Educational information, not medical advice — ask your doctor or midwife.
Hooded tube lichen is a common grey-green lichen of northern forests. It grows in flat, ruffled patches on bark, twigs and old fences. In Norway and Sweden it is called blærelav or blåslav.
A lichen is not a plant. It is a fungus and an alga living together as one body. This one has hollow, puffed lobes that split at the tips.
In Scandinavia it was used mostly as a wool dye and as emergency animal fodder. Folk medical use was local and small.
There is no good human evidence that it treats any illness. Traditional use is not proof that a remedy works, and it is not proof that it is safe. Its best-known effect in people is an itchy skin rash in those who handle it a lot.
No one has shown how it works in people, because it has not been tested that way. What exists is laboratory work.
In test tubes, extracts slow the growth of some bacteria and some fungi. Physodic acid and atranorin are the compounds most often studied.
In cell studies, these acids appear to mop up free radicals (unstable molecules that damage cells). Some cell work also hints that they calm signals tied to swelling and redness.
Whether any of that happens on human skin, or inside the body, is not established. A lab dish is not a person.
There is a practical catch too. Lichen acids dissolve poorly in water. A simple water tea may carry very little of them.
The skin reaction is better understood. The same acids act as contact allergens. They can set off an itchy rash in people who become sensitive to them.
It is mainly sold and traded as a craft material, not as a medicine.
Dyers, foragers and craft sellers handle these forms:
- Dried whole lichen, sold in bags for wool and yarn dyeing. - Foraged fresh material, picked from fallen branches after storms. - Rare small-batch tinctures and salves from foragers and craft sellers.
Two more forms are used only by scientists:
- Research extracts made with alcohol or acetone, used in laboratories only. - Reference samples used to measure air pollution.
You will not find it in mainstream pharmacies or standard supplement ranges. There is no quality standard, no required testing and no set strength.
Perfume and cosmetic products that mention lichen usually contain oak moss (Evernia prunastri), a different species. If you react to one, you may react to the other.
Scandinavian country households valued it as a dye plant. Boiled with wool, it gave soft browns, yellows and rusty tones.
In hard winters, farmers in Norway and Sweden gathered bark lichens as fodder for sheep, goats and cattle. Reindeer eat it in the wild. People ate lichens only in famine years, and this one was never a preferred food.
Scattered folk records mention lichen washes and poultices laid on sores, cuts and skin complaints. Some northern European folk practice used bitter lichens for coughs. These records are thin and rarely name this species with any certainty.
It also has a long history as an unwanted irritant. Forestry workers and woodcutters in Europe developed an itchy rash known as woodcutter's eczema from handling bark lichens.
Stop using it and wash the skin with soap and water if a rash, itching or redness appears.
See a doctor if any of these happen:
- The rash spreads, blisters, weeps or does not settle within a few days. - The skin becomes hot, swollen or painful, which can mean infection. - The rash keeps coming back after further contact. - You swallowed the lichen and feel sick, have stomach pain or keep vomiting. - Your skin or the whites of your eyes turn yellow (jaundice), which can signal liver trouble.
Call emergency services at once for swelling of the lips, tongue or throat, a tight chest, wheezing or trouble breathing. These can mean a severe allergic reaction.
It is not an approved medicine in the EU, the UK, the USA or the Nordic countries. No health claim for it has been authorised.
It is not an authorised novel food in the EU or UK, so it cannot be sold legally as a food. Picking is usually allowed under Nordic right-of-access rules, but not inside nature reserves or national parks, where collecting lichens is restricted.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
One email with the summary. We'll also send a short weekly evidence update — unsubscribe any time.
