Tannins are chemical compounds that differ from each other structure. Soluble in water found in the leaves of a walnut and tea, oak bark (tannin). They are used as complementary medicines in eczema, burns, herpes, chronic bleeding and injuries, creating a mucosal gelatinous clot and although limiting life activities of cells, it also protects the cells located in the following layers from infections. In a sports used in the treatment of open wounds and edemas (anti-edematous and anti-inflammatory). Oak bark tan- tannin, should be used as directed. Taking larger doses can cause damage to the capillary and the formation of necrotic foci in the liver.