Sacred to the Druids, the oak tree has been esteemed in European herbal medicine for its astringent bark, leaves and acorns. Swollen tonsils and sore throats are commonly treated with a solution of popular oak bark. To treat problems including anal fissures, tiny burns, and other skin issues, it can also be administered as a cleanser, cream, or balm. Less frequently, a solution of the bark is used to treat rectal bleeds, nausea, and dysentery. Oak bark powder can be applied over eczema to cure the infected area or inhaled to cure nasal polyps.