traditional and safest form.

Mucilage extracts well in water.

Tincture/fluid extract

Modern herbal preparation.

More concentrated; quality varies.

Safety

Generally well tolerated in traditional doses. Concentrated extracts that isolate usnic acid have caused liver injury; the whole lichen tea is far lower risk.

Who should be cautious

Avoid concentrated usnic acid extracts. Pregnancy/breastfeeding: data limited; prefer brief traditional uses if at all.

Interactions

Mucilage may reduce absorption of medications taken at the same time. Avoid concentrated usnic acid alongside hepatotoxic drugs.

Food sources

Iceland moss (historically used as famine food)

Amount
n/a
%DV
—

Frequently asked questions

Is Iceland moss a true moss?⌄

No, it is a lichen. The name is a historical misnomer.

Is Iceland moss safe?⌄

Traditional tea preparations are considered low risk. Avoid concentrated usnic acid extracts because of potential liver toxicity.

References

Iceland Moss on Wikidata — Wikidata link

Iceland Moss on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Iceland Moss (PubMed search) — PubMed link

Track Iceland Moss with Pilora

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.