Usnea (Usnea barbata) is a lichen that grows on trees. Lichens appear to be a single plant, but they are really fungus and algae that grow together.

Usnea contains chemicals that are thought to fight germs that might cause infections. These chemicals might also decrease swelling, pain, and fever.

People use usnea for cough, obesity, pain, wound healing, and many other purposes, but there is no good scientific evidence to support these uses.

Don't confuse usnea with another lichen called oak moss. These are not the same.
When taken by mouth: Usnea is possibly unsafe. Usnea contains a chemical called usnic acid (sodium usniate) that might cause liver damage.

When applied to the skin: Usnea is possibly safe. But it might cause allergic reactions, including skin rash, in some people.

Special Precautions & Warnings:

Pregnancy and breast-feeding: There isn't enough reliable information to know if usnea is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Liver disease: Usnea contains some chemicals that might harm the liver. If you have liver disease, don't take usnea by mouth.


There is interest in using usnea for a number of purposes, but there isn't enough reliable information to say whether it might be helpful.
Likely effective Effectiveness definitions
Possibly effective Effectiveness definitions
Likely ineffective Effectiveness definitions
Possibly ineffective Effectiveness definitions
Insufficient evidence Effectiveness definitions

Dosing & administration

There isn't enough reliable information to know what an appropriate dose of usnea might be. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult a healthcare professional before using.

Interactions with pharmaceuticals

It is not known if Usnea interacts with any medicines. Before taking Usnea, talk with your healthcare professional if you take any medications.

Interactions with herbs & supplements

There are no known interactions with herbs and supplements.

Interactions with foods

There are no known interactions with foods. has licensed monographs from TRC Healthcare.
This monograph was last reviewed on 21/02/2022 00:29:17 and last updated on 26/09/2022 03:10:35. Monographs are reviewed and/or updated multiple times per month and at least once per year.
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