Oak bark (Cortex quercus) supports:

Normal upper respiratory tract function.
Normal skin condition.

Active substance:

Tannins, trace elements and vitamins, phytoncides, flavonoids, and resin.

Allergens:

Does not contain any allergens. But herbs themselves can be allergens. If you are hypersensitive or even allergic to any herb or part of it, do not use it.

Allergens according to European Union Regulation 1169/2011EU, Article 44, Paragraph 1 a) on the provision of information on food

The product does not contain allergenic substances, and no products containing the following allergens were used during its production: gluten, crustaceans, eggs, fish, peanuts, soy, milk, nuts, celery, mustard, sesame, sulfur dioxide and sulfites, lupine and molluscs

Healing effects:

On the basis of Regulation No. 1924/2006 of the European Parliament and the Council of the European Community (and especially with regard to the ambiguities in its interpretation), we as sellers cannot make any nutrition and health claims not approved by the Council for this product. Unfortunately, the list of claims approved by the Council in relation to herbs is not yet complete (and probably won't be for a long time), so we cannot tell you anything about this item here and can only refer you to freely available sources from the Internet Wikipedia.org - Oak bark