Usnea Lichen: A Wild Antibiotic


Usnea Lichen: A Wild Antibiotic

Have you ever noticed those green, brown and sometimes yellow threads hanging off the branches of trees? Have you ever wondered if they are harming the tree and what they are doing there? Those strange creatures are actually lichens, which live on the outer surface of the tree and don’t cause any harm at all.

Lichen is a complex organism formed by the union of fungus and algae. Both organisms are able to live independently but they have found a way to live together to the benefit of both. The fungus provides a home and mineral nutrients to the algae and the algae provides sugar produced via photosynthesis to the fungus.

The hair-like lichen you see growing off of trees are all commonly referred to as old man’s beard. However, this common name actually refers to quite a few different species. The most common species used medicinally belong to the genus Usnea. Usnea lichens are green-grey and often have many smaller branches giving them a “bottle-brush” appearance. A key identification tool is to pull one of the threads apart to find a white “elastic” cord in the middle. It is important to take care in making the correct identification as I have frequently seen the bright yellow, poisonous wolf lichen (Letharia vulpina) growing beside Usnea in white spruce stands. Usnea should also only be harvested from clean ecosystems because slow- growing lichens concentrate environmental pollutants such as heavy metals.

Usnea has a long tradition of use in Europe as well as China, where it was used topically for wounds and internally for acute respiratory and digestive problems. In recent years research has focused on usnic acid, a chemical constituent of Usnea that has been shown to have strong antibiotic properties. In some cases it was even shown to be a stronger antibiotic than penicillin. This has led to a lot of interest in the use of Usnea to treat acute infections such us coughs and colds, as well as urinary tract infections.

Usnic acid is not soluble in water and so alcohol and oil extracts are considered the most effective. However, in China Usnea was traditionally made into a decoction (boiled tea). Research into the water-soluble polysaccharides (complex sugars) has found they can modulate the immune system, much like medicinal mushrooms, with the potential to enhance immune function. Although we have a fondness for identifying the single active constituent, the complex chemical mixture of lichens and plants often has many important parts that work together.

Despite a few concerns for safety, Usnea really is a safe and wonderful herb to keep in the medicine cabinet. I would highly recommend using it for productive coughs and urinary tract infections. It is really nourishing to the mucous membranes that line these areas. You can also apply Usnea directly as a bandage if you injure yourself in the forest, the antibacterial properties will help to keep your wound clean.

Usnea lichens help to keep the air around trees, the lungs of the earth, clean. So take care when harvesting it to not take too much. Be mindful that it is slow growing, and that for medicinal purposes you really only need a small amount. When you take it home think about the fact that it remains a fully living being and can survive in your home for many years. When you process your lichen treat it with respect. It’s a bit like throwing a living crab into boiling water.

Usnea Tincture Recipe

There are quite a few different recipes that discuss the best way to extract the chemical compounds of Usnea in a tincture. For home use I like to keep things simple, you can always get more complicated later on.

1) Grind or cut up the Usnea you have correctly identified and collected.

2) Put the Usnea pieces into a jar, compressing them to fit as much as you can.

3) Cover the Usnea with spirits of choice e.g. vodka, rum, brandy or gin. Make sure there is a good centimetre of alcohol above the lichen.

4) Allow Usnea to steep for 3-4 weeks. Put the jar where you can see it so you remember to shake it regularly.

5) Strain the herbs from the alcohol using a cheesecloth or mesh strainer followed by a coffee filter to remove all debris.

6) Store your tincture in a glass jar or bottle out of direct sunlight.


Take 1 mL (a little less than ¼ teaspoon or 1 dropper full) diluted in water 3 times daily to treat acute infections.


Some people are sensitive to the acid content of Usnea, which causes a burning sensation, so it is best to try a small amount before using it as a medicine. Also, because it is so potent it is safer to use for short periods of time in acute illness rather than long term. Women who are pregnant should not use Usnea.

Meet the Author, Latifa Pelletier-Ahmed

Latifa is a medical herbalist who has recently returned back to Calgary. Read more.

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