Overview

Oak moss (Evernia prunastri) is a lichen that grows on oak trees. Lichens look like a single plant, but they are really fungus and algae that grow together.

Oak moss contains chemicals called usnic acid, evernic acid, and thujone. These chemicals might have various toxic effects in the body.

People use oak moss for cough and other conditions, but there is no good scientific evidence to support these uses.

Don’t confuse oak moss with other types of lichens such as usnea. These are not the same.



Uses & Effectiveness

We currently have no information for Oak Moss overview.

Side Effects

When taken by mouth: Oak moss is possibly safe when used short-term as a water-based tea. But oak moss is likely unsafe when taken in large amounts, for long periods of time, or as an alcohol extract. Oak moss contains toxic chemicals that can cause side effects such as vomiting, dizziness, tremors, kidney damage, and liver damage.

When applied to the skin: There isn't enough reliable information to know if oak moss is safe. It might cause allergic reactions, including skin rash, in some people.

Special Precautions and Warnings

When taken by mouth: Oak moss is possibly safe when used short-term as a water-based tea. But oak moss is likely unsafe when taken in large amounts, for long periods of time, or as an alcohol extract. Oak moss contains toxic chemicals that can cause side effects such as vomiting, dizziness, tremors, kidney damage, and liver damage.

When applied to the skin: There isn't enough reliable information to know if oak moss is safe. It might cause allergic reactions, including skin rash, in some people.

Pregnancy and breast-feeding: Oak moss is possibly unsafe to use while pregnant or breast-feeding. It contains a chemical called thujone that might cause the uterus to contract, and this could cause a miscarriage.

Allergy to lichens and mosses: If you are allergic to lichens and mosses, you might also be allergic to oak moss.

A blood disorder called porphyria: Oak moss might make this condition worse. Don't use oak moss if you have porphyria.

Kidney problems: Oak moss contains chemicals that might harm the kidneys. Don't use oak moss if you have kidney problems.

Liver disease: Oak moss contains chemicals that might harm the liver. If you have liver disease, don't take oak moss by mouth.

Interactions

We currently have no information for Oak Moss overview.

Dosing

There isn’t enough reliable information to know what an appropriate dose of oak moss 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.
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CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

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