What is Iceland moss?

Iceland moss is not a moss. It is a lichen, which is part fungus and part alga. It grows on cold, open ground across the far north.

People take it for a dry, tickly cough and a raw throat. It is also an old bitter tonic for poor appetite. The dried plant is full of slimy sugars called mucilage.

Here is the short evidence verdict. Good human trials are few, small and weak. Its standing rests on long use and on European traditional-use approval, not on strong proof.

Long use is not proof. It does not show that a remedy works, and it does not show that it is safe. That point applies to everything on this page.

How does Iceland moss work?

The main idea is simple and physical. Mucilage swells in water and forms a soft film. That film may coat a sore throat and ease the urge to cough.

This soothing effect has not been measured well in people. It is the same idea behind marshmallow root and slippery elm. Both are thought to work by coating, not by drug action.

Iceland moss also holds bitter lichen acids. In test tubes, some of these acids slow the growth of bacteria. Whether that happens in a human throat is not known.

Bitter herbs are said to wake up taste nerves and raise appetite. In people, this effect is mostly untested. Treat it as an old idea, not a proven one.

What forms does Iceland moss come in?

Iceland moss is sold mainly as throat products. Lozenges and pastilles are the most common form in Europe.

Other forms you may see: - Loose dried lichen for tea - Tea bags, often blended with other herbs - Cough syrups and mouth sprays - Liquid extracts and tinctures - Capsules, which are less common

The tea is thin and slightly bitter. A cold soak draws out more slime and less bitterness. Honey is often added to make it easier to drink.

Quality varies a lot. Choose a seller that tests for heavy metals. Avoid lichen gathered beside roads or near factories.

Where it comes from:

Iceland moss has a long record as a famine food and a cough remedy. Northern Europeans boiled it, washed out the bitterness, and mixed it with flour or milk.

American folk and Eclectic doctors of the 1800s took up the same uses. Their books listed it for dry coughs, wasting illness and poor appetite. It was often given as a thick boiled drink.

It later entered official European herbal medicine. German authorities and the European Medicines Agency both list it for mouth and throat irritation, dry cough and loss of appetite. That listing is based on tradition and safe long use, not on trial results.

What does Iceland moss help with?

• Dry, tickly cough: This is the main traditional use. The slime is thought to coat the throat and settle the tickle. European regulators allow this use based on tradition alone. That is not the same as trial proof. I found no strong human trials to support it. Any relief is likely short and mild, like a plain cough sweet.
• Sore or scratchy throat: Lozenges are the usual form for this. The coating idea is the same as for cough. The effect, if any, lasts only while the film is there. It does not treat the cause of the soreness. A sore throat with high fever or trouble swallowing needs a doctor, not a lozenge.
• Hoarseness and dry mouth: Singers and speakers have long used Iceland moss lozenges. The aim is to keep the throat moist. Human evidence here is thin and mostly comes from product makers. Plain water, steam and voice rest are the usual first steps.
• Poor appetite: Eclectic and European practice used it as a bitter. Bitters were given shortly before meals to spark hunger. This use sits on tradition. Controlled human studies in people with poor appetite are lacking. Lost appetite with weight loss is a warning sign. Get it checked rather than treating it yourself.
• Mild stomach upset: Folk use included soothing a sore or irritated gut. The slime was thought to line the stomach. There is no reliable human trial support for this. The bitter acids may also irritate some people instead.

Which foods are rich in Iceland moss?

Iceland moss is not found in everyday food. In hard times it was boiled, washed and baked into bread or porridge in Iceland and Scandinavia.

What are the side effects of Iceland moss?

• Nausea
• Stomach ache or heartburn
• Strong bitter taste
• Loose stools at high amounts
• Allergic rash or itching (rare)
• Liver strain, linked mainly to strong usnic acid products (rare)

Good to know:

Most people tolerate tea and lozenges well. Mild stomach upset is the usual complaint.

Serious harm is rare at food-style amounts. The real concern is concentrated extracts rich in usnic acid, which have been tied to liver injury.

Stop and seek advice if you feel sick, your skin or eyes turn yellow, or your stomach hurts.

How much Iceland moss should you take?

• Recommended daily: The amounts below are what labels and European monographs tend to carry. They are not advice for you. Tea labels often list about 1 to 2 g of dried lichen per cup. Daily totals on such labels usually sit near 4 to 6 g. Lozenge packs set their own limits, often a few per day. Follow the pack, and ask a pharmacist if you are unsure. Children's doses are lower, and some packs are not for young children at all.
• Best time of day: Timing does not matter much. For throat use, people take it when the throat feels raw, including at bedtime. As a bitter for appetite, tradition used it shortly before meals. Keep a gap of at least two hours from any other medicine you swallow. The slime can slow how a drug is taken up.
• With or without food: Either is fine for throat and cough use. As a bitter, it was taken before food on an empty stomach. If it makes you feel queasy, take it with food instead.
• Time to effect: If it helps, it helps fast. A coating effect is felt within minutes and fades as it washes away. That means it needs repeating through the day. It may also do nothing. Many people notice no change at all, and the evidence does not promise one.
• How long to take it: Traditional-use labels treat this as a short-term remedy. Most advise stopping and getting advice if a cough lasts more than a week. Long, nonstop use is not backed by evidence. Concentrated extracts are the bigger worry, because of usnic acid and the liver. If you want to use it for weeks, speak to a doctor or pharmacist first.