Oak

All parts of the oak, especially unripe acorns, are poisonous due to the tannins they contain and can lead to gastrointestinal symptoms (irritation of the stomach lining, vomiting, diarrhea). Oak is used as a medicinal plant due to its tannins. Fresh oak bark is collected in spring. Dried and ground, a decoction is made from it, which is used both externally and as a tea (never more than two cups a day). Oak bark extracts are used externally as a bath or poultice (see Quercus cortex below). Oak bark extracts contain tannin, tannic acid, tannins (see also tannin), bitter substances, gallic acid, quercin, quercetin. They have astringent, antibacterial, hemostatic and anti-inflammatory effects. Indications: eczema, chronic wounds, blepharitis, hyperhidrosis, tinea pedis, intertrigo. The oak flower is used as the Bach flower Oak (see Bach flower therapy below).

• From an allergological point of view, oak pollen only plays a minor role (see pollen, tree pollen below).
• Of clinical relevance is the infestation of oak trees by the oak processionary moth. The oak processionary moth, which is increasingly found in Central Europe, settles exclusively on oak trees. The larvae, also known as butterfly caterpillars, of the oak processionary moth carry poisonous hairs that cause toxic and/or allergic reactions on the skin and mucous membranes. The symptoms range from extremely itchy skin rashes(caterpillar dermatitis) to asthma attacks. As the microscopically small poisonous hairs can be carried up to a hundred meters by the wind, they represent an important cause of " airborne contact dermatitis" that has received little attention to date.